Commit Graph

927 Commits

Author SHA1 Message Date
Peter Zijlstra
9a7e0b180d sched: rt-bandwidth fixes
The last patch allows sysctl_sched_rt_runtime to disable bandwidth accounting
for the group scheduler - however it doesn't deal with sched_setscheduler(),
which will keep tasks out of groups that have no assigned runtime.

If we relax this, we get into the situation where RT tasks can get into a group
when we disable bandwidth control, and then starve them by enabling it again.

Rework the schedulability code to check for this condition and fail to turn
on bandwidth control with -EBUSY when this situation is found.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-19 13:10:12 +02:00
Peter Zijlstra
eb755805f2 sched: extract walk_tg_tree()
Extract walk_tg_tree() and make it a little more generic so we can use it
in the schedulablity test.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-19 13:10:11 +02:00
Peter Zijlstra
0b148fa048 sched: rt-bandwidth group disable fixes
More extensive disable of bandwidth control. It allows sysctl_sched_rt_runtime
to disable full group bandwidth control.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-19 13:10:10 +02:00
Linus Torvalds
c100548d46 Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: scale sysctl_sched_shares_ratelimit with nr_cpus
  sched: fix rt-bandwidth hotplug race
  sched: fix the race between walk_tg_tree and sched_create_group
2008-08-16 17:15:32 -07:00
Peter Zijlstra
55cd53404c sched: scale sysctl_sched_shares_ratelimit with nr_cpus
David reported that his Niagra spend a little too much time in
tg_shares_up(), which considering he has a large cpu count makes sense.

So scale the ratelimit value with the number of cpus like we do for
other controls as well.

Reported-by: David Miller <davem@davemloft.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-15 18:25:07 +02:00
Dave Chinner
be4de35263 completions: uninline try_wait_for_completion and completion_done
m68k fails to build with these functions inlined in completion.h.  Move
them out of line into sched.c and export them to avoid this problem.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-15 08:35:44 -07:00
Zhang, Yanmin
09f2724a78 sched: fix the race between walk_tg_tree and sched_create_group
With 2.6.27-rc3, I hit a kernel panic when running volanoMark on my
new x86_64 machine. I also hit it with other 2.6.27-rc kernels.
See below log.

Basically, function walk_tg_tree and sched_create_group have a race
between accessing and initiating tg->children. Below patch fixes it
by moving tg->children initiation to the front of linking tg->siblings
to parent->children.

{----------------panic log------------}

BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
IP: [<ffffffff802292ab>] walk_tg_tree+0x45/0x7f
PGD 1be1c4067 PUD 1bdd8d067 PMD 0
Oops: 0000 [1] SMP
CPU 11
Modules linked in: igb
Pid: 22979, comm: java Not tainted 2.6.27-rc3 #1
RIP: 0010:[<ffffffff802292ab>]  [<ffffffff802292ab>] walk_tg_tree+0x45/0x7f
RSP: 0018:ffff8801bfbbbd18  EFLAGS: 00010083
RAX: 0000000000000000 RBX: ffff8800be0dce40 RCX: ffffffffffffffc0
RDX: ffff880102c43740 RSI: 0000000000000000 RDI: ffff8800be0dce40
RBP: ffff8801bfbbbd48 R08: ffff8800ba437bc8 R09: 0000000000001f40
R10: ffff8801be812100 R11: ffffffff805fdf44 R12: ffff880102c43740
R13: 0000000000000000 R14: ffffffff8022cf0f R15: ffffffff8022749f
FS:  00000000568ac950(0063) GS:ffff8801bfa26d00(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000000 CR3: 00000001bd848000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process java (pid: 22979, threadinfo ffff8801b145a000, task ffff8801bf18e450)
Stack:  0000000000000001 ffff8800ba5c8d60 0000000000000001 0000000000000001
 ffff8800bad1ccb8 0000000000000000 ffff8801bfbbbd98 ffffffff8022ed37
 0000000000000001 0000000000000286 ffff8801bd5ee180 ffff8800ba437bc8
Call Trace:
 <IRQ>  [<ffffffff8022ed37>] try_to_wake_up+0x71/0x24c
 [<ffffffff80247177>] autoremove_wake_function+0x9/0x2e
 [<ffffffff80228039>] ? __wake_up_common+0x46/0x76
 [<ffffffff802296d5>] __wake_up+0x38/0x4f
 [<ffffffff806169cc>] tcp_v4_rcv+0x380/0x62e

Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-14 10:58:48 +02:00
Linus Torvalds
1ea2950884 Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched, cpu hotplug: fix set_cpus_allowed() use in hotplug callbacks
  sched: fix mysql+oltp regression
  sched_clock: delay using sched_clock()
  sched clock: couple local and remote clocks
  sched clock: simplify __update_sched_clock()
  sched: eliminate scd->prev_raw
  sched clock: clean up sched_clock_cpu()
  sched clock: revert various sched_clock() changes
  sched: move sched_clock before first use
  sched: test runtime rather than period in global_rt_runtime()
  sched: fix SCHED_HRTICK dependency
  sched: fix warning in hrtick_start_fair()
2008-08-11 16:46:31 -07:00
Ingo Molnar
23a0ee908c Merge branch 'core/locking' into core/urgent 2008-08-12 00:11:49 +02:00
Ingo Molnar
251a169c69 Merge branch 'linus' into sched/urgent 2008-08-11 13:40:56 +02:00
Peter Zijlstra
1b12bbc747 lockdep: re-annotate scheduler runqueues
Instead of using a per-rq lock class, use the regular nesting operations.

However, take extra care with double_lock_balance() as it can release the
already held rq->lock (and therefore change its nesting class).

So what can happen is:

 spin_lock(rq->lock);	// this rq subclass 0

 double_lock_balance(rq, other_rq);
   // release rq
   // acquire other_rq->lock subclass 0
   // acquire rq->lock subclass 1

 spin_unlock(other_rq->lock);

leaving you with rq->lock in subclass 1

So a subsequent double_lock_balance() call can try to nest a subclass 1
lock while already holding a subclass 1 lock.

Fix this by introducing double_unlock_balance() which releases the other
rq's lock, but also re-sets the subclass for this rq's lock to 0.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-11 09:30:22 +02:00
Jeremy Fitzhardinge
725aad24c3 __sched_setscheduler: don't do any policy checks when not "user"
The "user" parameter to __sched_setscheduler indicates whether the
change is being done on behalf of a user process or not.  If not, we
shouldn't apply any permissions checks, so don't call
security_task_setscheduler().

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-04 17:16:20 -07:00
Peter Zijlstra
5e710e37bd lockdep: change scheduler annotation
While thinking about David's graph walk lockdep patch it _finally_
dawned on me that there is no reason we have a lock class per cpu ...

Sorry for being dense :-/

The below changes the annotation from a lock class per cpu, to a single
nested lock, as the scheduler never holds more that 2 rq locks at a time
anyway.

If there was code requiring holding all rq locks this would not work and
the original annotation would be the only option, but that not being the
case, this is a much lighter one.

Compiles and boots on a 2-way x86_64.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-01 10:46:48 +02:00
Andi Kleen
f718cd4add sched: make scheduler sysfs attributes sysdev class devices
They are really class devices, but were incorrectly declared.  This
leads to crashes with the recent changes that makes non normal sysdevs
use a different prototype.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pierre Ossman <drzeus-list@drzeus.cx>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-30 09:41:47 -07:00
roel kluin
e26873bb10 sched: test runtime rather than period in global_rt_runtime()
Test runtime rather than period

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-28 15:57:24 +02:00
Roland McGrath
85ba2d862e tracehook: wait_task_inactive
This extends wait_task_inactive() with a new argument so it can be used in
a "soft" mode where it will check for the task changing state unexpectedly
and back off.  There is no change to existing callers.  This lays the
groundwork to allow robust, noninvasive tracing that can try to sample a
blocked thread but back off safely if it wakes up.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26 12:00:09 -07:00
Eduard - Gabriel Munteanu
7babe8db99 Full conversion to early_initcall() interface, remove old interface
A previous patch added the early_initcall(), to allow a cleaner hooking of
pre-SMP initcalls.  Now we remove the older interface, converting all
existing users to the new one.

[akpm@linux-foundation.org: cleanups]
[akpm@linux-foundation.org: build fix]
[kosaki.motohiro@jp.fujitsu.com: warning fix]
[kosaki.motohiro@jp.fujitsu.com: warning fix]
Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26 12:00:04 -07:00
Jonathan Lim
49b5cf3472 accounting: account for user time when updating memory integrals
Adapt acct_update_integrals() to include user time when calculating the time
difference.  The units of acct_rss_mem1 and acct_vm_mem1 are also changed from
pages-jiffies to pages-usecs to avoid calling jiffies_to_usecs() in
xacct_add_tsk() which might overflow.

Signed-off-by: Jonathan Lim <jlim@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 10:53:46 -07:00
Linus Torvalds
7f9dce3837 Merge branch 'sched/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: hrtick_enabled() should use cpu_active()
  sched, x86: clean up hrtick implementation
  sched: fix build error, provide partition_sched_domains() unconditionally
  sched: fix warning in inc_rt_tasks() to not declare variable 'rq' if it's not needed
  cpu hotplug: Make cpu_active_map synchronization dependency clear
  cpu hotplug, sched: Introduce cpu_active_map and redo sched domain managment (take 2)
  sched: rework of "prioritize non-migratable tasks over migratable ones"
  sched: reduce stack size in isolated_cpu_setup()
  Revert parts of "ftrace: do not trace scheduler functions"

Fixed up conflicts in include/asm-x86/thread_info.h (due to the
TIF_SINGLESTEP unification vs TIF_HRTICK_RESCHED removal) and
kernel/sched_fair.c (due to cpu_active_map vs for_each_cpu_mask_nr()
introduction).
2008-07-23 19:36:53 -07:00
Linus Torvalds
26dcce0fab Merge branch 'cpus4096-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'cpus4096-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (31 commits)
  NR_CPUS: Replace NR_CPUS in speedstep-centrino.c
  cpumask: Provide a generic set of CPUMASK_ALLOC macros, FIXUP
  NR_CPUS: Replace NR_CPUS in cpufreq userspace routines
  NR_CPUS: Replace per_cpu(..., smp_processor_id()) with __get_cpu_var
  NR_CPUS: Replace NR_CPUS in arch/x86/kernel/genapic_flat_64.c
  NR_CPUS: Replace NR_CPUS in arch/x86/kernel/genx2apic_uv_x.c
  NR_CPUS: Replace NR_CPUS in arch/x86/kernel/cpu/proc.c
  NR_CPUS: Replace NR_CPUS in arch/x86/kernel/cpu/mcheck/mce_64.c
  cpumask: Optimize cpumask_of_cpu in lib/smp_processor_id.c, fix
  cpumask: Use optimized CPUMASK_ALLOC macros in the centrino_target
  cpumask: Provide a generic set of CPUMASK_ALLOC macros
  cpumask: Optimize cpumask_of_cpu in lib/smp_processor_id.c
  cpumask: Optimize cpumask_of_cpu in kernel/time/tick-common.c
  cpumask: Optimize cpumask_of_cpu in drivers/misc/sgi-xp/xpc_main.c
  cpumask: Optimize cpumask_of_cpu in arch/x86/kernel/ldt.c
  cpumask: Optimize cpumask_of_cpu in arch/x86/kernel/io_apic_64.c
  cpumask: Replace cpumask_of_cpu with cpumask_of_cpu_ptr
  Revert "cpumask: introduce new APIs"
  cpumask: make for_each_cpu_mask a bit smaller
  net: Pass reference to cpumask variable in net/sunrpc/svc.c
  ...

Fix up trivial conflicts in drivers/cpufreq/cpufreq.c manually
2008-07-23 18:37:44 -07:00
Andi Kleen
4a0b2b4dbe sysdev: Pass the attribute to the low level sysdev show/store function
This allow to dynamically generate attributes and share show/store
functions between attributes. Right now most attributes are generated
by special macros and lots of duplicated code. With the attribute
passed it's instead possible to attach some data to the attribute
and then use that in shared low level functions to do different things.

I need this for the dynamically generated bank attributes in the x86
machine check code, but it'll allow some further cleanups.

I converted all users in tree to the new show/store prototype. It's a single
huge patch to avoid unbisectable sections.

Runtime tested: x86-32, x86-64
Compiled only: ia64, powerpc
Not compile tested/only grep converted: sh, arm, avr32

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-07-21 21:55:02 -07:00
Ingo Molnar
ba42059fbd sched: hrtick_enabled() should use cpu_active()
Peter pointed out that hrtick_enabled() should use cpu_active().

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-20 11:02:06 +02:00
Ingo Molnar
d986434a7d Merge branch 'sched/urgent' into sched/devel 2008-07-20 11:01:29 +02:00
Peter Zijlstra
31656519e1 sched, x86: clean up hrtick implementation
random uvesafb failures were reported against Gentoo:

  http://bugs.gentoo.org/show_bug.cgi?id=222799

and Mihai Moldovan bisected it back to:

> 8f4d37ec07 is first bad commit
> commit 8f4d37ec07
> Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Date:   Fri Jan 25 21:08:29 2008 +0100
>
>    sched: high-res preemption tick

Linus suspected it to be hrtick + vm86 interaction and observed:

> Btw, Peter, Ingo: I think that commit is doing bad things. They aren't
> _incorrect_ per se, but they are definitely bad.
>
> Why?
>
> Using random _TIF_WORK_MASK flags is really impolite for doing
> "scheduling" work. There's a reason that arch/x86/kernel/entry_32.S
> special-cases the _TIF_NEED_RESCHED flag: we don't want to exit out of
> vm86 mode unnecessarily.
>
> See the "work_notifysig_v86" label, and how it does that
> "save_v86_state()" thing etc etc.

Right, I never liked having to fiddle with those TIF flags. Initially I
needed it because the hrtimer base lock could not nest in the rq lock.
That however is fixed these days.

Currently the only reason left to fiddle with the TIF flags is remote
wakeups. We cannot program a remote cpu's hrtimer. I've been thinking
about using the new and improved IPI function call stuff to implement
hrtimer_start_on().

However that does require that smp_call_function_single(.wait=0) works
from interrupt context - /me looks at the latest series from Jens - Yes
that does seem to be supported, good.

Here's a stab at cleaning this stuff up ...

Mihai reported test success as well.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Mihai Moldovan <ionic@ionic.de>
Cc: Michal Januszewski <spock@gentoo.org>
Cc: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-20 10:37:28 +02:00
Max Krasnyansky
e761b77252 cpu hotplug, sched: Introduce cpu_active_map and redo sched domain managment (take 2)
This is based on Linus' idea of creating cpu_active_map that prevents
scheduler load balancer from migrating tasks to the cpu that is going
down.

It allows us to simplify domain management code and avoid unecessary
domain rebuilds during cpu hotplug event handling.

Please ignore the cpusets part for now. It needs some more work in order
to avoid crazy lock nesting. Although I did simplfy and unify domain
reinitialization logic. We now simply call partition_sched_domains() in
all the cases. This means that we're using exact same code paths as in
cpusets case and hence the test below cover cpusets too.
Cpuset changes to make rebuild_sched_domains() callable from various
contexts are in the separate patch (right next after this one).

This not only boots but also easily handles
	while true; do make clean; make -j 8; done
and
	while true; do on-off-cpu 1; done
at the same time.
(on-off-cpu 1 simple does echo 0/1 > /sys/.../cpu1/online thing).

Suprisingly the box (dual-core Core2) is quite usable. In fact I'm typing
this on right now in gnome-terminal and things are moving just fine.

Also this is running with most of the debug features enabled (lockdep,
mutex, etc) no BUG_ONs or lockdep complaints so far.

I believe I addressed all of the Dmitry's comments for original Linus'
version. I changed both fair and rt balancer to mask out non-active cpus.
And replaced cpu_is_offline() with !cpu_active() in the main scheduler
code where it made sense (to me).

Signed-off-by: Max Krasnyanskiy <maxk@qualcomm.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Gregory Haskins <ghaskins@novell.com>
Cc: dmitry.adamushko@gmail.com
Cc: pj@sgi.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 13:22:25 +02:00
Mike Travis
13b40c1e40 sched: reduce stack size in isolated_cpu_setup()
* Remove 16k stack requirements in isolated_cpu_setup when NR_CPUS=4096.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 11:55:42 +02:00
Ingo Molnar
82638844d9 Merge branch 'linus' into cpus4096
Conflicts:

	arch/x86/xen/smp.c
	kernel/sched_rt.c
	net/iucv/iucv.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-16 00:29:07 +02:00
Linus Torvalds
666484f025 Merge branch 'core/softirq' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core/softirq' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  softirq: remove irqs_disabled warning from local_bh_enable
  softirq: remove initialization of static per-cpu variable
  Remove argument from open_softirq which is always NULL
2008-07-14 15:28:42 -07:00
Linus Torvalds
948769a5ba Merge branch 'sched/new-API-sched_setscheduler' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched/new-API-sched_setscheduler' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: add new API sched_setscheduler_nocheck: add a flag to control access checks
2008-07-14 14:50:49 -07:00
Ingo Molnar
5806b81ac1 Merge branch 'auto-ftrace-next' into tracing/for-linus
Conflicts:

	arch/x86/kernel/entry_32.S
	arch/x86/kernel/process_32.c
	arch/x86/kernel/process_64.c
	arch/x86/lib/Makefile
	include/asm-x86/irqflags.h
	kernel/Makefile
	kernel/sched.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-14 16:11:52 +02:00
Ingo Molnar
d14c8a680c Merge branch 'sched/for-linus' into tracing/for-linus 2008-07-14 16:11:02 +02:00
Ingo Molnar
54ef76f37b Merge branch 'linus' into sched/devel 2008-07-13 08:50:13 +02:00
Ingo Molnar
ae94b8075a Merge branch 'linus' into x86/core
Conflicts:

	arch/x86/mm/ioremap.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-12 07:29:02 +02:00
Linus Torvalds
b1e387348a sched: fix cpu hotplug, cleanup
Clean up __migrate_task(): to just have separate "done" and "fail"
cases, instead of that "out" case with random error behavior.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-10 20:39:58 +02:00
Ingo Molnar
bac0c9103b Merge branch 'tracing/ftrace' into auto-ftrace-next 2008-07-10 11:43:00 +02:00
Dmitry Adamushko
dc7fab8b3b sched: fix cpu hotplug
I think we may have a race between try_to_wake_up() and
migrate_live_tasks() -> move_task_off_dead_cpu() when the later one
may end up looping endlessly.

Interrupts are enabled on other CPUs when migration_call(CPU_DEAD, ...) is
called so we may get a race between try_to_wake_up() and
migrate_live_tasks() -> move_task_off_dead_cpu(). The former one may push
a task out of a dead CPU causing the later one to loop endlessly.

Heiko Carstens observed:

| That's exactly what explains a dump I got yesterday. Thanks for fixing! :)

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Cc: miaox@cn.fujitsu.com
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Avi Kivity <avi@qumranet.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-10 09:35:34 +02:00
Mike Travis
076ac2af86 sched, numa: replace MAX_NUMNODES with nr_node_ids in kernel/sched.c
* Replace usages of MAX_NUMNODES with nr_node_ids in kernel/sched.c,
    where appropriate.  This saves some allocated space as well as many
    wasted cycles going through node entries that are non-existent.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-08 11:31:30 +02:00
Ingo Molnar
032f82786f Merge commit 'v2.6.26-rc9' into sched/devel 2008-07-07 08:01:26 +02:00
Ingo Molnar
68083e05d7 Merge commit 'v2.6.26-rc9' into cpus4096 2008-07-06 14:23:39 +02:00
Ankita Garg
46ac22bab4 sched: fix accounting in task delay accounting & migration
On Thu, Jun 19, 2008 at 12:27:14PM +0200, Peter Zijlstra wrote:
> On Thu, 2008-06-05 at 10:50 +0530, Ankita Garg wrote:
>
> > Thanks Peter for the explanation...
> >
> > I agree with the above and that is the reason why I did not see weird
> > values with cpu_time. But, run_delay still would suffer skews as the end
> > points for delta could be taken on different cpus due to migration (more
> > so on RT kernel due to the push-pull operations). With the below patch,
> > I could not reproduce the issue I had seen earlier. After every dequeue,
> > we take the delta and start wait measurements from zero when moved to a
> > different rq.
>
> OK, so task delay delay accounting is broken because it doesn't take
> migration into account.
>
> What you've done is make it symmetric wrt enqueue, and account it like
>
>   cpu0      cpu1
>
> enqueue
>  <wait-d1>
> dequeue
>             enqueue
>              <wait-d2>
>             run
>
> Where you add both d1 and d2 to the run_delay,.. right?
>

Thanks for reviewing the patch. The above is exactly what I have done.

> This seems like a good fix, however it looks like the patch will break
> compilation in !CONFIG_SCHEDSTATS && !CONFIG_TASK_DELAY_ACCT, of it
> failing to provide a stub for sched_info_dequeue() in that case.

Fixed. Pl. find the new patch below.

Signed-off-by: Ankita Garg <ankita@in.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Gregory Haskins <ghaskins@novell.com>
Cc: rostedt@goodmis.org
Cc: suresh.b.siddha@intel.com
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dhaval@linux.vnet.ibm.com
Cc: vatsa@linux.vnet.ibm.com
Cc: David Bahi <DBahi@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-04 12:50:23 +02:00
Gregory Haskins
2087a1ad82 sched: add avg-overlap support to RT tasks
We have the notion of tracking process-coupling (a.k.a. buddy-wake) via
the p->se.last_wake / p->se.avg_overlap facilities, but it is only used
for cfs to cfs interactions.  There is no reason why an rt to cfs
interaction cannot share in establishing a relationhip in a similar
manner.

Because PREEMPT_RT runs many kernel threads as FIFO priority, we often
times have heavy interaction between RT threads waking CFS applications.
This patch offers a substantial boost (50-60%+) in perfomance under those
circumstances.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Cc: npiggin@suse.de
Cc: rostedt@goodmis.org
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-04 12:50:22 +02:00
Gregory Haskins
c4acb2c066 sched: terminate newidle balancing once at least one task has moved over
Inspired by Peter Zijlstra.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Cc: npiggin@suse.de
Cc: rostedt@goodmis.org
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-04 12:50:21 +02:00
Raistlin
619b048803 sched: fix divide error when trying to configure rt_period to zero
Here it is another little Oops we found while configuring invalid values
via cgroups:

echo 0 > /dev/cgroups/0/cpu.rt_period_us
or
echo 4294967296 > /dev/cgroups/0/cpu.rt_period_us

[  205.509825] divide error: 0000 [#1]
[  205.510151] Modules linked in:
[  205.510151]
[  205.510151] Pid: 2339, comm: bash Not tainted (2.6.26-rc8 #33)
[  205.510151] EIP: 0060:[<c030c6ef>] EFLAGS: 00000293 CPU: 0
[  205.510151] EIP is at div64_u64+0x5f/0x70
[  205.510151] EAX: 0000389f EBX: 00000000 ECX: 00000000 EDX: 00000000
[  205.510151] ESI: d9800000 EDI: 00000000 EBP: c6cede60 ESP: c6cede50
[  205.510151]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
[  205.510151] Process bash (pid: 2339, ti=c6cec000 task=c79be370 task.ti=c6cec000)
[  205.510151] Stack: d9800000 0000389f c05971a0 d9800000 c6cedeb4 c0214dbd 00000000 00000000
[  205.510151]        c6cede88 c0242bd8 c05377c0 c7a41b40 00000000 00000000 00000000 c05971a0
[  205.510151]        c780ed20 c7508494 c7a41b40 00000000 00000002 c6cedebc c05971a0 ffffffea
[  205.510151] Call Trace:
[  205.510151]  [<c0214dbd>] ? __rt_schedulable+0x1cd/0x240
[  205.510151]  [<c0242bd8>] ? cgroup_file_open+0x18/0xe0
[  205.510151]  [<c0214fe4>] ? tg_set_bandwidth+0xa4/0xf0
[  205.510151]  [<c0215066>] ? sched_group_set_rt_period+0x36/0x50
[  205.510151]  [<c021508e>] ? cpu_rt_period_write_uint+0xe/0x10
[  205.510151]  [<c0242dc5>] ? cgroup_file_write+0x125/0x160
[  205.510151]  [<c0232c15>] ? hrtimer_interrupt+0x155/0x190
[  205.510151]  [<c02f047f>] ? security_file_permission+0xf/0x20
[  205.510151]  [<c0277ad8>] ? rw_verify_area+0x48/0xc0
[  205.510151]  [<c0283744>] ? dupfd+0x104/0x130
[  205.510151]  [<c027838c>] ? vfs_write+0x9c/0x160
[  205.510151]  [<c0242ca0>] ? cgroup_file_write+0x0/0x160
[  205.510151]  [<c027850d>] ? sys_write+0x3d/0x70
[  205.510151]  [<c0203019>] ? sysenter_past_esp+0x6a/0x91
[  205.510151]  =======================
[  205.510151] Code: 0f 45 de 31 f6 0f ad d0 d3 ea f6 c1 20 0f 45 c2 0f 45 d6 89 45 f0 89 55 f4 8b 55 f4 31 c9 8b 45 f0 39 d3 89 c6 77 08 89 d0 31 d2 <f7> f3 89 c1 83 c4 08 89 f0 f7 f3 89 ca 5b 5e 5d c3 55 89 e5 56
[  205.510151] EIP: [<c030c6ef>] div64_u64+0x5f/0x70 SS:ESP 0068:c6cede50

The attached patch solves the issue for me.

I'm checking as soon as possible for the period not being zero since, if
it is, going ahead is useless. This way we also save a mutex_lock() and
a read_lock() wrt doing it inside tg_set_bandwidth() or
__rt_schedulable().

Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-01 08:23:24 +02:00
Vegard Nossum
30432094a7 sched: fix warning
This patch fixes the following warning:

kernel/sched.c:1667: warning: 'cfs_rq_set_shares' defined but not used

This seems the correct way to fix this; cfs_rq_set_shares() is only used
in a single place, which is also inside #ifdef CONFIG_FAIR_GROUP_SCHED.

Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-30 08:37:32 +02:00
Ingo Molnar
34e83e850f sched: build fix
fix:

kernel/sched.c: In function ‘sched_group_set_shares':
kernel/sched.c:8635: error: implicit declaration of function ‘cfs_rq_set_shares'

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-30 08:37:13 +02:00
Dmitry Adamushko
79c537998d sched: fix cpu hotplug
the CPU hotplug problems (crashes under high-volume unplug+replug
tests) seem to be related to migrate_dead_tasks().

Firstly I added traces to see all tasks being migrated with
migrate_live_tasks() and migrate_dead_tasks(). On my setup the problem
pops up (the one with "se == NULL" in the loop of
pick_next_task_fair()) shortly after the traces indicate that some has
been migrated with migrate_dead_tasks()). btw., I can reproduce it
much faster now with just a plain cpu down/up loop.

[disclaimer] Well, unless I'm really missing something important in
this late hour [/desclaimer] pick_next_task() is not something
appropriate for migrate_dead_tasks() :-)

the following change seems to eliminate the problem on my setup
(although, I kept it running only for a few minutes to get a few
messages indicating migrate_dead_tasks() does move tasks and the
system is still ok)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-29 08:50:21 +02:00
Peter Zijlstra
f1d239f732 sched: incremental effective_load()
Increase the accuracy of the effective_load values.

Not only consider the current increment (as per the attempted wakeup), but
also consider the delta between when we last adjusted the shares and the
current situation.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:47 +02:00
Peter Zijlstra
83378269a5 sched: correct wakeup weight calculations
rw_i = {2, 4, 1, 0}
s_i = {2/7, 4/7, 1/7, 0}

wakeup on cpu0, weight=1

rw'_i = {3, 4, 1, 0}
s'_i = {3/8, 4/8, 1/8, 0}

s_0 = S * rw_0 / \Sum rw_j ->
  \Sum rw_j = S*rw_0/s_0 = 1*2*7/2 = 7 (correct)

s'_0 = S * (rw_0 + 1) / (\Sum rw_j + 1) =
       1 * (2+1) / (7+1) = 3/8 (correct

so we find that adding 1 to cpu0 gains 5/56 in weight
if say the other cpu were, cpu1, we'd also have to calculate its 4/56 loss

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:46 +02:00
Peter Zijlstra
2398f2c6d3 sched: update shares on wakeup
We found that the affine wakeup code needs rather accurate load figures
to be effective. The trouble is that updating the load figures is fairly
expensive with group scheduling. Therefore ratelimit the updating.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:45 +02:00
Peter Zijlstra
cd80917e4f sched: fix shares boost logic
In case the domain is empty, pretend there is a single task on each cpu, so
that together with the boost logic we end up giving 1/n shares to each
cpu.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:44 +02:00
Peter Zijlstra
93b75217df sched: disable source/target_load bias
The bias given by source/target_load functions can be very large, disable
it by default to get faster convergence.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:44 +02:00
Peter Zijlstra
051c67640e sched: remove prio preference from balance decisions
Priority looses much of its meaning in a hierarchical context. So don't
use it in balance decisions.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:42 +02:00
Peter Zijlstra
408ed066b1 sched: hierarchical load vs find_busiest_group
find_busiest_group() has some assumptions about task weight being in the
NICE_0_LOAD range. Hierarchical task groups break this assumption - fix this
by replacing it with the average task weight, which will adapt the situation.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:40 +02:00
Peter Zijlstra
a8a51d5e59 sched: persistent average load per task
Remove the fall-back to SCHED_LOAD_SCALE by remembering the previous value of
cpu_avg_load_per_task() - this is useful because of the hierarchical group
model in which task weight can be much smaller.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:39 +02:00
Peter Zijlstra
039a1c41b3 sched: fix sched_balance_self() smp group balancing
Finding the least idle cpu is more accurate when done with updated shares.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:38 +02:00
Peter Zijlstra
3e5459b4be sched: fix newidle smp group balancing
Re-compute the shares on newidle - so we can make a decision based on
recent data.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:37 +02:00
Peter Zijlstra
c8cba857b4 sched: simplify the group load balancer
While thinking about the previous patch - I realized that using per domain
aggregate load values in load_balance_fair() is wrong. We should use the
load value for that CPU.

By not needing per domain hierarchical load values we don't need to store
per domain aggregate shares, which greatly simplifies all the math.

It basically falls apart in two separate computations:
 - per domain update of the shares
 - per CPU update of the hierarchical load

Also get rid of the move_group_shares() stuff - just re-compute the shares
again after a successful load balance.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:36 +02:00
Peter Zijlstra
a25b5aca87 sched: no need to aggregate task_weight
We only need to know the task_weight of the busiest rq - nothing to do
if there are no tasks there.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:35 +02:00
Peter Zijlstra
d3f40dbab9 sched: dont micro manage share losses
We used to try and contain the loss of 'shares' by playing arithmetic
games. Replace that by noticing that at the top sched_domain we'll
always have the full weight in shares to distribute.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:34 +02:00
Peter Zijlstra
4d8d595dfa sched: update aggregate when holding the RQs
It was observed that in __update_group_shares_cpu()

  rq_weight > aggregate()->rq_weight

This is caused by forks/wakeups in between the initial aggregate pass and
locking of the RQs for load balance. To avoid this situation partially re-do
the aggregation once we have the RQs locked (which avoids new tasks from
appearing).

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:33 +02:00
Peter Zijlstra
b6a86c746f sched: fix sched_domain aggregation
Keeping the aggregate on the first cpu of the sched domain has two problems:
 - it could collide between different sched domains on different cpus
 - it could slow things down because of the remote accesses

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:32 +02:00
Peter Zijlstra
103638d95b sched: fix wakeup granularity and buddy granularity
Uncouple buddy selection from wakeup granularity.

The initial idea was that buddies could run ahead as far as a normal task
can - do this by measuring a pair 'slice' just as we do for a normal task.

This means we can drop the wakeup_granularity back to 5ms.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:31 +02:00
Peter Zijlstra
76a2a6ee8a sched: sched_clock_cpu() based cpu_clock()
with sched_clock_cpu() being reasonably in sync between cpus (max 1 jiffy
difference) use this to provide cpu_clock().

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:30 +02:00
Peter Zijlstra
c09595f63b sched: revert revert of: fair-group: SMP-nice for group scheduling
Try again..

Initial commit: 18d95a2832
Revert: 6363ca57c7

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:29 +02:00
Peter Zijlstra
a7be37ac8e sched: revert the revert of: weight calculations
Try again..

initial commit: 8f1bc385cf
revert: f9305d4a09

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-27 14:31:27 +02:00
Ingo Molnar
97e6722b8d Merge branch 'linus' into tracing/ftrace 2008-06-25 12:27:56 +02:00
Ingo Molnar
773dc8eaca Merge branch 'linus' into sched/new-API-sched_setscheduler 2008-06-25 12:27:05 +02:00
Ingo Molnar
f57aec5a87 Merge branch 'linus' into sched/devel
Conflicts:

	kernel/sched_rt.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-25 12:26:59 +02:00
Ingo Molnar
ace7f1b796 Merge branch 'linus' into core/softirq 2008-06-25 12:23:59 +02:00
Rusty Russell
961ccddd59 sched: add new API sched_setscheduler_nocheck: add a flag to control access checks
Hidehiro Kawai noticed that sched_setscheduler() can fail in
stop_machine: it calls sched_setscheduler() from insmod, which can
have CAP_SYS_MODULE without CAP_SYS_NICE.

Two cases could have failed, so are changed to sched_setscheduler_nocheck:
  kernel/softirq.c:cpu_callback()
	- CPU hotplug callback
  kernel/stop_machine.c:__stop_machine_run()
	- Called from various places, including modprobe()

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: sugita <yumiko.sugita.yf@hitachi.com>
Cc: Satoshi OSHIMA <satoshi.oshima.fk@hitachi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-23 22:57:56 +02:00
Ingo Molnar
1de8644cc7 Merge branch 'linus' into sched/devel 2008-06-23 11:30:23 +02:00
Ingo Molnar
f34bfb1bee Merge branch 'linus' into tracing/ftrace 2008-06-23 11:11:42 +02:00
Ingo Molnar
198bb971e2 Merge branch 'linus' into sched/urgent 2008-06-23 11:00:26 +02:00
Ingo Molnar
a60b33cf59 Merge branch 'linus' into core/softirq 2008-06-23 10:52:59 +02:00
Linus Torvalds
1f1e2ce8a5 Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  softlockup: fix NMI hangs due to lock race - 2.6.26-rc regression
  rcupreempt: remove export of rcu_batches_completed_bh
  cpuset: limit the input of cpuset.sched_relax_domain_level
2008-06-20 12:37:13 -07:00
Oleg Nesterov
ea71a54670 sched: refactor wait_for_completion_timeout()
Simplify the code and fix the boundary condition of
wait_for_completion_timeout(,0).

We can kill the first __remove_wait_queue() as well.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2008-06-20 17:15:49 +02:00
Roland Dreier
bb10ed0994 sched: fix wait_for_completion_timeout() spurious failure under heavy load
It seems that the current implementaton of wait_for_completion_timeout()
has a small problem under very high load for the common pattern:

	if (!wait_for_completion_timeout(&done, timeout))
		/* handle failure */

because the implementation very roughly does (lots of code deleted to
show the basic flow):

	static inline long __sched
	do_wait_for_common(struct completion *x, long timeout, int state)
	{
		if (x->done)
			return timeout;

		do {
			timeout = schedule_timeout(timeout);

			if (!timeout)
				return timeout;

		} while (!x->done);

		return timeout;
	}

so if the system is very busy and x->done is not set when
do_wait_for_common() is entered, it is possible that the first call to
schedule_timeout() returns 0 because the task doing wait_for_completion
doesn't get rescheduled for a long time, even if it is woken up early
enough.

In this case, wait_for_completion_timeout() returns 0 without even
checking x->done again, and the code above falls into its failure case
purely for scheduler reasons, even if the hardware event or whatever was
being waited for happened early enough.

It would make sense to add an extra test to do_wait_for() in the timeout
case and return 1 if x->done is actually set.

A quick audit (not exhaustive) of wait_for_completion_timeout() callers
seems to indicate that no one actually cares about the return value in
the success case -- they just test for 0 (timed out) versus non-zero
(wait succeeded).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-20 13:19:32 +02:00
Peter Zijlstra
10b612f440 sched: rt: fix the bandwidth contraint computations
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Daniel K." <dk@uw.no>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-20 10:26:01 +02:00
Li Zefan
30e0e17819 cpuset: limit the input of cpuset.sched_relax_domain_level
We allow the inputs to be [-1 ... SD_LV_MAX), and return -EINVAL
for inputs outside this range.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Acked-by: Paul Jackson <pj@sgi.com>
Acked-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-19 09:45:36 +02:00
Max Krasnyansky
f18f982abf sched: CPU hotplug events must not destroy scheduler domains created by the cpusets
First issue is not related to the cpusets. We're simply leaking doms_cur.
It's allocated in arch_init_sched_domains() which is called for every
hotplug event. So we just keep reallocation doms_cur without freeing it.
I introduced free_sched_domains() function that cleans things up.

Second issue is that sched domains created by the cpusets are
completely destroyed by the CPU hotplug events. For all CPU hotplug
events scheduler attaches all CPUs to the NULL domain and then puts
them all into the single domain thereby destroying domains created
by the cpusets (partition_sched_domains).
The solution is simple, when cpusets are enabled scheduler should not
create default domain and instead let cpusets do that. Which is
exactly what the patch does.

Signed-off-by: Max Krasnyansky <maxk@qualcomm.com>
Cc: pj@sgi.com
Cc: menage@google.com
Cc: rostedt@goodmis.org
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-19 09:14:51 +02:00
Ingo Molnar
1cdad71537 Merge branch 'sched' into sched-devel
Conflicts:

	kernel/sched_rt.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 09:09:15 +02:00
Peter Zijlstra
7ea56616ba sched: rt-group: fix hierarchy
Don't re-set the entity's runqueue to the wrong rq after we've set it
to the right one.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Daniel K. <dk@uw.no>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 09:06:56 +02:00
Dario Faggioli
49307fd6f7 sched: NULL pointer dereference while setting sched_rt_period_us
When CONFIG_RT_GROUP_SCHED and CONFIG_CGROUP_SCHED are enabled, with:

 echo 10000 > /proc/sys/kernel/sched_rt_period_us

We get this:

 BUG: unable to handle kernel NULL pointer dereference at 0000008c
 [  947.682233] IP: [<c0216b72>] __rt_schedulable+0x12/0x160
 [  947.683123] *pde = 00000000=20
 [  947.683782] Oops: 0000 [#1]
 [  947.684307] Modules linked in:
 [  947.684308]
 [  947.684308] Pid: 2359, comm: bash Not tainted (2.6.26-rc6 #8)
 [  947.684308] EIP: 0060:[<c0216b72>] EFLAGS: 00000246 CPU: 0
 [  947.684308] EIP is at __rt_schedulable+0x12/0x160
 [  947.684308] EAX: 00000000 EBX: 00000000 ECX: 00000000 EDX: 00000001
 [  947.684308] ESI: c0521db4 EDI: 00000001 EBP: c6cc9f00 ESP: c6cc9ed0
 [  947.684308]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
 [  947.684308] Process bash (pid: 2359, tiÆcc8000 taskÇa54f00=20 task.tiÆcc8000)
 [  947.684308] Stack: c0222790 00000000 080f8c08 c0521db4 c6cc9f00 00000001 00000000 00000000
 [  947.684308]        c6cc9f9c 00000000 c0521db4 00000001 c6cc9f28 c0216d40 00000000 00000000
 [  947.684308]        c6cc9f9c 000f4240 000e7ef0 ffffffff c0521db4 c79dfb60 c6cc9f58 c02af2cc
 [  947.684308] Call Trace:
 [  947.684308]  [<c0222790>] ? do_proc_dointvec_conv+0x0/0x50
 [  947.684308]  [<c0216d40>] ? sched_rt_handler+0x80/0x110
 [  947.684308]  [<c02af2cc>] ? proc_sys_call_handler+0x9c/0xb0
 [  947.684308]  [<c02af2fa>] ? proc_sys_write+0x1a/0x20
 [  947.684308]  [<c0273c36>] ? vfs_write+0x96/0x160
 [  947.684308]  [<c02af2e0>] ? proc_sys_write+0x0/0x20
 [  947.684308]  [<c027423d>] ? sys_write+0x3d/0x70
 [  947.684308]  [<c0202ef5>] ? sysenter_past_esp+0x6a/0x91
 [  947.684308]  =======================
 [  947.684308] Code: 24 04 e8 62 b1 0e 00 89 c7 89 f8 8b 5d f4 8b 75
 f8 8b 7d fc 89 ec 5d c3 90 55 89 e5 57 56 53 83 ec 24 89 45 ec 89 55 e4
 89 4d e8 <8b> b8 8c 00 00 00 85 ff 0f 84 c9 00 00 00 8b 57 24 39 55 e8
 8b
 [  947.684308] EIP: [<c0216b72>] __rt_schedulable+0x12/0x160 SS:ESP  0068:c6cc9ed0

We think the following patch solves the issue.

Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 09:06:54 +02:00
Dmitry Adamushko
20b6331bfe sched: rework of "prioritize non-migratable tasks over migratable ones"
regarding this commit: 45c01e8249

I think we can do it simpler. Please take a look at the patch below.

Instead of having 2 separate arrays (which is + ~800 bytes on x86_32 and
twice so on x86_64), let's add "exclusive" (the ones that are bound to
this CPU) tasks to the head of the queue and "shared" ones -- to the
end.

In case of a few newly woken up "exclusive" tasks, they are 'stacked'
(not queued as now), meaning that a task {i+1} is being placed in front
of the previously woken up task {i}. But I don't think that this
behavior may cause any realistic problems.

There are a couple of changes on top of this one.

(1) in check_preempt_curr_rt()

I don't think there is a need for the "pick_next_rt_entity(rq, &rq->rt)
!= &rq->curr->rt" check.

enqueue_task_rt(p) and check_preempt_curr_rt() are always called one
after another with rq->lock being held so the following check
"p->rt.nr_cpus_allowed == 1 && rq->curr->rt.nr_cpus_allowed != 1" should
be enough (well, just its left part) to guarantee that 'p' has been
queued in front of the 'curr'.

(2) in set_cpus_allowed_rt()

I don't thinks there is a need for requeue_task_rt() here.

Perhaps, the only case when 'requeue' (+ reschedule) might be useful is
as follows:

i) weight == 1 && cpu_isset(task_cpu(p), *new_mask)

i.e. a task is being bound to this CPU);

ii) 'p' != rq->curr

but here, 'p' has already been on this CPU for a while and was not
migrated. i.e. it's possible that 'rq->curr' would not have high chances
to be migrated right at this particular moment (although, has chance in
a bit longer term), should we allow it to be preempted.

Anyway, I think we should not perhaps make it more complex trying to
address some rare corner cases. For instance, that's why a single queue
approach would be preferable. Unless I'm missing something obvious, this
approach gives us similar functionality at lower cost.

Verified only compilation-wise.

(Almost)-Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-18 12:41:18 +02:00
Rabin Vincent
95e904c7da sched: fix defined-but-unused warning
Fix this warning, which appears with !CONFIG_SMP:
kernel/sched.c:1216: warning: `init_hrtick' defined but not used

Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-17 10:36:58 +02:00
Ingo Molnar
9583f3d9c0 Merge branch 'linus' into core/softirq 2008-06-16 11:24:17 +02:00
Ingo Molnar
e765ee90da Merge branch 'linus' into tracing/ftrace 2008-06-16 11:15:58 +02:00
Ingo Molnar
f9e8e07e07 Merge branch 'linus' into sched-devel 2008-06-16 11:15:21 +02:00
Lai Jiangshan
7a232e0350 sched: 64-bit: fix arithmetics overflow
(overflow means weight >= 2^32 here, because inv_weigh = 2^32/weight)

A weight of a cfs_rq is the sum of weights of which entities
are queued on this cfs_rq, so it will overflow when there are
too many entities.

Although, overflow occurs very rarely, but it break fairness when
it occurs. 64-bits systems have more memory than 32-bit systems
and 64-bit systems can create more process usually, so overflow may
occur more frequently.

This patch guarantees fairness when overflow happens on 64-bit systems.
Thanks to the optimization of compiler, it changes nothing on 32-bit.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-12 14:29:54 +02:00
Lai Jiangshan
2e084786f6 sched: fair group: fix overflow(was: fix divide by zero)
I found a bug which can be reproduced by this way:(linux-2.6.26-rc5, x86-64)
(use 2^32, 2^33, ...., 2^63 as shares value)

# mkdir /dev/cpuctl
# mount -t cgroup -o cpu cpuctl /dev/cpuctl
# cd /dev/cpuctl
# mkdir sub
# echo 0x8000000000000000 > sub/cpu.shares
# echo $$ > sub/tasks
oops here! divide by zero.

This is because do_div() expects the 2th parameter to be 32 bits,
but unsigned long is 64 bits in x86_64.

Peter Zijstra pointed it out that the sane thing to do is limit the
shares value to something smaller instead of using an even more
expensive divide.

Also, I found another bug about "the shares value is too large":

pid1 and pid2 are set affinity to cpu#0
pid1 is attached to cg1 and pid2 is attached to cg2

if cg1/cpu.shares = 1024 cg2/cpu.shares = 2000000000
then pid2 got 100% usage of cpu, and pid1 0%

if cg1/cpu.shares = 1024 cg2/cpu.shares = 20000000000
then pid2 got 0% usage of cpu, and pid1 100%

And a weight of a cfs_rq is the sum of weights of which entities
are queued on this cfs_rq, so the shares value should be limited
to a smaller value.

I think that (1UL << 18) is a good limited value:

1) it's not too large, we can create a lot of group before overflow
2) it's several times the weight value for nice=-19 (not too small)

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-12 14:23:55 +02:00
Ingo Molnar
040ec23d07 sched: sched_clock() lockdep fix
Sitsofe Wheeler bisected the following commit to cause a lockdep to
warn about itself and turn itself off:

> commit c6531cce6e
> Author: Ingo Molnar <mingo@elte.hu>
> Date:   Mon May 12 21:21:14 2008 +0200
>
>     sched: do not trace sched_clock

do not use raw irq flags in cpu_clock() as it causes lockdep to lose
track of the true state of the IRQ flag.

Reported-and-bisected-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2008-06-10 14:52:14 +02:00
Paul Mundt
e9886ca3a9 sched: kill off dead cfs_rq_set_shares()
Building with CONFIG_FAIR_GROUP_SCHED=y on UP results in an unused
cfs_rq_set_shares() reference. As nothing is using this dummy function
in the first place, just kill it off.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-10 14:51:04 +02:00
David Rientjes
9985b0bab3 sched: prevent bound kthreads from changing cpus_allowed
Kthreads that have called kthread_bind() are bound to specific cpus, so
other tasks should not be able to change their cpus_allowed from under
them.  Otherwise, it is possible to move kthreads, such as the migration
or software watchdog threads, so they are not allowed access to the cpu
they work on.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-10 12:26:16 +02:00
Peter Zijlstra
7def2be1dc sched: fix hotplug cpus on ia64
Cliff Wickman wrote:

> I built an ia64 kernel from Andrew's tree (2.6.26-rc2-mm1)
> and get a very predictable hotplug cpu problem.
> billberry1:/tmp/cpw # ./dis
> disabled cpu 17
> enabled cpu 17
> billberry1:/tmp/cpw # ./dis
> disabled cpu 17
> enabled cpu 17
> billberry1:/tmp/cpw # ./dis
>
> The script that disables the cpu always hangs (unkillable)
> on the 3rd attempt.
>
> And a bit further:
> The kstopmachine thread always sits on the run queue (real time) for about
> 30 minutes before running.

this fix solves some (but not all) issues between CPU hotplug and
RT bandwidth throttling.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-10 12:17:28 +02:00
Oleg Nesterov
16882c1e96 sched: fix TASK_WAKEKILL vs SIGKILL race
schedule() has the special "TASK_INTERRUPTIBLE && signal_pending()" case,
this allows us to do

	current->state = TASK_INTERRUPTIBLE;
	schedule();

without fear to sleep with pending signal.

However, the code like

	current->state = TASK_KILLABLE;
	schedule();

is not right, schedule() doesn't take TASK_WAKEKILL into account. This means
that mutex_lock_killable(), wait_for_completion_killable(), down_killable(),
schedule_timeout_killable() can miss SIGKILL (and btw the second SIGKILL has
no effect).

Introduce the new helper, signal_pending_state(), and change schedule() to
use it. Hopefully it will have more users, that is why the task's state is
passed separately.

Note this "__TASK_STOPPED | __TASK_TRACED" check in signal_pending_state().
This is needed to preserve the current behaviour (ptrace_notify). I hope
this check will be removed soon, but this (afaics good) change needs the
separate discussion.

The fast path is "(state & (INTERRUPTIBLE | WAKEKILL)) + signal_pending(p)",
basically the same that schedule() does now. However, this patch of course
bloats schedule().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-10 11:37:25 +02:00
Thomas Gleixner
e958b36004 sched: move weighted_cpuload into #ifdef CONFIG_SMP section
weighted_cpuload is only used on SMP. move it into the CONFIG_SMP
section.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:25:02 +02:00
Max Krasnyansky
68f4f1ec08 sched: Move cpu masks from kernel/sched.c into kernel/cpu.c
kernel/cpu.c seems a more logical place for those maps since they do not really
have much to do with the scheduler these days.

kernel/cpu.c is now built for the UP kernel too, but it does not affect the size
the kernel sections.

$ size vmlinux

before
   text       data        bss        dec        hex    filename
3313797     307060     310352    3931209     3bfc49    vmlinux

after
   text       data        bss        dec        hex    filename
3313797     307060     310352    3931209     3bfc49    vmlinux

Signed-off-by: Max Krasnyansky <maxk@qualcomm.com>
Cc: pj@sgi.com
Cc: menage@google.com
Cc: rostedt@goodmis.org
Cc: mingo@elte.hu
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:25:01 +02:00
Max Krasnyansky
5c8e1ed1d2 sched: CPU hotplug events must not destroy scheduler domains created by the cpusets
First issue is not related to the cpusets. We're simply leaking doms_cur.
It's allocated in arch_init_sched_domains() which is called for every
hotplug event. So we just keep reallocation doms_cur without freeing it.
I introduced free_sched_domains() function that cleans things up.

Second issue is that sched domains created by the cpusets are
completely destroyed by the CPU hotplug events. For all CPU hotplug
events scheduler attaches all CPUs to the NULL domain and then puts
them all into the single domain thereby destroying domains created
by the cpusets (partition_sched_domains).
The solution is simple, when cpusets are enabled scheduler should not
create default domain and instead let cpusets do that. Which is
exactly what the patch does.

Signed-off-by: Max Krasnyansky <maxk@qualcomm.com>
Cc: pj@sgi.com
Cc: menage@google.com
Cc: rostedt@goodmis.org
Cc: mingo@elte.hu
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:25:00 +02:00
Gregory Haskins
1f11eb6a8b sched: fix cpupri hotplug support
The RT folks over at RedHat found an issue w.r.t. hotplug support which
was traced to problems with the cpupri infrastructure in the scheduler:

https://bugzilla.redhat.com/show_bug.cgi?id=449676

This bug affects 23-rt12+, 24-rtX, 25-rtX, and sched-devel.  This patch
applies to 25.4-rt4, though it should trivially apply to most cpupri enabled
kernels mentioned above.

It turned out that the issue was that offline cpus could get inadvertently
registered with cpupri so that they were erroneously selected during
migration decisions.  The end result would be an OOPS as the offline cpu
had tasks routed to it.

This patch generalizes the old join/leave domain interface into an
online/offline interface, and adjusts the root-domain/hotplug code to
utilize it.

I was able to easily reproduce the issue prior to this patch, and am no
longer able to reproduce it after this patch.  I can offline cpus
indefinately and everything seems to be in working order.

Thanks to Arnaldo (acme), Thomas, and Peter for doing the legwork to point
me in the right direction.  Also thank you to Peter for reviewing the
early iterations of this patch.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:19:42 +02:00
Gautham R Shenoy
099f98c8a1 sched: print the sd->level in sched_domain_debug code
While printing out the visual representation of the sched-domains, print
the level (MC, SMT, CPU, NODE, ... ) of each of the sched_domains.

Credit: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-06 15:19:41 +02:00
Dhaval Giani
6d6bc0ad86 sched: add comments for ifdefs in sched.c
make sched.c easier to read.

Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:19:38 +02:00
Arjan van de Ven
e21f5b153b sched: print module list in the "scheduling while atomic" warning
For the normal WARN_ON() etc we added a print-the-modules-list already,
which is very useful to figure out candidates for certain types of bugs.

This patch adds the same print to the "scheduling while atomic" BUG warning,
for the same reason: when we get here it's very useful to see which modules
are loaded, to narrow down the candidate code list.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: mingo@elte.hu
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:19:37 +02:00
Rabin Vincent
81d41d7ece sched: fix defined-but-unused warning
Fix this warning, which appears with !CONFIG_SMP:
kernel/sched.c:1216: warning: `init_hrtick' defined but not used

Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:19:34 +02:00
Thomas Gleixner
f7dcd80bbc namespacecheck: fixes in kernel/sched.c
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:19:32 +02:00
Dmitry Adamushko
d07355f5de sched: check for SD_SERIALIZE atomically in rebalance_domains()
Nothing really serious here, mainly just a matter of nit-picking :-/

From: Dmitry Adamushko <dmitry.adamushko@gmail.com>
For CONFIG_SCHED_DEBUG && CONFIG_SYSCT configs, sd->flags can be altered
while being manipulated in rebalance_domains(). Let's do an atomic check.
We rely here on the atomicity of read/write accesses for aligned words.

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:19:30 +02:00
Gregory Haskins
6e0534f278 sched: use a 2-d bitmap for searching lowest-pri CPU
The current code use a linear algorithm which causes scaling issues
on larger SMP machines.  This patch replaces that algorithm with a
2-dimensional bitmap to reduce latencies in the wake-up path.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:19:28 +02:00
Mike Galbraith
f333fdc909 sched: make !hrtick faster
it is safe to ignore timers and flags when the feature is disabled.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:19:27 +02:00
Gregory Haskins
45c01e8249 sched: prioritize non-migratable tasks over migratable ones
Dmitry Adamushko pointed out a known flaw in the rt-balancing algorithm
that could allow suboptimal balancing if a non-migratable task gets
queued behind a running migratable one.  It is discussed in this thread:

http://lkml.org/lkml/2008/4/22/296

This issue has been further exacerbated by a recent checkin to
sched-devel (git-id 5eee63a5ebc19a870ac40055c0be49457f3a89a3).

>From a pure priority standpoint, the run-queue is doing the "right"
thing. Using Dmitry's nomenclature, if T0 is on cpu1 first, and T1
wakes up at equal or lower priority (affined only to cpu1) later, it
*should* wait for T0 to finish.  However, in reality that is likely
suboptimal from a system perspective if there are other cores that
could allow T0 and T1 to run concurrently.  Since T1 can not migrate,
the only choice for higher concurrency is to try to move T0.  This is
not something we addessed in the recent rt-balancing re-work.

This patch tries to enhance the balancing algorithm by accomodating this
scenario.  It accomplishes this by incorporating the migratability of a
task into its priority calculation.  Within a numerical tsk->prio, a
non-migratable task is logically higher than a migratable one.  We
maintain this by introducing a new per-priority queue (xqueue, or
exclusive-queue) for holding non-migratable tasks.  The scheduler will
draw from the xqueue over the standard shared-queue (squeue) when
available.

There are several details for utilizing this properly.

1) During task-wake-up, we not only need to check if the priority
   preempts the current task, but we also need to check for this
   non-migratable condition.  Therefore, if a non-migratable task wakes
   up and sees an equal priority migratable task already running, it
   will attempt to preempt it *if* there is a likelyhood that the
   current task will find an immediate home.

2) Tasks only get this non-migratable "priority boost" on wake-up.  Any
   requeuing will result in the non-migratable task being queued to the
   end of the shared queue.  This is an attempt to prevent the system
   from being completely unfair to migratable tasks during things like
   SCHED_RR timeslicing.

I am sure this patch introduces potentially "odd" behavior if you
concoct a scenario where a bunch of non-migratable threads could starve
migratable ones given the right pattern.  I am not yet convinced that
this is a problem since we are talking about tasks of equal RT priority
anyway, and there never is much in the way of guarantees against
starvation under that scenario anyway. (e.g. you could come up with a
similar scenario with a specific timing environment verses an affinity
environment).  I can be convinced otherwise, but for now I think this is
"ok".

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
CC: Dmitry Adamushko <dmitry.adamushko@gmail.com>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-06 15:19:25 +02:00
Ingo Molnar
6363ca57c7 revert ("sched: fair-group: SMP-nice for group scheduling")
Yanmin Zhang reported:

Comparing with 2.6.25, volanoMark has big regression with kernel 2.6.26-rc1.
It's about 50% on my 8-core stoakley, 16-core tigerton, and Itanium Montecito.

With bisect, I located the following patch:

| 18d95a2832 is first bad commit
| commit 18d95a2832
| Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
| Date:   Sat Apr 19 19:45:00 2008 +0200
|
|     sched: fair-group: SMP-nice for group scheduling

Revert it so that we get v2.6.25 behavior.

Bisected-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29 11:28:57 +02:00
Ingo Molnar
4285f594f8 sched: cleanup
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29 11:25:15 +02:00
Roel Kluin
3f33a7ce95 sched: unite unlikely pairs in rt_policy() and schedule_debug()
Removes obfuscation and may improve assembly.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29 11:25:14 +02:00
Ingo Molnar
f9305d4a09 revert ("sched: fair: weight calculations")
Yanmin Zhang reported:

Comparing with kernel 2.6.25, sysbench+mysql(oltp, readonly) has many
regressions with 2.6.26-rc1:

 1) 8-core stoakley: 28%;
 2) 16-core tigerton: 20%;
 3) Itanium Montvale: 50%.

Bisect located this patch:

| 8f1bc385cf is first bad commit
| commit 8f1bc385cf
| Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
| Date:   Sat Apr 19 19:45:00 2008 +0200
|
|     sched: fair: weight calculations

Revert it to the 2.6.25 state.

Bisected-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29 11:24:01 +02:00
Ingo Molnar
c6531cce6e sched: do not trace sched_clock
The tracer uses sched_clock, so do not trace it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-25 16:02:23 +02:00
Carlos R. Mafra
962cf36c5b Remove argument from open_softirq which is always NULL
As git-grep shows, open_softirq() is always called with the last argument
being NULL

block/blk-core.c:       open_softirq(BLOCK_SOFTIRQ, blk_done_softirq, NULL);
kernel/hrtimer.c:       open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq, NULL);
kernel/rcuclassic.c:    open_softirq(RCU_SOFTIRQ, rcu_process_callbacks, NULL);
kernel/rcupreempt.c:    open_softirq(RCU_SOFTIRQ, rcu_process_callbacks, NULL);
kernel/sched.c: open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL);
kernel/softirq.c:       open_softirq(TASKLET_SOFTIRQ, tasklet_action, NULL);
kernel/softirq.c:       open_softirq(HI_SOFTIRQ, tasklet_hi_action, NULL);
kernel/timer.c: open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
net/core/dev.c: open_softirq(NET_TX_SOFTIRQ, net_tx_action, NULL);
net/core/dev.c: open_softirq(NET_RX_SOFTIRQ, net_rx_action, NULL);

This observation has already been made by Matthew Wilcox in June 2002
(http://www.cs.helsinki.fi/linux/linux-kernel/2002-25/0687.html)

"I notice that none of the current softirq routines use the data element
passed to them."

and the situation hasn't changed since them. So it appears we can safely
remove that extra argument to save 128 (54) bytes of kernel data (text).

Signed-off-by: Carlos R. Mafra <crmafra@ift.unesp.br>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-25 07:43:15 +02:00
Mathieu Desnoyers
5b82a1b08a Port ftrace to markers
Porting ftrace to the marker infrastructure.

Don't need to chain to the wakeup tracer from the sched tracer, because markers
support multiple probes connected.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 22:29:25 +02:00
Ingo Molnar
4d9493c90f ftrace: remove add-hoc code
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:13:32 +02:00
Peter Zijlstra
5429db2d26 ftrace: fix wakeup callback
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:09:02 +02:00
Ingo Molnar
36fc25a9f4 ftrace: sched tree fix
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:08:28 +02:00
Ingo Molnar
017730c112 ftrace: fix wakeups
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:05:02 +02:00
Ingo Molnar
24cd5d111e ftrace: trace curr/next tasks
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:04:51 +02:00
Ingo Molnar
4e65551905 ftrace: sched tracer, trace full rbtree
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:04:44 +02:00
Ingo Molnar
8ac0fca4cc ftrace: sched tracer fix
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:04:28 +02:00
Steven Rostedt
6cd8a4bb2f ftrace: trace preempt off critical timings
Add preempt off timings. A lot of kernel core code is taken from the RT patch
latency trace that was written by Ingo Molnar.

This adds "preemptoff" and "preemptirqsoff" to /debugfs/tracing/available_tracers

Now instead of just tracing irqs off, preemption off can be selected
to be recorded.

When this is selected, it shares the same files as irqs off timings.
One can either trace preemption off, irqs off, or one or the other off.

By echoing "preemptoff" into /debugfs/tracing/current_tracer, recording
of preempt off only is performed. "irqsoff" will only record the time
irqs are disabled, but "preemptirqsoff" will take the total time irqs
or preemption are disabled. Runtime switching of these options is now
supported by simpling echoing in the appropriate trace name into
/debugfs/tracing/current_tracer.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:32:54 +02:00
Steven Rostedt
7c731e0a49 ftrace: make the task state char-string visible to all
The tracer wants to be able to convert the state number
into a user visible character. This patch pulls that conversion
string out the scheduler into the header. This way if it were to
ever change, other parts of the kernel will know.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:31:05 +02:00
Ingo Molnar
bd3bff9e20 sched: add latency tracer callbacks to the scheduler
add 3 lightweight callbacks to the tracer backend.

zero impact if tracing is turned off.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:30:55 +02:00
Mike Travis
363ab6f142 core: use performance variant for_each_cpu_mask_nr
Change references from for_each_cpu_mask to for_each_cpu_mask_nr
where appropriate

Reviewed-by: Paul Jackson <pj@sgi.com>
Reviewed-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 18:35:12 +02:00
Mike Travis
a953e4597a sched: replace MAX_NUMNODES with nr_node_ids in kernel/sched.c
* Replace usages of MAX_NUMNODES with nr_node_ids in kernel/sched.c,
    where appropriate.  This saves some allocated space as well as many
    wasted cycles going through node entries that are non-existent.

For inclusion into sched-devel/latest tree.

Based on:
	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
    +   sched-devel/latest  .../mingo/linux-2.6-sched-devel.git

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-23 18:22:17 +02:00
Mirco Tischler
0c70814c31 cgroups: fix compile warning
Return type of cpu_rt_runtime_write() should be int instead of ssize_t.

Signed-off-by: Mirco Tischler <mt-ml@gmx.de>
Acked-by: Paul Menage <menage@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-14 19:11:14 -07:00
Linus Torvalds
c3921ab715 Add new 'cond_resched_bkl()' helper function
It acts exactly like a regular 'cond_resched()', but will not get
optimized away when CONFIG_PREEMPT is set.

Normal kernel code is already preemptable in the presense of
CONFIG_PREEMPT, so cond_resched() is optimized away (see commit
02b67cc3ba "sched: do not do
cond_resched() when CONFIG_PREEMPT").

But when wanting to conditionally reschedule while holding a lock, you
need to use "cond_sched_lock(lock)", and the new function is the BKL
equivalent of that.

Also make fs/locks.c use it.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-11 16:04:48 -07:00
Linus Torvalds
8e3e076c5a BKL: revert back to the old spinlock implementation
The generic semaphore rewrite had a huge performance regression on AIM7
(and potentially other BKL-heavy benchmarks) because the generic
semaphores had been rewritten to be simple to understand and fair.  The
latter, in particular, turns a semaphore-based BKL implementation into a
mess of scheduling.

The attempt to fix the performance regression failed miserably (see the
previous commit 00b41ec261 'Revert
"semaphore: fix"'), and so for now the simple and sane approach is to
instead just go back to the old spinlock-based BKL implementation that
never had any issues like this.

This patch also has the advantage of being reported to fix the
regression completely according to Yanmin Zhang, unlike the semaphore
hack which still left a couple percentage point regression.

As a spinlock, the BKL obviously has the potential to be a latency
issue, but it's not really any different from any other spinlock in that
respect.  We do want to get rid of the BKL asap, but that has been the
plan for several years.

These days, the biggest users are in the tty layer (open/release in
particular) and Alan holds out some hope:

  "tty release is probably a few months away from getting cured - I'm
   afraid it will almost certainly be the very last user of the BKL in
   tty to get fixed as it depends on everything else being sanely locked."

so while we're not there yet, we do have a plan of action.

Tested-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Alexander Viro <viro@ftp.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-10 20:58:02 -07:00
Peter Zijlstra
3e51f33fcc sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
this replaces the rq->clock stuff (and possibly cpu_clock()).

 - architectures that have an 'imperfect' hardware clock can set
   CONFIG_HAVE_UNSTABLE_SCHED_CLOCK

 - the 'jiffie' window might be superfulous when we update tick_gtod
   before the __update_sched_clock() call in sched_clock_tick()

 - cpu_clock() might be implemented as:

     sched_clock_cpu(smp_processor_id())

   if the accuracy proves good enough - how far can TSC drift in a
   single jiffie when considering the filtering and idle hooks?

[ mingo@elte.hu: various fixes and cleanups ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-05 23:56:18 +02:00
Ingo Molnar
dfbf4a1bc3 sched: fix cpu clock
David Miller pointed it out that nothing in cpu_clock() sets
prev_cpu_time. This caused __sync_cpu_clock() to be called
all the time - against the intention of this code.

The result was that in practice we hit a global spinlock every
time cpu_clock() is called - which - even though cpu_clock()
is used for tracing and debugging, is suboptimal.

While at it, also:

- move the irq disabling to the outest layer,
  this should make cpu_clock() warp-free when called with irqs
  enabled.

- use long long instead of cycles_t - for platforms where cycles_t
  is 32-bit.

Reported-by: David Miller <davem@davemloft.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-05 23:56:18 +02:00
Miao Xie
cb4ad1ffc7 sched: fair-group: fix a Div0 error of the fair group scheduler
When I echoed 0 into the "cpu.shares" file, a Div0 error occured.

We found it is caused by the following calling.

   sched_group_set_shares(tg, shares)
       set_se_shares(tg->se[i], shares/nr_cpu_ids)
           __set_se_shares(se, shares)
               div64_64((1ULL<<32), shares)

When the echoed value was less than the number of processores, the result of the
sentence "shares/nr_cpu_ids" was 0, and then the system called div64() to divide
the result, the Div0 error occured.

It is unnecessary that the shares value is divided by nr_cpu_ids, I think.
Because in the function  __update_group_shares_cpu() and init_tg_cfs_entry(),
the shares value isn't divided by nr_cpu_ids when setting shares of the sched
entity.

This patch fixes this bug. And echoing ULONG_MAX value into cpu.shares also
causes Div0 error, so we set a macro MAX_SHARES to limit the max value of
shares.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-05 23:56:18 +02:00
Heiko Carstens
712555ee4f sched: fix missing locking in sched_domains code
Concurrent calls to detach_destroy_domains and arch_init_sched_domains
were prevented by the old scheduler subsystem cpu hotplug mutex. When
this got converted to get_online_cpus() the locking got broken.
Unlike before now several processes can concurrently enter the critical
sections that were protected by the old lock.

So use the already present doms_cur_mutex to protect these sections again.

Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-05 23:56:18 +02:00
Ingo Molnar
690229a091 sched: make clock sync tunable by architecture code
make time_sync_thresh tunable to architecture code.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-05 23:56:18 +02:00
David Simner
673a90a1e0 sched: fix sched_info_switch not being called according to documentation
http://bugzilla.kernel.org/show_bug.cgi?id=10545

sched_stats.h says that __sched_info_switch is "called when prev !=
next" in the comment.  sched.c should therefore do that.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-05 23:56:18 +02:00
Peter Zijlstra
b328ca182f sched: fix hrtick_start_fair and CPU-Hotplug
Gautham R Shenoy reported:

 > While running the usual CPU-Hotplug stress tests on linux-2.6.25,
 > I noticed the following in the console logs.
 >
 > This is a wee bit difficult to reproduce. In the past 10 runs I hit this
 > only once.
 >
 > ------------[ cut here ]------------
 >
 > WARNING: at kernel/sched.c:962 hrtick+0x2e/0x65()
 >
 > Just wondering if we are doing a good job at handling the cancellation
 > of any per-cpu scheduler timers during CPU-Hotplug.

This looks like its indeed not cancelled at all and migrates the it to
another cpu. Fix it via a proper hotplug notifier mechanism.

Reported-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-05 23:56:18 +02:00
Harvey Harrison
983ed7a66b sched: add statics, don't return void expressions
Noticed by sparse:
kernel/sched.c:760:20: warning: symbol 'sched_feat_names' was not declared. Should it be static?
kernel/sched.c:767:5: warning: symbol 'sched_feat_open' was not declared. Should it be static?
kernel/sched_fair.c:845:3: warning: returning void-valued expression
kernel/sched.c:4386:3: warning: returning void-valued expression

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-05 23:56:17 +02:00
Andrew Morton
d478c2cfaa sched: add debug checks to idle functions
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: "Justin Mattock" <justinmattock@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-05 23:56:17 +02:00
Peter Zijlstra
e05510d01a sched: optimize calc_delta_mine()
Joel noticed that the !lw->inv_weight contition isn't unlikely anymore so
remove the unlikely annotation. Also, remove the two div64_u64() inv_weight
calculations, which makes them rely on the calc_delta_mine() path as well.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Joel Schopp <jschopp@austin.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-05 23:56:17 +02:00
Roman Zippel
6f6d6a1a6a rename div64_64 to div64_u64
Rename div64_64 to div64_u64 to make it consistent with the other divide
functions, so it clearly includes the type of the divide.  Move its definition
to math64.h as currently no architecture overrides the generic implementation.
 They can still override it of course, but the duplicated declarations are
avoided.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: Avi Kivity <avi@qumranet.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-01 08:03:58 -07:00
Paul Menage
06ecb27cfb CGroups _s64 files: use read_s64/write_s64 in CFS cgroup for rt_runtime file
This removes some filesystem boilerplate from the CFS cgroup subsystem.

Signed-off-by: Paul Menage <menage@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 08:06:09 -07:00
Paul Menage
f4c753b7ea CGroup API files: rename read/write_uint methods to read_write_u64
Several people have justifiably complained that the "_uint" suffix is
inappropriate for functions that handle u64 values, so this patch just renames
all these functions and their users to have the suffic _u64.

[peterz@infradead.org: build fix]
Signed-off-by: Paul Menage <menage@google.com>
Cc: "Li Zefan" <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "YAMAMOTO Takashi" <yamamoto@valinux.co.jp>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 08:06:07 -07:00
Linus Torvalds
6e18933f2b Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6:
  [PATCH] Build fix for CONFIG_NUMA=y && CONFIG_SMP=n
  [IA64] fix bootmem regression on Altix
2008-04-25 12:50:00 -07:00
Linus Torvalds
0b79dada97 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-fixes
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-fixes:
  sched: fix share (re)distribution
  softlockup: fix NOHZ wakeup
  seqlock: livelock fix
2008-04-25 12:47:56 -07:00
David Miller
5a9d3225a0 sched: use alloc_bootmem() instead of alloc_bootmem_low()
There is no guarantee that there is physical ram below 4GB, and in
fact many boxes don't have exactly that.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-25 09:53:06 +02:00
Peter Zijlstra
3f5087a2ba sched: fix share (re)distribution
fix __aggregate_redistribute_shares() related lockup reported by
David S. Miller.

The problem this code tries to solve is 'accurately' calculating the 'fair'
share of the group weight for each cpu. The current code falls back to a global
group rebalance in case the sched_domain's span it looks at has no shares, but
does have tasks.

The reason it gets stuck here, is because its inherently racy - if someone
steals the last task after we compute the agg->rq_weight, but before we
rebalance, we'll never get out of the loop.

We could of course go fix that, but while looking at this issue I found that
this 'fallback' wasn't nearly as rare as I'd hoped it to be. In fact its quite
common - and given it walks the whole machine, thats very bad.

The new approach is simple (why didn't I think of it before?), we set the
aggregate shares to the full task group weight, and each larger sched domain
that encounters an aggregate shares larger than the weight, clips it (it
already re-distributes anyway).

This nicely converges to the desired global picture where the sum of all
shares equals the task group weight.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-25 00:25:08 +02:00
Mike Travis
03970f065d [PATCH] Build fix for CONFIG_NUMA=y && CONFIG_SMP=n
Regression caused by 434d53b00d

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2008-04-24 14:40:29 -07:00
Russ Anderson
472613b961 [IA64] fix bootmem regression on Altix
A recent change prevents SGI Altix from booting.
This patch fixes the problem.

The regresson was introduced in commit 434d53b00d

Signed-off-by: Russ Anderson <rja@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2008-04-24 14:21:21 -07:00
Randy Dunlap
73486722b7 kernel-doc: fix sched.c missing parameter
Add missing kernel-doc in kernel/sched.c:

Warning(linux-2.6.25-git3//kernel/sched.c:7044): No description found for parameter 'span'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-22 13:48:02 -07:00
Ingo Molnar
c24b7c5244 sched: features fix
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:45:00 +02:00
Peter Zijlstra
f00b45c145 sched: /debug/sched_features
provide a text based interface to the scheduler features; this saves the
'user' from setting bits using decimal arithmetic.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:45:00 +02:00
Ingo Molnar
06379aba52 sched: add SCHED_FEAT_DEADLINE
unused at the moment.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:45:00 +02:00
Peter Zijlstra
8f1bc385cf sched: fair: weight calculations
In order to level the hierarchy, we need to calculate load based on the
root view. That is, each task's load is in the same unit.

             A
            / \
           B   1
          / \
         2   3

To compute 1's load we do:

	   weight(1)
	--------------
	 rq_weight(A)

To compute 2's load we do:

	  weight(2)      weight(B)
	------------ * -----------
	rq_weight(B)   rw_weight(A)

This yields load fractions in comparable units.

The consequence is that it changes virtual time. We used to have:

                time_{i}
  vtime_{i} = ------------
               weight_{i}

  vtime = \Sum vtime_{i} = time / rq_weight.

But with the new way of load calculation we get that vtime equals time.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:45:00 +02:00
Peter Zijlstra
4a55bd5e97 sched: fair-group: de-couple load-balancing from the rb-trees
De-couple load-balancing from the rb-trees, so that I can change their
organization.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:45:00 +02:00
Peter Zijlstra
18d95a2832 sched: fair-group: SMP-nice for group scheduling
Implement SMP nice support for the full group hierarchy.

On each load-balance action, compile a sched_domain wide view of the full
task_group tree. We compute the domain wide view when walking down the
hierarchy, and readjust the weights when walking back up.

After collecting and readjusting the domain wide view, we try to balance the
tasks within the task_groups. The current approach is a naively balance each
task group until we've moved the targeted amount of load.

Inspired by Srivatsa Vaddsgiri's previous code and Abhishek Chandra's H-SMP
paper.

XXX: there will be some numerical issues due to the limited nature of
     SCHED_LOAD_SCALE wrt to representing a task_groups influence on the
     total weight. When the tree is deep enough, or the task weight small
     enough, we'll run out of bits.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Abhishek Chandra <chandra@cs.umn.edu>
CC: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:45:00 +02:00
Hidetoshi Seto
1d3504fcf5 sched, cpuset: customize sched domains, core
[rebased for sched-devel/latest]

 - Add a new cpuset file, having levels:
     sched_relax_domain_level

 - Modify partition_sched_domains() and build_sched_domains()
   to take attributes parameter passed from cpuset.

 - Fill newidle_idx for node domains which currently unused but
   might be required if sched_relax_domain_level become higher.

 - We can change the default level by boot option 'relax_domain_level='.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:45:00 +02:00
Peter Zijlstra
b40b2e8eb5 sched: rt: multi level group constraints
multi level rt constraints

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:45:00 +02:00
Peter Zijlstra
f473aa5e02 sched: task_group hierarchy
Add the full parent<->child relation thing into task_groups as well.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:45:00 +02:00
Peter Zijlstra
eff766a65c sched: fix the task_group hierarchy for UID grouping
UID grouping doesn't actually have a task_group representing the root of
the task_group tree. Add one.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:45:00 +02:00
Dhaval Giani
ec7dc8ac73 sched: allow the group scheduler to have multiple levels
This patch makes the group scheduler multi hierarchy aware.

[a.p.zijlstra@chello.nl: rt-parts and assorted fixes]
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:59 +02:00
Dhaval Giani
354d60c2ff sched: mix tasks and groups
This patch allows tasks and groups to exist in the same cfs_rq. With this
change the CFS group scheduling follows a 1/(M+N) model from a 1/(1+N)
fairness model where M tasks and N groups exist at the cfs_rq level.

[a.p.zijlstra@chello.nl: rt bits and assorted fixes]
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:59 +02:00
Ingo Molnar
ea736ed5d3 sched: fix checks
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:59 +02:00
Peter Zijlstra
112f53f5d7 sched: old sleeper bonus
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:59 +02:00
Mike Travis
cd8ba7cd9b sched: add new set_cpus_allowed_ptr function
Add a new function that accepts a pointer to the "newly allowed cpus"
cpumask argument.

int set_cpus_allowed_ptr(struct task_struct *p, const cpumask_t *new_mask)

The current set_cpus_allowed() function is modified to use the above
but this does not result in an ABI change.  And with some compiler
optimization help, it may not introduce any additional overhead.

Additionally, to enforce the read only nature of the new_mask arg, the
"const" property is migrated to sub-functions called by set_cpus_allowed.
This silences compiler warnings.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:59 +02:00
Mike Travis
e0982e90cd init: move setup of nr_cpu_ids to as early as possible
Move the setting of nr_cpu_ids from sched_init() to start_kernel()
so that it's available as early as possible.

Note that an arch has the option of setting it even earlier if need be,
but it should not result in a different value than the setup_nr_cpu_ids()
function.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:59 +02:00
Mike Travis
4bdbaad33d sched: remove another cpumask_t variable from stack
* Remove another cpumask_t variable from stack that was missed in the
      last kernel_sched_c updates.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:59 +02:00
Mike Travis
7c16ec585c cpumask: reduce stack usage in SD_x_INIT initializers
* Remove empty cpumask_t (and all non-zero/non-null) variables
    in SD_*_INIT macros.  Use memset(0) to clear.  Also, don't
    inline the initializer functions to save on stack space in
    build_sched_domains().

  * Merge change to include/linux/topology.h that uses the new
    node_to_cpumask_ptr function in the nr_cpus_node macro into
    this patch.

Depends on:
	[mm-patch]: asm-generic-add-node_to_cpumask_ptr-macro.patch
	[sched-devel]: sched: add new set_cpus_allowed_ptr function

Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:59 +02:00
Mike Travis
c5f59f0833 nodemask: use new node_to_cpumask_ptr function
* Use new node_to_cpumask_ptr.  This creates a pointer to the
    cpumask for a given node.  This definition is in mm patch:

	asm-generic-add-node_to_cpumask_ptr-macro.patch

  * Use new set_cpus_allowed_ptr function.

Depends on:
	[mm-patch]: asm-generic-add-node_to_cpumask_ptr-macro.patch
	[sched-devel]: sched: add new set_cpus_allowed_ptr function
	[x86/latest]: x86: add cpus_scnprintf function

Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Greg Banks <gnb@melbourne.sgi.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:59 +02:00
Mike Travis
b53e921ba1 generic: reduce stack pressure in sched_affinity
* Modify sched_affinity functions to pass cpumask_t variables by reference
    instead of by value.

  * Use new set_cpus_allowed_ptr function.

Depends on:
	[sched-devel]: sched: add new set_cpus_allowed_ptr function

Cc: Paul Jackson <pj@sgi.com>
Cc: Cliff Wickman <cpw@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:59 +02:00
Mike Travis
f9a86fcbbb cpuset: modify cpuset_set_cpus_allowed to use cpumask pointer
* Modify cpuset_cpus_allowed to return the currently allowed cpuset
    via a pointer argument instead of as the function return value.

  * Use new set_cpus_allowed_ptr function.

  * Cleanup CPU_MASK_ALL and NODE_MASK_ALL uses.

Depends on:
	[sched-devel]: sched: add new set_cpus_allowed_ptr function

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:58 +02:00
Mike Travis
434d53b00d sched: remove fixed NR_CPUS sized arrays in kernel_sched_c
* Change fixed size arrays to per_cpu variables or dynamically allocated
   arrays in sched_init() and sched_init_smp().

     (1) static struct sched_entity *init_sched_entity_p[NR_CPUS];
     (1) static struct cfs_rq *init_cfs_rq_p[NR_CPUS];
     (1) static struct sched_rt_entity *init_sched_rt_entity_p[NR_CPUS];
     (1) static struct rt_rq *init_rt_rq_p[NR_CPUS];
	 static struct sched_group **sched_group_nodes_bycpu[NR_CPUS];

     (1) - these arrays are allocated via alloc_bootmem_low()

 * Change sched_domain_debug_one() to use cpulist_scnprintf instead of
   cpumask_scnprintf.  This reduces the output buffer required and improves
   readability when large NR_CPU count machines arrive.

 * In sched_create_group() we allocate new arrays based on nr_cpu_ids.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:58 +02:00
Dhaval Giani
0297b80339 sched: allow cpuacct stats to be reset
Currently the schedstats implementation does not allow the statistics
to be reset. This patch aims to allow that.

  echo 0 > cpuacct.usage

resets the usage. Any other value is not allowed and returns -EINVAL.

Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:58 +02:00
Dhaval Giani
32cd756a80 sched: cleanup cpuacct variable names
Change the variable names to the common convention for the cpuacct
subsystem.

Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:58 +02:00
Peter Zijlstra
ac086bc229 sched: rt-group: smp balancing
Currently the rt group scheduling does a per cpu runtime limit, however
the rt load balancer makes no guarantees about an equal spread of real-
time tasks, just that at any one time, the highest priority tasks run.

Solve this by making the runtime limit a global property by borrowing
excessive runtime from the other cpus once the local limit runs out.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:58 +02:00
Peter Zijlstra
d0b27fa778 sched: rt-group: synchonised bandwidth period
Various SMP balancing algorithms require that the bandwidth period
run in sync.

Possible improvements are moving the rt_bandwidth thing into root_domain
and keeping a span per rt_bandwidth which marks throttled cpus.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:57 +02:00
Ingo Molnar
50df5d6aea sched: remove sysctl_sched_batch_wakeup_granularity
it's unused.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:57 +02:00
Ingo Molnar
02e2b83bd2 sched: reenable sync wakeups
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:57 +02:00
Ingo Molnar
d25ce4cd49 sched: cache hot buddy
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:57 +02:00
Ingo Molnar
1fc8afa4c8 sched: feat affine wakeups
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:57 +02:00
Ingo Molnar
b85d066726 sched: introduce SCHED_FEAT_SYNC_WAKEUPS, turn it off
turn off sync wakeups by default. They are not needed anymore - the
buddy logic should be smart enough to keep the system from
overscheduling.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:57 +02:00
Guillaume Chazarain
15934a3732 sched: fix rq->clock overflows detection with CONFIG_NO_HZ
When using CONFIG_NO_HZ, rq->tick_timestamp is not updated every TICK_NSEC.
We check that the number of skipped ticks matches the clock jump seen in
__update_rq_clock().

Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:57 +02:00
Reynes Philippe
30914a58af sched: sched.c needs tick.h
kernel/sched.c:506: erreur: implicit declaration of function tick_get_tick_sched
kernel/sched.c:506: erreur: invalid type argument of ->
kernel/sched.c:506: erreur: NOHZ_MODE_INACTIVE undeclared (first use in this function)
kernel/sched.c:506: erreur: (Each undeclared identifier is reported only once
kernel/sched.c:506: erreur: for each function it appears in.)

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:57 +02:00
Ingo Molnar
27ec440779 sched: make cpu_clock() globally synchronous
Alexey Zaytsev reported (and bisected) that the introduction of
cpu_clock() in printk made the timestamps jump back and forth.

Make cpu_clock() more reliable while still keeping it fast when it's
called frequently.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19 19:44:57 +02:00
Thomas Gleixner
06d8308c61 NOHZ: reevaluate idle sleep length after add_timer_on()
add_timer_on() can add a timer on a CPU which is currently in a long
idle sleep, but the timer wheel is not reevaluated by the nohz code on
that CPU. So a timer can be delayed for quite a long time. This
triggered a false positive in the clocksource watchdog code.

To avoid this we need to wake up the idle CPU and enforce the
reevaluation of the timer wheel for the next timer event.

Add a function, which checks a given CPU for idle state, marks the
idle task with NEED_RESCHED and sends a reschedule IPI to notify the
other CPU of the change in the timer wheel.

Call this function from add_timer_on().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: stable@kernel.org

--
 include/linux/sched.h |    6 ++++++
 kernel/sched.c        |   43 +++++++++++++++++++++++++++++++++++++++++++
 kernel/timer.c        |   10 +++++++++-
 3 files changed, 58 insertions(+), 1 deletion(-)
2008-03-26 08:28:55 +01:00
Heiko Carstens
22e52b072d sched: add arch_update_cpu_topology hook.
Will be called each time the scheduling domains are rebuild.
Needed for architectures that don't have a static cpu topology.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-21 16:43:48 +01:00
Heiko Carstens
9aefd0abd8 sched: add exported arch_reinit_sched_domains() to header file.
Needed so it can be called from outside of sched.c.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-21 16:43:47 +01:00
Roel Kluin
23e3c3cd2e sched: remove double unlikely from schedule()
Combine two unlikely's

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-21 16:43:47 +01:00
Peter Zijlstra
2070ee01d3 sched: cleanup old and rarely used 'debug' features.
TREE_AVG and APPROX_AVG are initial task placement policies that have been
disabled for a long while.. time to remove them.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-21 16:43:47 +01:00
Ingo Molnar
f540a6080a sched: wakeup-buddy tasks are cache-hot
Wakeup-buddy tasks are cache-hot - this makes it a bit harder
for the load-balancer to tear them apart. (but it's still possible,
if the load is sufficiently assymetric)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-19 04:27:53 +01:00
Ingo Molnar
4ae7d5cefd sched: improve affine wakeups
improve affine wakeups. Maintain the 'overlap' metric based on CFS's
sum_exec_runtime - which means the amount of time a task executes
after it wakes up some other task.

Use the 'overlap' for the wakeup decisions: if the 'overlap' is short,
it means there's strong workload coupling between this task and the
woken up task. If the 'overlap' is large then the workload is decoupled
and the scheduler will move them to separate CPUs more easily.

( Also slightly move the preempt_check within try_to_wake_up() - this has
  no effect on functionality but allows 'early wakeups' (for still-on-rq
  tasks) to be correctly accounted as well.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-19 04:27:53 +01:00
Peter Zijlstra
aa2ac25229 sched: fix overload performance: buddy wakeups
Currently we schedule to the leftmost task in the runqueue. When the
runtimes are very short because of some server/client ping-pong,
especially in over-saturated workloads, this will cycle through all
tasks trashing the cache.

Reduce cache trashing by keeping dependent tasks together by running
newly woken tasks first. However, by not running the leftmost task first
we could starve tasks because the wakee can gain unlimited runtime.

Therefore we only run the wakee if its within a small
(wakeup_granularity) window of the leftmost task. This preserves
fairness, but does alternate server/client task groups.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-15 03:02:50 +01:00
Ingo Molnar
27d1172660 sched: fix calc_delta_mine()
lw->weight can be 0 for a short time during bootup.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2008-03-15 03:02:50 +01:00
Ingo Molnar
e89996ae3f sched: fix update_load_add()/sub()
Clear the cached inverse value when updating load. This is needed for
calc_delta_mine() to work correctly when using the rq load.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2008-03-15 03:02:49 +01:00
Hiroshi Shimamoto
0e1f34833b sched: fix race in schedule()
Fix a hard to trigger crash seen in the -rt kernel that also affects
the vanilla scheduler.

There is a race condition between schedule() and some dequeue/enqueue
functions; rt_mutex_setprio(), __setscheduler() and sched_move_task().

When scheduling to idle, idle_balance() is called to pull tasks from
other busy processor. It might drop the rq lock. It means that those 3
functions encounter on_rq=0 and running=1. The current task should be
put when running.

Here is a possible scenario:

   CPU0                               CPU1
    |                              schedule()
    |                              ->deactivate_task()
    |                              ->idle_balance()
    |                              -->load_balance_newidle()
rt_mutex_setprio()                     |
    |                              --->double_lock_balance()
    *get lock                          *rel lock
    * on_rq=0, ruuning=1               |
    * sched_class is changed           |
    *rel lock                          *get lock
    :                                  |
                                       :
                                   ->put_prev_task_rt()
                                   ->pick_next_task_fair()
                                       => panic

The current process of CPU1(P1) is scheduling. Deactivated P1, and the
scheduler looks for another process on other CPU's runqueue because CPU1
will be idle. idle_balance(), load_balance_newidle() and
double_lock_balance() are called and double_lock_balance() could drop
the rq lock. On the other hand, CPU0 is trying to boost the priority of
P1. The result of boosting only P1's prio and sched_class are changed to
RT. The sched entities of P1 and P1's group are never put. It makes
cfs_rq invalid, because the cfs_rq has curr and no leaf, but
pick_next_task_fair() is called, then the kernel panics.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-15 03:02:49 +01:00
Gregory Haskins
08f503b0c0 keep rd->online and cpu_online_map in sync
It is possible to allow the root-domain cache of online cpus to
become out of sync with the global cpu_online_map.  This is because we
currently trigger removal of cpus too early in the notifier chain.
Other DOWN_PREPARE handlers may in fact run and reconfigure the
root-domain topology, thereby stomping on our own offline handling.

The end result is that rd->online may become out of sync with
cpu_online_map, which results in potential task misrouting.

So change the offline handling to be more tightly coupled with the
global offline process by triggering on CPU_DYING intead of
CPU_DOWN_PREPARE.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-11 14:02:58 +01:00
Gregory Haskins
1f94ef598e Revert "cpu hotplug: adjust root-domain->online span in response to hotplug event"
This reverts commit 393d94d98b.

Lets fix this right.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-11 14:02:58 +01:00
Gregory Haskins
393d94d98b cpu hotplug: adjust root-domain->online span in response to hotplug event
We currently set the root-domain online span automatically when the
domain is added to the cpu if the cpu is already a member of
cpu_online_map.

This was done as a hack/bug-fix for s2ram, but it also causes a problem
with hotplug CPU_DOWN transitioning.  The right way to fix the original
problem is to actually respond to CPU_UP events, instead of CPU_ONLINE,
which is already too late.

This solves the hung reboot regression reported by Andrew Morton and
others.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-09 10:05:14 -07:00
Dhaval Giani
521f1a2489 sched: don't allow rt_runtime_us to be zero for groups having rt tasks
This patch checks if we can set the rt_runtime_us to 0. If there is a
realtime task in the group, we don't want to set the rt_runtime_us as 0
or bad things will happen. (that task wont get any CPU time despite
being TASK_RUNNNG)

Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-07 16:43:00 +01:00
Peter Zijlstra
2692a2406b sched: rt-group: fixup schedulability constraints calculation
it was only possible to configure the rt-group scheduling parameters
beyond the default value in a very small range.

that's because div64_64() has a different calling convention than
do_div() :/

fix a few untidies while we are here; sysctl_sched_rt_period may overflow
due to that multiplication, so cast to u64 first. Also that RUNTIME_INF
juggling makes little sense although its an effective NOP.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-07 16:43:00 +01:00
Miao Xie
1868f958eb sched: fix the wrong time slice value for SCHED_FIFO tasks
Function sys_sched_rr_get_interval returns wrong time slice value for
SCHED_FIFO tasks. The time slice for SCHED_FIFO tasks should be 0.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-07 16:43:00 +01:00
Pavel Roskin
150d8bede7 sched: export task_nice
The API is trivial, and so is the implementation.

Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-07 16:43:00 +01:00
Peter Zijlstra
810b38179e sched: retain vruntime
Kei Tokunaga reported an interactivity problem when moving tasks
between control groups.

Tasks would retain their old vruntime when moved between groups, this
can cause funny lags. Re-set the vruntime on group move to fit within
the new tree.

Reported-by: Kei Tokunaga <tokunaga.keiich@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-07 16:42:59 +01:00
Peter Zijlstra
62fb185130 sched: revert load_balance_monitor() changes
The following commits cause a number of regressions:

  commit 58e2d4ca58
  Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
  Date:   Fri Jan 25 21:08:00 2008 +0100
  sched: group scheduling, change how cpu load is calculated

  commit 6b2d770026
  Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
  Date:   Fri Jan 25 21:08:00 2008 +0100
  sched: group scheduler, fix fairness of cpu bandwidth allocation for task groups

Namely:
 - very frequent wakeups on SMP, reported by PowerTop users.
 - cacheline trashing on (large) SMP
 - some latencies larger than 500ms

While there is a mergeable patch to fix the latter, the former issues
are not fixable in a manner suitable for .25 (we're at -rc3 now).

Hence we revert them and try again in v2.6.26.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Tested-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-04 17:54:06 +01:00
Harvey Harrison
67ca7bde2e sched: fix signedness warnings in sched.c
Unsigned long values are always assigned to switch_count,
make it unsigned long.

kernel/sched.c:3897:15: warning: incorrect type in assignment (different signedness)
kernel/sched.c:3897:15:    expected long *switch_count
kernel/sched.c:3897:15:    got unsigned long *<noident>
kernel/sched.c:3921:16: warning: incorrect type in assignment (different signedness)
kernel/sched.c:3921:16:    expected long *switch_count
kernel/sched.c:3921:16:    got unsigned long *<noident>

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-25 16:34:17 +01:00
Ingo Molnar
6892b75e60 sched: make early bootup sched_clock() use safer
do not call sched_clock() too early. Not only might rq->idle
not be set up - but pure per-cpu data might not be accessible
either.

this solves an ia64 early bootup hang with CONFIG_PRINTK_TIME=y.

Tested-by: Tony Luck <tony.luck@gmail.com>
Acked-by: Tony Luck <tony.luck@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-25 16:34:16 +01:00
Linus Torvalds
04e2f1741d Add memory barrier semantics to wake_up() & co
Oleg Nesterov and others have pointed out that on some architectures,
the traditional sequence of

	set_current_state(TASK_INTERRUPTIBLE);
	if (CONDITION)
		return;
	schedule();

is racy wrt another CPU doing

	CONDITION = 1;
	wake_up_process(p);

because while set_current_state() has a memory barrier separating
setting of the TASK_INTERRUPTIBLE state from reading of the CONDITION
variable, there is no such memory barrier on the wakeup side.

Now, wake_up_process() does actually take a spinlock before it reads and
sets the task state on the waking side, and on x86 (and many other
architectures) that spinlock is in fact equivalent to a memory barrier,
but that is not generally guaranteed.  The write that sets CONDITION
could move into the critical region protected by the runqueue spinlock.

However, adding a smp_wmb() to before the spinlock should now order the
writing of CONDITION wrt the lock itself, which in turn is ordered wrt
the accesses within the spinlock (which includes the reading of the old
state).

This should thus close the race (which probably has never been seen in
practice, but since smp_wmb() is a no-op on x86, it's not like this will
make anything worse either on the most common architecture where the
spinlock already gave the required protection).

Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-23 18:05:03 -08:00
Srinivasa Ds
4362758279 kprobes: refuse kprobe insertion on add/sub_preempt_counter()
Kprobes makes use of preempt_disable(),preempt_enable_noresched() and these
functions inturn call add/sub_preempt_count().  So we need to refuse user from
inserting probe in to these functions.

This patch disallows user from probing add/sub_preempt_count().

Signed-off-by: Srinivasa DS <srinivasa@in.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-23 17:13:24 -08:00
Peter Zijlstra
b68aa2300c sched: rt-group: refure unrunnable tasks
Refuse to accept or create RT tasks in groups that can't run them.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-13 15:45:40 +01:00
Peter Zijlstra
bccbe08a60 sched: rt-group: clean up the ifdeffery
Clean up some of the excessive ifdeffery introduces in the last patch.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-13 15:45:40 +01:00
Peter Zijlstra
052f1dc7eb sched: rt-group: make rt groups scheduling configurable
Make the rt group scheduler compile time configurable.
Keep it experimental for now.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-13 15:45:40 +01:00
Peter Zijlstra
9f0c1e560c sched: rt-group: interface
Change the rt_ratio interface to rt_runtime_us, to match rt_period_us.
This avoids picking a granularity for the ratio.

Extend the /sys/kernel/uids/<uid>/ interface to allow setting
the group's rt_runtime.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-13 15:45:39 +01:00
Peter Zijlstra
23b0fdfc92 sched: rt-group: deal with PI
Steven mentioned the fun case where a lock holding task will be throttled.

Simple fix: allow groups that have boosted tasks to run anyway.

If a runnable task in a throttled group gets boosted the dequeue/enqueue
done by rt_mutex_setprio() is enough to unthrottle the group.

This is ofcourse not quite correct. Two possible ways forward are:
  - second prio array for boosted tasks
  - boost to a prio ceiling (this would also work for deadline scheduling)

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-13 15:45:39 +01:00
Peter Zijlstra
4cf5d77a6e sched: fix incorrect irq lock usage in normalize_rt_tasks()
lockdep spotted this bogus irq locking. normalize_rt_tasks() can be called
from hardirq context through sysrq-n

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-13 15:45:39 +01:00
Peter Zijlstra
8ed3699682 sched: fair-group: separate tg->shares from task_group_lock
On Mon, 2008-02-11 at 15:09 +0300, Denis V. Lunev wrote:
> BUG: sleeping function called from invalid context
> at /home/den/src/linux-netns26/kernel/mutex.c:209
> in_atomic():1, irqs_disabled():0
> no locks held by swapper/0.
> Pid: 0, comm: swapper Not tainted 2.6.24 #304
>
> Call Trace:
>  <IRQ>  [<ffffffff80252d1e>] ? __debug_show_held_locks+0x15/0x27
>  [<ffffffff8022c2a8>] __might_sleep+0xc0/0xdf
>  [<ffffffff8049f1df>] mutex_lock_nested+0x28/0x2a9
>  [<ffffffff80231294>] sched_destroy_group+0x18/0xea
>  [<ffffffff8023e835>] sched_destroy_user+0xd/0xf
>  [<ffffffff8023e8c1>] free_uid+0x8a/0xab
>  [<ffffffff80233e24>] __put_task_struct+0x3f/0xd3
>  [<ffffffff80236708>] delayed_put_task_struct+0x23/0x25
>  [<ffffffff8026fda7>] __rcu_process_callbacks+0x8d/0x215
>  [<ffffffff8026ff52>] rcu_process_callbacks+0x23/0x44
>  [<ffffffff8023a2ae>] __do_softirq+0x79/0xf8
>  [<ffffffff8020f8c3>] ? profile_pc+0x2a/0x67
>  [<ffffffff8020d38c>] call_softirq+0x1c/0x30
>  [<ffffffff8020f689>] do_softirq+0x61/0x9c
>  [<ffffffff8023a233>] irq_exit+0x51/0x53
>  [<ffffffff8021bd1a>] smp_apic_timer_interrupt+0x77/0xad
>  [<ffffffff8020ce3b>] apic_timer_interrupt+0x6b/0x70
>  <EOI>  [<ffffffff8020b0dd>] ? default_idle+0x43/0x76
>  [<ffffffff8020b0db>] ? default_idle+0x41/0x76
>  [<ffffffff8020b09a>] ? default_idle+0x0/0x76
>  [<ffffffff8020b186>] ? cpu_idle+0x76/0x98

separate the tg->shares protection from the task_group lock.

Reported-by: Denis V. Lunev <den@openvz.org>
Tested-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-13 15:45:39 +01:00
Harvey Harrison
7ad5b3a505 kernel: remove fastcall in kernel/*
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 09:22:31 -08:00
Linus Torvalds
75659ca0c1 Merge branch 'task_killable' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc
* 'task_killable' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc: (22 commits)
  Remove commented-out code copied from NFS
  NFS: Switch from intr mount option to TASK_KILLABLE
  Add wait_for_completion_killable
  Add wait_event_killable
  Add schedule_timeout_killable
  Use mutex_lock_killable in vfs_readdir
  Add mutex_lock_killable
  Use lock_page_killable
  Add lock_page_killable
  Add fatal_signal_pending
  Add TASK_WAKEKILL
  exit: Use task_is_*
  signal: Use task_is_*
  sched: Use task_contributes_to_load, TASK_ALL and TASK_NORMAL
  ptrace: Use task_is_*
  power: Use task_is_*
  wait: Use TASK_NORMAL
  proc/base.c: Use task_is_*
  proc/array.c: Use TASK_REPORT
  perfmon: Use task_is_*
  ...

Fixed up conflicts in NFS/sunrpc manually..
2008-02-01 11:45:47 +11:00
Gerald Stralko
5aff0531ee sched: remove unused params
This removes the extra struct task_struct *p parameter in inc_nr_running
and dec_nr_running functions.

Signed-off by: Jerry Stralko <gerb.stralko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-31 22:45:23 +01:00
Nick Piggin
95c354fe9f spinlock: lockbreak cleanup
The break_lock data structure and code for spinlocks is quite nasty.
Not only does it double the size of a spinlock but it changes locking to
a potentially less optimal trylock.

Put all of that under CONFIG_GENERIC_LOCKBREAK, and introduce a
__raw_spin_is_contended that uses the lock data itself to determine whether
there are waiters on the lock, to be used if CONFIG_GENERIC_LOCKBREAK is
not set.

Rename need_lockbreak to spin_needbreak, make it use spin_is_contended to
decouple it from the spinlock implementation, and make it typesafe (rwlocks
do not have any need_lockbreak sites -- why do they even get bloated up
with that break_lock then?).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:31:20 +01:00
Nick Piggin
5fb5e6de55 sched: print backtrace of running tasks too
The attached patch is something really simple that can sometimes help
in getting more info out of a hung system.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:34 +01:00
Guillaume Chazarain
cc203d2422 sched: monitor clock underflows in /proc/sched_debug
We monitor clock overflows, let's also monitor clock underflows.

Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:34 +01:00
Guillaume Chazarain
782daeee3d sched: fix rq->clock warps on frequency changes
sched: fix rq->clock warps on frequency changes

Fix 2bacec8c31
(sched: touch softlockup watchdog after idling) that reintroduced warps
on frequency changes. touch_softlockup_watchdog() calls __update_rq_clock
that checks rq->clock for warps, so call it after adjusting rq->clock.

Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:33 +01:00
Ingo Molnar
6478d8800b sched: remove the !PREEMPT_BKL code
remove the !PREEMPT_BKL code.

this removes 160 lines of legacy code.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:33 +01:00
Peter Zijlstra
48d5e25821 sched: rt throttling vs no_hz
We need to teach no_hz about the rt throttling because its tick driven.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:31 +01:00
Peter Zijlstra
6f505b1642 sched: rt group scheduling
Extend group scheduling to also cover the realtime classes. It uses the time
limiting introduced by the previous patch to allow multiple realtime groups.

The hard time limit is required to keep behaviour deterministic.

The algorithms used make the realtime scheduler O(tg), linear scaling wrt the
number of task groups. This is the worst case behaviour I can't seem to get out
of, the avg. case of the algorithms can be improved, I focused on correctness
and worst case.

[ akpm@linux-foundation.org: move side-effects out of BUG_ON(). ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:30 +01:00
Peter Zijlstra
fa85ae2418 sched: rt time limit
Very simple time limit on the realtime scheduling classes.
Allow the rq's realtime class to consume sched_rt_ratio of every
sched_rt_period slice. If the class exceeds this quota the fair class
will preempt the realtime class.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:29 +01:00
Peter Zijlstra
8f4d37ec07 sched: high-res preemption tick
Use HR-timers (when available) to deliver an accurate preemption tick.

The regular scheduler tick that runs at 1/HZ can be too coarse when nice
level are used. The fairness system will still keep the cpu utilisation 'fair'
by then delaying the task that got an excessive amount of CPU time but try to
minimize this by delivering preemption points spot-on.

The average frequency of this extra interrupt is sched_latency / nr_latency.
Which need not be higher than 1/HZ, its just that the distribution within the
sched_latency period is important.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:29 +01:00
Herbert Xu
02b67cc3ba sched: do not do cond_resched() when CONFIG_PREEMPT
Why do we even have cond_resched when real preemption
is on? It seems to be a waste of space and time.

remove cond_resched with CONFIG_PREEMPT on.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:28 +01:00
Ingo Molnar
03319ec8b0 sched: documentation, whitespace fixes
whitespace fixes.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:28 +01:00
Peter Zijlstra
fa717060f1 sched: sched_rt_entity
Move the task_struct members specific to rt scheduling together.
A future optimization could be to put sched_entity and sched_rt_entity
into a union.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:27 +01:00
Gregory Haskins
dc938520d2 sched: dynamically update the root-domain span/online maps
The baseline code statically builds the span maps when the domain is formed.
Previous attempts at dynamically updating the maps caused a suspend-to-ram
regression, which should now be fixed.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
CC: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:26 +01:00
Steven Rostedt
cb46984504 sched: RT-balance, add new methods to sched_class
Dmitry Adamushko found that the current implementation of the RT
balancing code left out changes to the sched_setscheduler and
rt_mutex_setprio.

This patch addresses this issue by adding methods to the schedule classes
to handle being switched out of (switched_from) and being switched into
(switched_to) a sched_class. Also a method for changing of priorities
is also added (prio_changed).

This patch also removes some duplicate logic between rt_mutex_setprio and
sched_setscheduler.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:22 +01:00
Steven Rostedt
9a897c5a67 sched: RT-balance, replace hooks with pre/post schedule and wakeup methods
To make the main sched.c code more agnostic to the schedule classes.
Instead of having specific hooks in the schedule code for the RT class
balancing. They are replaced with a pre_schedule, post_schedule
and task_wake_up methods. These methods may be used by any of the classes
but currently, only the sched_rt class implements them.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:22 +01:00
Dmitry Adamushko
5d2f5a616d sched: get rid of 'new_cpu' in try_to_wake_up()
Clean-up try_to_wake_up().

Get rid of the 'new_cpu' variable in try_to_wake_up() [ that's, one
#ifdef section less ].  Also remove a few redundant blank lines.

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:21 +01:00
Ingo Molnar
b913176917 sched: add credits for RT balancing improvements
add credits for RT balancing improvements.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:19 +01:00
Ingo Molnar
0eab914657 sched: style cleanup, #2
style cleanup of various changes that were done recently.

no code changed:

      text    data     bss     dec     hex filename
     26399    2578      48   29025    7161 sched.o.before
     26399    2578      48   29025    7161 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:19 +01:00
Ingo Molnar
d7876a08db sched: remove unused JIFFIES_TO_NS() macro
remove unused JIFFIES_TO_NS() macro.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:19 +01:00
Gregory Haskins
637f50851b sched: only balance our RT tasks within our domain
We move the rt-overload data as the first global to per-domain
reclassification.  This limits the scope of overload related cache-line
bouncing to stay with a specified partition instead of affecting all
cpus in the system.

Finally, we limit the scope of find_lowest_cpu searches to the domain
instead of the entire system.  Note that we would always respect domain
boundaries even without this patch, but we first would scan potentially
all cpus before whittling the list down.  Now we can avoid looking at
RQs that are out of scope, again reducing cache-line hits.

Note: In some cases, task->cpus_allowed will effectively reduce our search
to within our domain.  However, I believe there are cases where the
cpus_allowed mask may be all ones and therefore we err on the side of
caution.  If it can be optimized later, so be it.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
CC: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:18 +01:00
Gregory Haskins
57d885fea0 sched: add sched-domain roots
We add the notion of a root-domain which will be used later to rescope
global variables to per-domain variables.  Each exclusive cpuset
essentially defines an island domain by fully partitioning the member cpus
from any other cpuset.  However, we currently still maintain some
policy/state as global variables which transcend all cpusets.  Consider,
for instance, rt-overload state.

Whenever a new exclusive cpuset is created, we also create a new
root-domain object and move each cpu member to the root-domain's span.
By default the system creates a single root-domain with all cpus as
members (mimicking the global state we have today).

We add some plumbing for storing class specific data in our root-domain.
Whenever a RQ is switching root-domains (because of repartitioning) we
give each sched_class the opportunity to remove any state from its old
domain and add state to the new one.  This logic doesn't have any clients
yet but it will later in the series.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
CC: Christoph Lameter <clameter@sgi.com>
CC: Paul Jackson <pj@sgi.com>
CC: Simon Derr <simon.derr@bull.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:18 +01:00
Steven Rostedt
0d1311a536 sched: RT-balance on new task
rt-balance when creating new tasks.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:14 +01:00
Gregory Haskins
a22d7fc187 sched: wake-balance fixes
We have logic to detect whether the system has migratable tasks, but we are
not using it when deciding whether to push tasks away.  So we add support
for considering this new information.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:12 +01:00
Gregory Haskins
e7693a362e sched: de-SCHED_OTHER-ize the RT path
The current wake-up code path tries to determine if it can optimize the
wake-up to "this_cpu" by computing load calculations.  The problem is that
these calculations are only relevant to SCHED_OTHER tasks where load is king.
For RT tasks, priority is king.  So the load calculation is completely wasted
bandwidth.

Therefore, we create a new sched_class interface to help with
pre-wakeup routing decisions and move the load calculation as a function
of CFS task's class.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:09 +01:00
Gregory Haskins
73fe6aae84 sched: add RT-balance cpu-weight
Some RT tasks (particularly kthreads) are bound to one specific CPU.
It is fairly common for two or more bound tasks to get queued up at the
same time.  Consider, for instance, softirq_timer and softirq_sched.  A
timer goes off in an ISR which schedules softirq_thread to run at RT50.
Then the timer handler determines that it's time to smp-rebalance the
system so it schedules softirq_sched to run.  So we are in a situation
where we have two RT50 tasks queued, and the system will go into
rt-overload condition to request other CPUs for help.

This causes two problems in the current code:

1) If a high-priority bound task and a low-priority unbounded task queue
   up behind the running task, we will fail to ever relocate the unbounded
   task because we terminate the search on the first unmovable task.

2) We spend precious futile cycles in the fast-path trying to pull
   overloaded tasks over.  It is therefore optimial to strive to avoid the
   overhead all together if we can cheaply detect the condition before
   overload even occurs.

This patch tries to achieve this optimization by utilizing the hamming
weight of the task->cpus_allowed mask.  A weight of 1 indicates that
the task cannot be migrated.  We will then utilize this information to
skip non-migratable tasks and to eliminate uncessary rebalance attempts.

We introduce a per-rq variable to count the number of migratable tasks
that are currently running.  We only go into overload if we have more
than one rt task, AND at least one of them is migratable.

In addition, we introduce a per-task variable to cache the cpus_allowed
weight, since the hamming calculation is probably relatively expensive.
We only update the cached value when the mask is updated which should be
relatively infrequent, especially compared to scheduling frequency
in the fast path.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:07 +01:00
Steven Rostedt
4642dafdf9 sched: push RT tasks from overloaded CPUs
This patch adds pushing of overloaded RT tasks from a runqueue that is
having tasks (most likely RT tasks) added to the run queue.

TODO: We don't cover the case of waking of new RT tasks (yet).

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:07 +01:00
Steven Rostedt
f65eda4f78 sched: pull RT tasks from overloaded runqueues
This patch adds the algorithm to pull tasks from RT overloaded runqueues.

When a pull RT is initiated, all overloaded runqueues are examined for
a RT task that is higher in prio than the highest prio task queued on the
target runqueue. If another runqueue holds a RT task that is of higher
prio than the highest prio task on the target runqueue is found it is pulled
to the target runqueue.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:07 +01:00
Steven Rostedt
e8fa136262 sched: add RT task pushing
This patch adds an algorithm to push extra RT tasks off a run queue to
other CPU runqueues.

When more than one RT task is added to a run queue, this algorithm takes
an assertive approach to push the RT tasks that are not running onto other
run queues that have lower priority.  The way this works is that the highest
RT task that is not running is looked at and we examine the runqueues on
the CPUS for that tasks affinity mask. We find the runqueue with the lowest
prio in the CPU affinity of the picked task, and if it is lower in prio than
the picked task, we push the task onto that CPU runqueue.

We continue pushing RT tasks off the current runqueue until we don't push any
more.  The algorithm stops when the next highest RT task can't preempt any
other processes on other CPUS.

TODO: The algorithm may stop when there are still RT tasks that can be
 migrated. Specifically, if the highest non running RT task CPU affinity
 is restricted to CPUs that are running higher priority tasks, there may
 be a lower priority task queued that has an affinity with a CPU that is
 running a lower priority task that it could be migrated to.  This
 patch set does not address this issue.

Note: checkpatch reveals two over 80 character instances. I'm not sure
 that breaking them up will help visually, so I left them as is.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:05 +01:00
Steven Rostedt
764a9d6fe4 sched: track highest prio task queued
This patch adds accounting to each runqueue to keep track of the
highest prio task queued on the run queue. We only care about
RT tasks, so if the run queue does not contain any active RT tasks
its priority will be considered MAX_RT_PRIO.

This information will be used for later patches.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:04 +01:00
Steven Rostedt
63489e45e2 sched: count # of queued RT tasks
This patch adds accounting to keep track of the number of RT tasks running
on a runqueue. This information will be used in later patches.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:03 +01:00
Ingo Molnar
82a1fcb902 softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks
this patch extends the soft-lockup detector to automatically
detect hung TASK_UNINTERRUPTIBLE tasks. Such hung tasks are
printed the following way:

 ------------------>
 INFO: task prctl:3042 blocked for more than 120 seconds.
 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message
 prctl         D fd5e3793     0  3042   2997
        f6050f38 00000046 00000001 fd5e3793 00000009 c06d8264 c06dae80 00000286
        f6050f40 f6050f00 f7d34d90 f7d34fc8 c1e1be80 00000001 f6050000 00000000
        f7e92d00 00000286 f6050f18 c0489d1a f6050f40 00006605 00000000 c0133a5b
 Call Trace:
  [<c04883a5>] schedule_timeout+0x6d/0x8b
  [<c04883d8>] schedule_timeout_uninterruptible+0x15/0x17
  [<c0133a76>] msleep+0x10/0x16
  [<c0138974>] sys_prctl+0x30/0x1e2
  [<c0104c52>] sysenter_past_esp+0x5f/0xa5
  =======================
 2 locks held by prctl/3042:
 #0:  (&sb->s_type->i_mutex_key#5){--..}, at: [<c0197d11>] do_fsync+0x38/0x7a
 #1:  (jbd_handle){--..}, at: [<c01ca3d2>] journal_start+0xc7/0xe9
 <------------------

the current default timeout is 120 seconds. Such messages are printed
up to 10 times per bootup. If the system has crashed already then the
messages are not printed.

if lockdep is enabled then all held locks are printed as well.

this feature is a natural extension to the softlockup-detector (kernel
locked up without scheduling) and to the NMI watchdog (kernel locked up
with IRQs disabled).

[ Gautham R Shenoy <ego@in.ibm.com>: CPU hotplug fixes. ]
[ Andrew Morton <akpm@linux-foundation.org>: build warning fix. ]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2008-01-25 21:08:02 +01:00
Gautham R Shenoy
95402b3829 cpu-hotplug: replace per-subsystem mutexes with get_online_cpus()
This patch converts the known per-subsystem mutexes to get_online_cpus
put_online_cpus. It also eliminates the CPU_LOCK_ACQUIRE and
CPU_LOCK_RELEASE hotplug notification events.

Signed-off-by: Gautham  R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:02 +01:00