Tim Chen 333c5ae994 idle governor: Avoid lock acquisition to read pm_qos before entering idle ... Thanks to the reviews and comments by Rafael, James, Mark and Andi. Here's version 2 of the patch incorporating your comments and also some update to my previous patch comments. I noticed that before entering idle state, the menu idle governor will look up the current pm_qos target value according to the list of qos requests received. This look up currently needs the acquisition of a lock to access the list of qos requests to find the qos target value, slowing down the entrance into idle state due to contention by multiple cpus to access this list. The contention is severe when there are a lot of cpus waking and going into idle. For example, for a simple workload that has 32 pair of processes ping ponging messages to each other, where 64 cpu cores are active in test system, I see the following profile with 37.82% of cpu cycles spent in contention of pm_qos_lock: - 37.82% swapper [kernel.kallsyms] [k] _raw_spin_lock_irqsave - _raw_spin_lock_irqsave - 95.65% pm_qos_request menu_select cpuidle_idle_call - cpu_idle 99.98% start_secondary A better approach will be to cache the updated pm_qos target value so reading it does not require lock acquisition as in the patch below. With this patch the contention for pm_qos_lock is removed and I saw a 2.2X increase in throughput for my message passing workload. cc: stable@kernel.org Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Acked-by: Andi Kleen <ak@linux.intel.com> Acked-by: James Bottomley <James.Bottomley@suse.de> Acked-by: mark gross <markgross@thegnar.org> Signed-off-by: Len Brown <len.brown@intel.com>		2011-05-29 00:50:59 -04:00
..
debug	Merge branch 'master' into for-next	2010-12-22 18:57:02 +01:00
gcov
irq	genirq: Disable the SHIRQ_DEBUG call in request_threaded_irq for now	2011-02-19 12:11:13 +01:00
power	Merge branch 'fixes-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq	2011-02-18 12:36:06 -08:00
time	clockevents: Prevent oneshot mode when broadcast device is periodic	2011-02-26 09:45:28 +01:00
trace	blktrace: Remove blk_fill_rwbs_rq.	2011-03-03 10:53:20 -05:00
.gitignore
acct.c
async.c
audit_tree.c
audit_watch.c
audit.c
audit.h
auditfilter.c
auditsc.c
backtracetest.c
bounds.c
capability.c	security: add cred argument to security_capable()	2011-02-11 17:41:58 +11:00
cgroup_freezer.c
cgroup.c	Merge branch 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin	2011-01-14 09:08:29 -08:00
compat.c
configs.c
cpu.c	Merge branches 'x86-alternatives-for-linus', 'x86-fpu-for-linus', 'x86-hwmon-for-linus', 'x86-paravirt-for-linus', 'core-locking-for-linus' and 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2011-01-06 11:11:50 -08:00
cpuset.c	cpuset: add a missing unlock in cpuset_write_resmask()	2011-03-04 17:53:38 -08:00
cred.c	CRED: Fix memory and refcount leaks upon security_prepare_creds() failure	2011-02-07 14:04:00 -08:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c	Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2011-01-11 11:02:13 -08:00
extable.c
fork.c	thp: khugepaged	2011-01-13 17:32:43 -08:00
freezer.c	Freezer: Fix a race during freezing of TASK_STOPPED tasks	2010-12-24 15:02:40 +01:00
futex_compat.c
futex.c	Merge branches 'core-fixes-for-linus', 'x86-fixes-for-linus', 'timers-fixes-for-linus' and 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2011-01-15 12:45:00 -08:00
groups.c
hrtimer.c	Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2011-01-13 10:05:56 -08:00
hung_task.c
hw_breakpoint.c	perf: Dynamic pmu types	2010-12-16 11:36:43 +01:00
irq_work.c	irq_work: Use per cpu atomics instead of regular atomics	2010-12-18 15:54:48 +01:00
itimer.c
jump_label.c
kallsyms.c	Revert "kernel: make /proc/kallsyms mode 400 to reduce ease of attacking"	2010-11-19 11:54:40 -08:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c
kfifo.c
kmod.c
kprobes.c	Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu	2011-01-07 17:02:58 -08:00
ksysfs.c
kthread.c	sched: Constify function scope static struct sched_param usage	2011-01-07 15:55:45 +01:00
latencytop.c	fs/proc/base.c, kernel/latencytop.c: convert sprintf_symbol() to %ps	2011-01-13 08:03:16 -08:00
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
lockdep.c	lockdep: Move early boot local IRQ enable/disable status to init/main.c	2011-01-20 13:32:33 +01:00
Makefile	kernel: clean up USE_GENERIC_SMP_HELPERS	2011-01-13 08:03:08 -08:00
module.c	tracepoints: Fix section alignment using pointer array	2011-02-03 09:28:46 -05:00
mutex-debug.c
mutex-debug.h
mutex.c	mutexes, sched: Introduce arch_mutex_cpu_relax()	2010-11-26 15:05:34 +01:00
mutex.h
notifier.c
ns_cgroup.c
nsproxy.c
padata.c
panic.c	ACPI, APEI, Generic Hardware Error Source POLL/IRQ/NMI notification type support	2011-01-12 03:06:19 -05:00
params.c	module: show version information for built-in modules in sysfs	2011-01-24 14:32:51 +10:30
perf_event.c	perf: Fix throttle logic	2011-02-16 13:25:29 +01:00
pid_namespace.c
pid.c
pm_qos_params.c	idle governor: Avoid lock acquisition to read pm_qos before entering idle	2011-05-29 00:50:59 -04:00
posix-cpu-timers.c
posix-timers.c
printk.c	cap_syslog: accept CAP_SYS_ADMIN for now	2011-02-10 17:53:55 -08:00
profile.c
ptrace.c	Mark ptrace_{traceme,attach,detach} static	2011-03-04 09:23:30 -08:00
range.c	kernel/range.c: fix clean_sort_range() for the case of full array	2010-11-12 07:55:31 -08:00
rcupdate.c
rcutiny_plugin.h	rcu: Distinguish between boosting and boosted	2010-11-29 22:01:56 -08:00
rcutiny.c	rcu: avoid pointless blocked-task warnings	2011-01-14 04:58:08 -08:00
rcutorture.c
rcutree_plugin.h	rcu: increase synchronize_sched_expedited() batching	2010-12-17 12:34:08 -08:00
rcutree_trace.c	rcu,cleanup: simplify the code when cpu is dying	2010-11-29 22:01:58 -08:00
rcutree.c	Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu	2011-01-07 17:02:58 -08:00
rcutree.h	rcu: limit rcu_node leaf-level fanout	2010-12-17 12:34:20 -08:00
relay.c
res_counter.c
resource.c	resources: add arch hook for preventing allocation in reserved areas	2010-12-17 10:01:09 -08:00
rtmutex_common.h
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c
rtmutex.h
rwsem.c
sched_autogroup.c	sched, autogroup: Fix CONFIG_RT_GROUP_SCHED sched_setscheduler() failure	2011-01-18 15:09:42 +01:00
sched_autogroup.h	sched, autogroup: Fix CONFIG_RT_GROUP_SCHED sched_setscheduler() failure	2011-01-18 15:09:42 +01:00
sched_clock.c	sched: Add some clock info to sched_debug	2010-11-23 10:29:08 +01:00
sched_cpupri.c
sched_cpupri.h
sched_debug.c	sched: Replace rq->bkl_count with rq->rq_sched_info.bkl_count	2011-01-18 15:09:43 +01:00
sched_fair.c	sched: Use rq->clock_task instead of rq->clock for correctly maintaining load averages	2011-01-26 12:31:03 +01:00
sched_features.h	sched: Rewrite tg_shares_up)	2010-11-18 13:27:46 +01:00
sched_idletask.c
sched_rt.c	sched: Fix sched rt group scheduling when hierachy is enabled	2011-03-04 11:03:18 +01:00
sched_stats.h
sched_stoptask.c	sched: Fix cross-sched-class wakeup preemption	2010-11-11 14:37:23 +01:00
sched.c	SUNRPC: Close a race in __rpc_wait_for_completion_task()	2011-03-10 15:04:52 -05:00
seccomp.c
semaphore.c
signal.c
smp.c	Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2011-01-20 18:30:37 -08:00
softirq.c	kernel: clean up USE_GENERIC_SMP_HELPERS	2011-01-13 08:03:08 -08:00
spinlock.c
srcu.c	rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status	2011-01-14 04:56:49 -08:00
stacktrace.c
stop_machine.c
sys_ni.c
sys.c	Fix prlimit64 for suid/sgid processes	2011-01-31 13:01:27 +10:00
sysctl_binary.c	Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2011-01-13 10:05:56 -08:00
sysctl_check.c
sysctl.c	unfuck proc_sysctl ->d_compare()	2011-03-08 02:22:27 -05:00
taskstats.c	taskstats: use better ifdef for alignment	2011-01-13 08:03:19 -08:00
test_kprobes.c
time.c	Kill off a bunch of warning: ‘inline’ is not at beginning of declaration	2010-11-28 23:08:04 +01:00
timeconst.pl
timer.c	Revert "lockdep, timer: Fix del_timer_sync() annotation"	2011-02-08 16:18:39 +01:00
tracepoint.c	tracepoints: Fix section alignment using pointer array	2011-02-03 09:28:46 -05:00
tsacct.c
uid16.c
up.c
user_namespace.c	user_ns: improve the user_ns on-the-slab packaging	2011-01-13 08:03:18 -08:00
user-return-notifier.c
user.c	fix freeing user_struct in user cache	2010-12-29 11:31:38 -08:00
utsname_sysctl.c
utsname.c
wait.c
watchdog.c	watchdog, nmi: Lower the severity of error messages	2011-02-10 13:21:59 +01:00
workqueue_sched.h
workqueue.c	workqueue: make sure MAYDAY_INITIAL_TIMEOUT is at least 2 jiffies long	2011-02-16 18:10:19 +01:00