Stephane Eranian
a8d757ef07
perf events: Fix slow and broken cgroup context switch code ...
The current cgroup context switch code was incorrect leading
to bogus counts. Furthermore, as soon as there was an active
cgroup event on a CPU, the context switch cost on that CPU
would increase by a significant amount as demonstrated by a
simple ping/pong example:
$ ./pong
Both processes pinned to CPU1, running for 10s
10684.51 ctxsw/s
Now start a cgroup perf stat:
$ perf stat -e cycles,cycles -A -a -G test -C 1 -- sleep 100
$ ./pong
Both processes pinned to CPU1, running for 10s
6674.61 ctxsw/s
That's a 37% penalty.
Note that pong is not even in the monitored cgroup.
The results shown by perf stat are bogus:
$ perf stat -e cycles,cycles -A -a -G test -C 1 -- sleep 100
Performance counter stats for 'sleep 100':
CPU1 <not counted> cycles test
CPU1 16,984,189,138 cycles # 0.000 GHz
The second 'cycles' event should report a count @ CPU clock
(here 2.4GHz) as it is counting across all cgroups.
The patch below fixes the bogus accounting and bypasses any
cgroup switches in case the outgoing and incoming tasks are
in the same cgroup.
With this patch the same test now yields:
$ ./pong
Both processes pinned to CPU1, running for 10s
10775.30 ctxsw/s
Start perf stat with cgroup:
$ perf stat -e cycles,cycles -A -a -G test -C 1 -- sleep 10
Run pong outside the cgroup:
$ /pong
Both processes pinned to CPU1, running for 10s
10687.80 ctxsw/s
The penalty is now less than 2%.
And the results for perf stat are correct:
$ perf stat -e cycles,cycles -A -a -G test -C 1 -- sleep 10
Performance counter stats for 'sleep 10':
CPU1 <not counted> cycles test # 0.000 GHz
CPU1 23,933,981,448 cycles # 0.000 GHz
Now perf stat reports the correct counts for
for the non cgroup event.
If we run pong inside the cgroup, then we also get the
correct counts:
$ perf stat -e cycles,cycles -A -a -G test -C 1 -- sleep 10
Performance counter stats for 'sleep 10':
CPU1 22,297,726,205 cycles test # 0.000 GHz
CPU1 23,933,981,448 cycles # 0.000 GHz
10.001457237 seconds time elapsed
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110825135803.GA4697@quad
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-29 12:28:33 +02:00
Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb
2011-08-01 13:39:40 -10:00
perf events: Fix slow and broken cgroup context switch code
2011-08-29 12:28:33 +02:00
gcov: disable CONSTRUCTORS for UML
2011-07-26 16:49:45 -07:00
Revert "irq: Always set IRQF_ONESHOT if no primary handler is specified"
2011-08-23 10:36:51 -07:00
PM / Domains: Fix build for CONFIG_PM_RUNTIME unset
2011-08-14 13:34:31 +02:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-07-22 16:52:18 -07:00
Merge branch 'for-linus' of git://git.kernel.dk/linux-block
2011-08-19 10:47:07 -07:00
async: Fixed an include coding style issue
2011-06-14 22:48:46 -04:00
atomic: use <linux/atomic.h>
2011-07-26 16:49:47 -07:00
audit_tree,rcu: Convert call_rcu(__put_tree) to kfree_rcu()
2011-07-20 14:10:11 -07:00
kill path_lookup()
2011-03-14 09:15:23 -04:00
netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms
2011-03-03 10:55:40 -08:00
atomic: use <linux/atomic.h>
2011-07-26 16:49:47 -07:00
memcg: remove direct page_cgroup-to-page pointer
2011-03-23 19:46:28 -07:00
Merge branch 'master' into next
2011-05-19 18:51:57 +10:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6
2011-07-27 19:26:38 -07:00
cgroups: add per-thread subsystem callbacks
2011-05-26 17:12:34 -07:00
Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6
2011-07-30 00:08:53 -07:00
kernel/configs.c: include MODULE_*() when CONFIG_IKCONFIG_PROC=n
2011-07-25 20:57:15 -07:00
Fix common misspellings
2011-03-31 11:26:23 -03:00
atomic: use <linux/atomic.h>
2011-07-26 16:49:47 -07:00
crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn
2011-03-23 19:47:19 -07:00
move RLIMIT_NPROC check from set_user() to do_execve_common()
2011-08-11 11:24:42 -07:00
KVM: Steal time implementation
2011-07-14 12:59:14 +03:00
ipc: introduce shm_rmid_forced sysctl
2011-07-26 16:49:44 -07:00
extable, core_kernel_data(): Make sure all archs define _sdata
2011-05-20 08:56:56 +02:00
move RLIMIT_NPROC check from set_user() to do_execve_common()
2011-08-11 11:24:42 -07:00
Freezer: Use SMP barriers
2011-05-17 23:19:17 +02:00
Merge branch 'linus' into core/urgent
2011-08-04 09:09:27 +02:00
userns: user namespaces: convert several capable() calls
2011-03-23 19:47:08 -07:00
userns: user namespaces: convert several capable() calls
2011-03-23 19:47:08 -07:00
hrtimers: Fix typo causing erratic timers
2011-05-25 15:31:58 -07:00
watchdog, hung_task_timeout: Add Kconfig configurable default
2011-04-28 09:13:17 +02:00
irq_work: Use per cpu atomics instead of regular atomics
2010-12-18 15:54:48 +01:00
jump_label: Fix jump_label update for modules
2011-06-29 09:59:17 -04:00
Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-03-25 17:52:22 -07:00
arch:Kconfig.locks Remove unused config option.
2011-04-10 17:01:05 +02:00
sched: Isolate preempt counting in its own config option
2011-06-10 15:15:40 +02:00
treewide: Convert uses of struct resource to resource_size(ptr)
2011-06-10 14:55:36 +02:00
Boot up with usermodehelper disabled
2011-08-03 22:03:29 -10:00
kprobes: Return -ENOENT if probe point doesn't exist
2011-07-15 15:11:47 -04:00
kernel/ksysfs.c: expose file_caps_enabled in sysfs
2011-04-19 16:45:51 -07:00
cpuset: Fix cpuset_cpus_allowed_fallback(), don't update tsk->rt.nr_cpus_allowed
2011-05-28 17:02:57 +02:00
Fix common misspellings
2011-03-31 11:26:23 -03:00
lockdep: Fix wrong assumption in match_held_lock
2011-08-09 11:57:35 +02:00
lockdep: Remove unused 'factor' variable from lockdep_stats_show()
2011-03-23 13:54:47 +01:00
jump label: Reduce the cycle count by changing the link order
2011-08-05 23:57:33 +02:00
module: add /sys/module/<name>/uevent files
2011-07-24 22:06:04 +09:30
mutex: Use p->on_cpu for the adaptive spin
2011-04-14 08:52:33 +02:00
mutex: Use p->on_cpu for the adaptive spin
2011-04-14 08:52:33 +02:00
lockdep, mutex: provide mutex_lock_nest_lock
2011-05-25 08:39:17 -07:00
mutex: Use p->on_cpu for the adaptive spin
2011-04-14 08:52:33 +02:00
notifiers: sys: move reboot notifiers into reboot.h
2011-07-25 20:57:14 -07:00
make sure that nsproxy_cache is initialized early enough
2011-07-20 01:44:07 -04:00
Fix common misspellings
2011-03-31 11:26:23 -03:00
panic: panic=-1 for immediate reboot
2011-07-26 16:49:45 -07:00
module: add /sys/module/<name>/uevent files
2011-07-24 22:06:04 +09:30
rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_check
2011-07-08 22:21:58 +02:00
pidns: call pid_ns_prepare_proc() from create_pid_namespace()
2011-03-23 19:46:58 -07:00
plist: Remove the need to supply locks to plist heads
2011-07-08 14:02:53 +02:00
hrtimers: Avoid touching inactive timer bases
2011-05-23 13:59:54 +02:00
posix-timers: RCU conversion
2011-05-24 12:10:51 +02:00
kernel/printk: do not turn off bootconsole in printk_late_init() if keep_bootcon
2011-08-25 16:25:34 -07:00
kernel/profile.c: remove some duplicate code from profile_hits()
2011-05-26 17:12:37 -07:00
connector: add an event for monitoring process tracers
2011-07-18 21:38:33 +02:00
atomic: use <linux/atomic.h>
2011-07-26 16:49:47 -07:00
sanitize <linux/prefetch.h> usage
2011-05-20 12:50:29 -07:00
rcu: Converge TINY_RCU expedited and normal boosting
2011-05-05 23:16:58 -07:00
atomic: use <linux/atomic.h>
2011-07-26 16:49:47 -07:00
rcu: Prevent RCU callbacks from executing before scheduler initialized
2011-07-13 08:17:56 -07:00
rcu: Move RCU_BOOST #ifdefs to header file
2011-06-16 16:12:05 -07:00
softirq,rcu: Inform RCU of irq_exit() activity
2011-07-20 10:50:12 -07:00
atomic: use <linux/atomic.h>
2011-07-26 16:49:47 -07:00
memcg: res_counter_read_u64(): fix potential races on 32-bit machines
2011-03-23 19:46:22 -07:00
resources: Add lookup_resource()
2011-07-30 21:21:39 +02:00
rtmutex: Simplify PI algorithm and make highest prio task get lock
2011-01-27 21:13:51 -05:00
rtmutex: tester: Remove the remaining BKL leftovers
2011-02-22 22:07:22 +01:00
plist: Remove the need to supply locks to plist heads
2011-07-08 14:02:53 +02:00
rtmutex: Simplify PI algorithm and make highest prio task get lock
2011-01-27 21:13:51 -05:00
atomic: use <linux/atomic.h>
2011-07-26 16:49:47 -07:00
perf events: Fix slow and broken cgroup context switch code
2011-08-29 12:28:33 +02:00
Fix common misspellings
2011-03-31 11:26:23 -03:00
sched: Skip autogroup when looking for all rt sched groups
2011-07-01 10:39:08 +02:00
sched: Add some clock info to sched_debug
2010-11-23 10:29:08 +01:00
sched: Get rid of lock_depth
2011-04-24 13:18:38 +02:00
sched: Cleanup duplicate local variable in [enqueue|dequeue]_task_fair
2011-07-22 12:47:22 +02:00
Merge branch 'kvm-updates/3.1' of git://git.kernel.org/pub/scm/virt/kvm/kvm
2011-07-24 09:07:03 -07:00
sched: Drop the rq argument to sched_class::select_task_rq()
2011-04-14 08:52:36 +02:00
sched: Skip autogroup when looking for all rt sched groups
2011-07-01 10:39:08 +02:00
sched: More sched_domain iterations fixes
2011-05-28 17:02:54 +02:00
sched: Drop the rq argument to sched_class::select_task_rq()
2011-04-14 08:52:36 +02:00
signals: sys_ssetmask/sys_rt_sigsuspend should use set_current_blocked()
2011-07-27 12:53:36 -07:00
generic-ipi: Fix kexec boot crash by initializing call_single_queue before enabling interrupts
2011-06-17 10:17:12 +02:00
softirq,rcu: Inform RCU of irq_exit() activity
2011-07-20 10:50:12 -07:00
rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status
2011-01-14 04:56:49 -08:00
stack_trace: Add weak save_stack_trace_regs()
2011-06-14 22:48:52 -04:00
atomic: use <linux/atomic.h>
2011-07-26 16:49:47 -07:00
Add a personality to report 2.6.x version numbers
2011-08-25 10:17:28 -07:00
All Arch: remove linkage for sys_nfsservctl system call
2011-08-26 15:09:58 -07:00
sysctl,rcu: Convert call_rcu(free_head) to kfree
2011-07-20 14:10:18 -07:00
xfs: remove subdirectories
2011-08-12 16:21:35 -05:00
xfs: remove subdirectories
2011-08-12 16:21:35 -05:00
taskstats: add_del_listener() should ignore !valid listeners
2011-08-03 14:25:20 -10:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-03-15 18:53:35 -07:00
timers: Consider slack value in mod_timer()
2011-06-03 15:02:32 +02:00
jump label: Introduce static_branch() interface
2011-04-04 12:48:08 -04:00
userns: user namespaces: convert several capable() calls
2011-03-23 19:47:08 -07:00
Fix common misspellings
2011-03-31 11:26:23 -03:00
userns: add a user_namespace as creator/owner of uts_namespace
2011-03-23 19:46:59 -07:00
user_ns: improve the user_ns on-the-slab packaging
2011-01-13 08:03:18 -08:00
ns proc: Add support for the uts namespace
2011-05-10 14:35:35 -07:00
Fix common misspellings
2011-03-31 11:26:23 -03:00
perf, x86: P4 PMU - Introduce event alias feature
2011-07-14 17:25:04 -04:00
Merge branch 'for-3.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
2011-07-22 15:07:15 -07:00
a8d757ef07