[tip:sched/core] sched/tracing: Allow tracing the preemption decision on wakeup

From: tip-bot for Peter Zijlstra
Date: Mon Mar 18 2013 - 07:10:51 EST

Commit-ID: a8d7ad52a7befbde896276d05c75c90fed48b5bf
Gitweb: http://git.kernel.org/tip/a8d7ad52a7befbde896276d05c75c90fed48b5bf
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Thu, 14 Mar 2013 10:48:39 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 18 Mar 2013 10:18:08 +0100

sched/tracing: Allow tracing the preemption decision on wakeup

Thomas noted that we do the wakeup preemption check after the
wakeup trace point, this means the tracepoint cannot test/report
this decision; which is rather important for latency sensitive
workloads. Therefore move the tracepoint after doing the
preemption check.

Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Acked-by: Paul Turner <pjt@xxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Link: http://lkml.kernel.org/r/1363254519.26965.9.camel@laptop
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b36635e..849deb9 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1288,8 +1288,8 @@ static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
static void
ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
- trace_sched_wakeup(p, true);
check_preempt_curr(rq, p, wake_flags);
+ trace_sched_wakeup(p, true);

p->state = TASK_RUNNING;
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