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	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
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	pass a struct path to vfs_statfs	2010-08-09 16:48:42 -04:00
async.c	async: use workqueue for worker pool	2010-07-14 11:29:46 +02:00
audit_tree.c	in untag_chunk() we need to do alloc_chunk() a bit earlier	2010-10-30 02:18:32 -04:00
audit_watch.c	audit: make functions static	2010-10-30 01:42:19 -04:00
audit.c	audit: error message typo correction	2010-11-03 13:49:58 -04:00
audit.h	audit: make functions static	2010-10-30 01:42:19 -04:00
auditfilter.c	Audit: add support to match lsm labels on user audit messages	2010-10-30 01:41:57 -04:00
auditsc.c	audit mmap	2010-10-30 08:45:43 -04:00
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_freezer: update_freezer_state() does incorrect state transitions	2010-10-27 18:03:08 -07:00
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	compat: Make compat_alloc_user_space() incorporate the access_ok()	2010-09-14 16:08:45 -07:00
configs.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
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	sys_personality: remove the bogus checks in sys_personality()->__set_personality() path	2010-08-09 20:45:05 -07:00
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: Address compiler warnings in exit_robust_list	2010-11-10 13:27:50 +01:00
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	kernel/groups.c: fix integer overflow in groups_search	2010-09-09 18:57:24 -07:00
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	lockup detector: Fix grammar by adding a missing "to" in the comments	2010-08-17 09:11:52 +02:00
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	jump label: Make arch_jump_label_text_poke_early() optional	2010-10-29 12:56:13 -04:00
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	tree-wide: fix comment/printk typos	2010-11-01 15:38:34 -04:00
kfifo.c	kfifo: fix scatterlist usage	2010-10-01 10:50:58 -07:00
kmod.c	Make do_execve() take a const filename pointer	2010-08-17 18:07:43 -07:00
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	sysfs: add struct file* to bin_attr callbacks	2010-05-21 09:37:31 -07:00
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: No need to disable preemption in debug atomic ops	2010-05-04 05:38:16 +02:00
lockdep_proc.c	locking, lockdep: Convert sprintf_symbol to %pS	2010-11-10 10:23:58 +01:00
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	cgroup: notify ns_cgroup deprecated	2010-10-27 18:03:09 -07:00
nsproxy.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
padata.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6	2010-08-04 15:23:14 -07:00
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	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
pid.c	Add RCU check for find_task_by_vpid().	2010-08-19 17:18:02 -07:00
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-cpu-timers: Rcu_read_lock/unlock protect find_task_by_vpid call	2010-11-10 13:07:06 +01:00
posix-timers.c	posix-timers: Annotate lock_timer()	2010-10-21 17:30:06 +02:00
printk.c	cap_syslog: accept CAP_SYS_ADMIN for now	2011-02-10 17:53:55 -08:00
profile.c	llseek: automatically add .llseek fop	2010-10-15 15:53:27 +02:00
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	Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/rcu	2010-10-07 09:43:11 +02:00
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	rcu: add priority-inversion testing to rcutorture	2010-10-07 10:41:08 -07:00
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	Clean up relay_alloc_page_array() slightly by using vzalloc rather than vmalloc and memset	2010-11-05 08:21:34 -07:00
res_counter.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
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-tester: make it build without BKL	2010-10-19 11:29:56 +02:00
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: No need for bootmem special cases	2010-07-17 12:06:22 +02:00
sched_cpupri.h	sched: No need for bootmem special cases	2010-07-17 12:06:22 +02:00
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: Cure load average vs NO_HZ woes	2010-04-23 11:02:02 +02:00
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_stat: Update sched_info_queue/dequeue() code comments	2010-10-24 13:29:01 +02:00
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	signals: annotate lock context change on ptrace_stop()	2010-10-27 18:03:12 -07:00
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	stop_machine: convert cpu notifier to return encapsulate errno value	2010-10-26 16:52:15 -07:00
sys_ni.c	powerpc: define a compat_sys_recv cond_syscall	2010-09-23 17:03:55 +10:00
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: min/max bounds are optional	2010-10-15 14:42:24 -07:00
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	kprobes: Fix selftest to clear flags field for reusing probes	2010-10-14 08:55:27 +02:00
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	taskstats: use real microsecond granularity for CPU times	2010-10-27 18:03:17 -07:00
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	docbook: add more wait/wake/completion to device-drivers docbook	2010-10-26 17:32:41 -07:00
watchdog.c	watchdog, nmi: Lower the severity of error messages	2011-02-10 13:21:59 +01:00
workqueue_sched.h	workqueue: implement concurrency managed dynamic worker pool	2010-06-29 10:07:14 +02:00
workqueue.c	workqueue: make sure MAYDAY_INITIAL_TIMEOUT is at least 2 jiffies long	2011-02-16 18:10:19 +01:00