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Commit 447a34a2 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

Merge branch 'timers/nohz-help-testing' of... 

Merge branch 'timers/nohz-help-testing' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks

 into timers/nohz

Pull full dynticks helpers from Frederic Weisbecker:

 - handy tracepoints that allow dynticks analysis,
   to answer "why does my tick not stop??" questions

 - select CONFIG_RCU_NOCB_ALL

Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parents bf967be3 cb41a290

include/trace/events/timer.h

+21 −0
Original line number Diff line number Diff line
@@ -323,6 +323,27 @@ TRACE_EVENT(itimer_expire, 
		  (int) __entry->pid, (unsigned long long)__entry->now)

);



#ifdef CONFIG_NO_HZ_FULL

TRACE_EVENT(tick_stop,



	TP_PROTO(int success, char *error_msg),



	TP_ARGS(success, error_msg),



	TP_STRUCT__entry(

		__field( int ,		success	)

		__string( msg, 		error_msg )

	),



	TP_fast_assign(

		__entry->success	= success;

		__assign_str(msg, error_msg);

	),



	TP_printk("success=%s msg=%s",  __entry->success ? "yes" : "no", __get_str(msg))

);

#endif



#endif /*  _TRACE_TIMER_H */



/* This part must be outside protection */

kernel/time/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -110,6 +110,7 @@ config NO_HZ_FULL 
	select NO_HZ_COMMON

	select RCU_USER_QS

	select RCU_NOCB_CPU

	select RCU_NOCB_CPU_ALL

	select CONTEXT_TRACKING_FORCE

	select IRQ_WORK

	help

kernel/time/tick-sched.c

+15 −4
Original line number Diff line number Diff line
@@ -28,6 +28,8 @@ 


#include "tick-internal.h"



#include <trace/events/timer.h>



/*

 * Per cpu nohz control structure

 */
@@ -153,14 +155,20 @@ static bool can_stop_full_tick(void) 
{

	WARN_ON_ONCE(!irqs_disabled());



	if (!sched_can_stop_tick())

	if (!sched_can_stop_tick()) {

		trace_tick_stop(0, "more than 1 task in runqueue\n");

		return false;

	}



	if (!posix_cpu_timers_can_stop_tick(current))

	if (!posix_cpu_timers_can_stop_tick(current)) {

		trace_tick_stop(0, "posix timers running\n");

		return false;

	}



	if (!perf_event_can_stop_tick())

	if (!perf_event_can_stop_tick()) {

		trace_tick_stop(0, "perf events running\n");

		return false;

	}



	/* sched_clock_tick() needs us? */

#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
@@ -168,8 +176,10 @@ static bool can_stop_full_tick(void) 
	 * TODO: kick full dynticks CPUs when

	 * sched_clock_stable is set.

	 */

	if (!sched_clock_stable)

	if (!sched_clock_stable) {

		trace_tick_stop(0, "unstable sched clock\n");

		return false;

	}

#endif



	return true;
@@ -631,6 +641,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, 


			ts->last_tick = hrtimer_get_expires(&ts->sched_timer);

			ts->tick_stopped = 1;

			trace_tick_stop(1, " ");

		}



		/*