android_kernel_sony_msm8994/include
Peter Williams 4301065920 sched: simplify move_tasks()
The move_tasks() function is currently multiplexed with two distinct
capabilities:

1. attempt to move a specified amount of weighted load from one run
queue to another; and
2. attempt to move a specified number of tasks from one run queue to
another.

The first of these capabilities is used in two places, load_balance()
and load_balance_idle(), and in both of these cases the return value of
move_tasks() is used purely to decide if tasks/load were moved and no
notice of the actual number of tasks moved is taken.

The second capability is used in exactly one place,
active_load_balance(), to attempt to move exactly one task and, as
before, the return value is only used as an indicator of success or failure.

This multiplexing of sched_task() was introduced, by me, as part of the
smpnice patches and was motivated by the fact that the alternative, one
function to move specified load and one to move a single task, would
have led to two functions of roughly the same complexity as the old
move_tasks() (or the new balance_tasks()).  However, the new modular
design of the new CFS scheduler allows a simpler solution to be adopted
and this patch addresses that solution by:

1. adding a new function, move_one_task(), to be used by
active_load_balance(); and
2. making move_tasks() a single purpose function that tries to move a
specified weighted load and returns 1 for success and 0 for failure.

One of the consequences of these changes is that neither move_one_task()
or the new move_tasks() care how many tasks sched_class.load_balance()
moves and this enables its interface to be simplified by returning the
amount of load moved as its result and removing the load_moved pointer
from the argument list.  This helps simplify the new move_tasks() and
slightly reduces the amount of work done in each of
sched_class.load_balance()'s implementations.

Further simplification, e.g. changes to balance_tasks(), are possible
but (slightly) complicated by the special needs of load_balance_fair()
so I've left them to a later patch (if this one gets accepted).

NB Since move_tasks() gets called with two run queue locks held even
small reductions in overhead are worthwhile.

[ mingo@elte.hu ]

this change also reduces code size nicely:

   text    data     bss     dec     hex filename
   39216    3618      24   42858    a76a sched.o.before
   39173    3618      24   42815    a73f sched.o.after

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
..
acpi ACPI: restore CONFIG_ACPI_SLEEP 2007-07-29 16:53:59 -07:00
asm-alpha remove unused TIF_NOTIFY_RESUME flag 2007-07-31 15:39:38 -07:00
asm-arm [ARM] 4531/1: remove is_in_rom() protptype 2007-08-04 22:13:43 +01:00
asm-avr32 Fix WARN_ON() on bitfield ops for all other archs 2007-08-01 20:45:38 -07:00
asm-blackfin remove unused TIF_NOTIFY_RESUME flag 2007-07-31 15:39:38 -07:00
asm-cris remove unused TIF_NOTIFY_RESUME flag 2007-07-31 15:39:38 -07:00
asm-frv FRV: Enable the MB86943 PCI arbiter correctly 2007-08-01 20:48:17 -07:00
asm-generic Fix WARN_ON() on bitfield ops 2007-07-31 21:12:07 -07:00
asm-h8300 remove unused TIF_NOTIFY_RESUME flag 2007-07-31 15:39:38 -07:00
asm-i386 revert "x86, serial: convert legacy COM ports to platform devices" 2007-07-31 15:39:38 -07:00
asm-ia64 remove unused TIF_NOTIFY_RESUME flag 2007-07-31 15:39:38 -07:00
asm-m32r remove unused TIF_NOTIFY_RESUME flag 2007-07-31 15:39:38 -07:00
asm-m68k more include order horrors 2007-07-28 19:42:21 -07:00
asm-m68knommu remove unused TIF_NOTIFY_RESUME flag 2007-07-31 15:39:38 -07:00
asm-mips Merge branch 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus 2007-07-31 20:41:53 -07:00
asm-parisc Fix WARN_ON() on bitfield ops for all other archs 2007-08-01 20:45:38 -07:00
asm-powerpc [POWERPC] Fixes for the SLB shadow buffer code 2007-08-03 19:36:01 +10:00
asm-ppc [WATCHDOG] mv64x60_wdt: Add arch/powerpc platform support 2007-07-24 21:16:02 +00:00
asm-s390 Fix WARN_ON() on bitfield ops for all other archs 2007-08-01 20:45:38 -07:00
asm-sh Merge master.kernel.org:/pub/scm/linux/kernel/git/lethal/sh-2.6.23 2007-08-03 15:07:10 -07:00
asm-sh64 sh64: Kill off virt_to_bus()/bus_to_virt(). 2007-07-31 13:11:25 +09:00
asm-sparc [SPARC32]: Fix build. 2007-08-04 21:17:18 -07:00
asm-sparc64 [SPARC]: Fix O_CLOEXEC values. 2007-08-03 14:24:17 -07:00
asm-um arch: personality independent stack top 2007-07-19 10:04:45 -07:00
asm-v850 remove unused TIF_NOTIFY_RESUME flag 2007-07-31 15:39:38 -07:00
asm-x86_64 revert "x86, serial: convert legacy COM ports to platform devices" 2007-07-31 15:39:38 -07:00
asm-xtensa remove unused TIF_NOTIFY_RESUME flag 2007-07-31 15:39:38 -07:00
crypto
keys
linux sched: simplify move_tasks() 2007-08-09 11:16:46 +02:00
math-emu
media V4L/DVB (5835): saa7146/dvb-ttpci: Fix signedness warnings (gcc 4.1.1, kernel 2.6.22) 2007-07-18 14:24:44 -03:00
mtd UBI: kill homegrown endian macros 2007-07-18 16:53:49 +03:00
net Merge davem@master.kernel.org:/pub/scm/linux/kernel/git/vxy/lksctp-dev 2007-08-02 19:44:43 -07:00
pcmcia PCMCIA-NETDEV : add new ID of lan&modem multifunction card 2007-07-08 22:16:39 -04:00
rdma IB/cm: Include HCA ACK delay in local ACK timeout 2007-07-10 21:50:05 -07:00
rxrpc
scsi [SCSI] sd: disentangle barriers in SCSI 2007-08-04 08:37:04 -05:00
sound [ALSA] version 1.0.14 2007-07-20 11:13:35 +02:00
video remove tx3912fb 2007-07-31 15:39:41 -07:00
xen xen: xen/page.h compile fix 2007-07-26 11:35:16 -07:00
Kbuild