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Date:   Wed, 22 May 2019 16:31:50 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Viktor Rosendahl <viktor.rosendahl@gmail.com>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        Joel Fernandes <joel@joelfernandes.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [PATCH v4 1/4] ftrace: Implement fs notification for
 tracing_max_latency
Message-ID: <20190522143150.GF16275@worktop.programming.kicks-ass.net>
References: <20190517203430.6729-1-viktor.rosendahl@gmail.com>
 <20190517203430.6729-2-viktor.rosendahl@gmail.com>
 <20190521120142.186487e9@gandalf.local.home>
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On Tue, May 21, 2019 at 12:01:42PM -0400, Steven Rostedt wrote:
> 
> [ Added Peter and Rafael ]

Thanks Steve,

> On Fri, 17 May 2019 22:34:27 +0200
> Viktor Rosendahl <viktor.rosendahl@gmail.com> wrote:

> > diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
> > index c8c7c7efb487..a1a1befea1c1 100644
> > --- a/include/trace/events/sched.h
> > +++ b/include/trace/events/sched.h
> > @@ -183,6 +183,46 @@ TRACE_EVENT(sched_switch,
> >  		__entry->next_comm, __entry->next_pid, __entry->next_prio)
> >  );
> >  
> > +/*
> > + * Tracepoint for entering __schedule():
> > + */
> > +TRACE_EVENT(sched_schedule_enter,
> > +
> > +	TP_PROTO(int cpu),
> > +
> > +	TP_ARGS(cpu),
> > +
> > +	TP_STRUCT__entry(
> > +		__field(int, cpu)
> > +	),
> > +
> > +	TP_fast_assign(
> > +		__entry->cpu = cpu;
> > +	),
> > +
> > +	TP_printk("cpu=%d", __entry->cpu)
> > +);
> > +
> > +/*
> > + * Tracepoint for exiting __schedule():
> > + */
> > +TRACE_EVENT(sched_schedule_exit,
> > +
> > +	TP_PROTO(int cpu),
> > +
> > +	TP_ARGS(cpu),
> > +
> > +	TP_STRUCT__entry(
> > +		__field(int, cpu)
> > +	),
> > +
> > +	TP_fast_assign(
> > +		__entry->cpu = cpu;
> > +	),
> > +
> > +	TP_printk("cpu=%d", __entry->cpu)
> > +);
> > +
> >  /*
> >   * Tracepoint for a task being migrated:
> >   */
> > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > index 102dfcf0a29a..c9d86fcc48f5 100644
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -3374,6 +3374,7 @@ static void __sched notrace __schedule(bool preempt)
> >  	int cpu;
> >  
> >  	cpu = smp_processor_id();
> > +	trace_sched_schedule_enter(cpu);
> >  	rq = cpu_rq(cpu);
> >  	prev = rq->curr;
> >  
> > @@ -3448,6 +3449,7 @@ static void __sched notrace __schedule(bool preempt)
> >  	}
> >  
> >  	balance_callback(rq);
> > +	trace_sched_schedule_exit(cpu);
> >  }
> >  
> >  void __noreturn do_task_dead(void)
> > diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
> > index f5516bae0c1b..e328e045c6e8 100644
> > --- a/kernel/sched/idle.c
> > +++ b/kernel/sched/idle.c
> > @@ -224,6 +224,7 @@ static void cpuidle_idle_call(void)
> >  static void do_idle(void)
> >  {
> >  	int cpu = smp_processor_id();
> > +	trace_do_idle_enter(cpu);
> >  	/*
> >  	 * If the arch has a polling bit, we maintain an invariant:
> >  	 *
> > @@ -287,6 +288,7 @@ static void do_idle(void)
> >  
> >  	if (unlikely(klp_patch_pending(current)))
> >  		klp_update_patch_state(current);
> > +	trace_do_idle_exit(cpu);
> >  }
> >  
> >  bool cpu_in_idle(unsigned long pc)

NAK!