* Re: measuring system wide CPU usage ignoring idle process
[not found] ` <20171123151536.3vzjtbs5e4pccxpw@hirez.programming.kicks-ass.net>
@ 2018-04-17 13:41 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; only message in thread
From: Arnaldo Carvalho de Melo @ 2018-04-17 13:41 UTC (permalink / raw)
To: Stephane Eranian
Cc: Peter Zijlstra, Jiri Olsa, Milian Wolff, linux-perf-users,
Namhyung Kim, Ingo Molnar, Alexander Shishkin,
Linux Kernel Mailing List
Em Thu, Nov 23, 2017 at 04:15:36PM +0100, Peter Zijlstra escreveu:
> On Thu, Nov 23, 2017 at 11:42:20AM -0300, Arnaldo Carvalho de Melo wrote:
> > What is wrong with perf_event_attr.exclude_idle? :-)
>
> Neither task- nor cpu-clock actually implement that..
>
> Something like the _completely_untested_ below might cure that for
> cpu-clock. I have the nagging feeling we actually already account the
> idle time _somewhere_, but I couldn't remember and was too lazy to go
> find -- but someone should if this were to become an actual patch.
>
Stephane, this was the thread,
- Arnaldo
> ---
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index a59fe11558a4..5386d551b373 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -8900,6 +8908,10 @@ static void cpu_clock_event_update(struct perf_event *event)
> u64 now;
>
> now = local_clock();
> +
> + if (event->attr.exclude_idle)
> + now -= idle_task(event->oncpu)->se.sum_exec_runtime;
> +
> prev = local64_xchg(&event->hw.prev_count, now);
> local64_add(now - prev, &event->count);
> }
> diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c
> index d518664cce4f..419c620510c6 100644
> --- a/kernel/sched/idle_task.c
> +++ b/kernel/sched/idle_task.c
> @@ -27,9 +27,14 @@ static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int fl
> static struct task_struct *
> pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
> {
> + struct task_struct *idle = rq->idle;
> +
> put_prev_task(rq, prev);
> update_idle_core(rq);
> schedstat_inc(rq->sched_goidle);
> +
> + idle->se.exec_start = rq_clock_task(rq);
> +
> return rq->idle;
> }
>
> @@ -48,6 +53,17 @@ dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)
>
> static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
> {
> + struct task_struct *idle = rq->idle;
> + u64 delta, now;
> +
> + now = rq_clock_task(rq);
> + delta = now - idle->se.exec_start;
> + if (unlikely((s64)delta < 0))
> + delta = 0;
> +
> + idle->se.sum_exec_runtime += delta;
> + idle->se.exec_start = now;
> +
> rq_last_tick_reset(rq);
> }
>
> @@ -57,6 +73,9 @@ static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
>
> static void set_curr_task_idle(struct rq *rq)
> {
> + struct task_struct *idle = rq->idle;
> +
> + idle->se.exec_start = rq_clock_task(rq);
> }
>
> static void switched_to_idle(struct rq *rq, struct task_struct *p)
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