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Subject[tip:perf/core] sched: Deliver sched_switch events to the current task
Commit-ID:  895dd92c032e1604aa0d7afaef7716e058343b67
Gitweb: http://git.kernel.org/tip/895dd92c032e1604aa0d7afaef7716e058343b67
Author: Andrew Vagin <avagin@openvz.org>
AuthorDate: Thu, 12 Jul 2012 14:14:29 +0400
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 26 Jul 2012 12:23:10 +0200

sched: Deliver sched_switch events to the current task

Otherwise they can't be filtered for a defined task:

perf record -e sched:sched_switch ./foo

This command doesn't report any events without this patch.

I think it isn't a security concern if someone knows who will
be executed next - this can already be observed by polling /proc
state. By default perf is disabled for non-root users in any case.

I need these events for profiling sleep times. sched_switch is used for
getting callchains and sched_stat_* is used for getting time periods.
These events are combined in user space, then it can be analyzed by
perf tools.

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arun Sharma <asharma@fb.com>
Link: http://lkml.kernel.org/r/1342088069-1005148-1-git-send-email-avagin@openvz.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/core.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 468bdd4..ad732b5 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1910,12 +1910,12 @@ static inline void
prepare_task_switch(struct rq *rq, struct task_struct *prev,
struct task_struct *next)
{
+ trace_sched_switch(prev, next);
sched_info_switch(prev, next);
perf_event_task_sched_out(prev, next);
fire_sched_out_preempt_notifiers(prev, next);
prepare_lock_switch(rq, next);
prepare_arch_switch(next);
- trace_sched_switch(prev, next);
}

/**

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