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

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>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index e47ee462c2f2..0140830225e2 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))
 
 /*