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SubjectRe: [PATCH] sched,trace: Allow tracing the preemption decision on wakeup
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On Thu, 2013-03-14 at 10:48 +0100, Peter Zijlstra wrote:
> 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@linutronix.de>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

Acked-by: Steven Rostedt <rostedt@goodmis.org>

> ---
> 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;
> #ifdef CONFIG_SMP
>




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