Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 03/10] perf: New helper to prevent full dynticks CPUs from stopping tick | Date | Mon, 22 Apr 2013 20:59:39 +0200 |
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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> --- include/linux/perf_event.h | 6 ++++++ kernel/events/core.c | 10 ++++++++++ 2 files changed, 16 insertions(+), 0 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index e47ee46..0140830 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -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)) /* diff --git a/kernel/events/core.c b/kernel/events/core.c index 75b58bb..ddb993b 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -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); -- 1.7.5.4
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