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

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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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2013-04-24 09:39:24 +02:00
commit 447a34a2b7
3 changed files with 37 additions and 4 deletions
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21
include/trace/events/timer.h
View File

@ -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 */

1
kernel/time/Kconfig
View File

@ -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

19
kernel/time/tick-sched.c
View File

@ -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, " ");
}
/*