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Commit dfc68f29 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
Browse files

sched, trace: Add a tracepoint for IPI-less remote wakeups 



Remote wakeups of polling CPUs are a valuable performance
improvement; add a tracepoint to make it much easier to verify that
they're working.

Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: nicolas.pitre@linaro.org
Cc: daniel.lezcano@linaro.org
Cc: umgwanakikbuti@gmail.com
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/16205aee116772aa686814f9b13bccb562108047.1401902905.git.luto@amacapital.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 84c40708

include/trace/events/sched.h

+20 −0
Original line number Diff line number Diff line
@@ -530,6 +530,26 @@ TRACE_EVENT(sched_swap_numa, 
			__entry->dst_pid, __entry->dst_tgid, __entry->dst_ngid,

			__entry->dst_cpu, __entry->dst_nid)

);



/*

 * Tracepoint for waking a polling cpu without an IPI.

 */

TRACE_EVENT(sched_wake_idle_without_ipi,



	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)

);

#endif /* _TRACE_SCHED_H */



/* This part must be outside protection */

kernel/sched/core.c

+4 −0
Original line number Diff line number Diff line
@@ -564,6 +564,8 @@ void resched_task(struct task_struct *p) 


	if (set_nr_and_not_polling(p))

		smp_send_reschedule(cpu);

	else

		trace_sched_wake_idle_without_ipi(cpu);

}



void resched_cpu(int cpu)
@@ -647,6 +649,8 @@ static void wake_up_idle_cpu(int cpu) 
	smp_mb();

	if (!tsk_is_polling(rq->idle))

		smp_send_reschedule(cpu);

	else

		trace_sched_wake_idle_without_ipi(cpu);

}



static bool wake_up_full_nohz_cpu(int cpu)