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perf: New helper to prevent full dynticks CPUs from stopping tick

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Provide a new helper that help full dynticks CPUs to prevent
from stopping their tick in case there are events in the local
rotation list.

This way we make sure that perf_event_task_tick() is serviced
on demand.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
This commit is contained in:
Frederic Weisbecker 2013-04-20 15:58:34 +02:00
parent 12351ef8f9
commit 026249ef10
2 changed files with 16 additions and 0 deletions
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6
include/linux/perf_event.h
View file

@ -799,6 +799,12 @@ static inline int __perf_event_disable(void *info) { return -1; }
static inline void perf_event_task_tick(void) { }
#endif
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_NO_HZ_FULL)
extern bool perf_event_can_stop_tick(void);
#else
static inline bool perf_event_can_stop_tick(void) { return true; }
#endif
#define perf_output_put(handle, x) perf_output_copy((handle), &(x), sizeof(x))
/*

10
kernel/events/core.c
View file

@ -2560,6 +2560,16 @@ done:
list_del_init(&cpuctx->rotation_list);
}
#ifdef CONFIG_NO_HZ_FULL
bool perf_event_can_stop_tick(void)
{
if (list_empty(&__get_cpu_var(rotation_list)))
return true;
else
return false;
}
#endif
void perf_event_task_tick(void)
{
struct list_head *head = &__get_cpu_var(rotation_list);