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: Ingo Molnar <mingo@kernel.org>
diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index 425bcfe..f5eb53e 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -323,6 +323,27 @@
(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 */
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index f6a792a..e1ac129 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -110,6 +110,7 @@
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
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 12a900d..85e05ab 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -28,6 +28,8 @@
#include "tick-internal.h"
+#include <trace/events/timer.h>
+
/*
* Per cpu nohz control structure
*/
@@ -153,14 +155,20 @@
{
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 @@
* 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 @@
ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
ts->tick_stopped = 1;
+ trace_tick_stop(1, " ");
}
/*