Kick the current CPU's tick by sending it a self IPI when
an event is queued on the rotation list and it is the first
element inserted. This makes sure that perf_event_task_tick()
works on full dynticks CPUs.

Signed-off-by: Frederic Weisbecker <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Geoff Levand <[email protected]>
Cc: Gilad Ben Yossef <[email protected]>
Cc: Hakan Akkan <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Kevin Hilman <[email protected]>
Cc: Li Zhong <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Jiri Olsa <[email protected]>
---
 kernel/events/core.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index b0cd865..75b58bb 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -18,6 +18,7 @@
 #include <linux/poll.h>
 #include <linux/slab.h>
 #include <linux/hash.h>
+#include <linux/tick.h>
 #include <linux/sysfs.h>
 #include <linux/dcache.h>
 #include <linux/percpu.h>
@@ -655,8 +656,12 @@ static void perf_pmu_rotate_start(struct pmu *pmu)
 
        WARN_ON(!irqs_disabled());
 
-       if (list_empty(&cpuctx->rotation_list))
+       if (list_empty(&cpuctx->rotation_list)) {
+               int was_empty = list_empty(head);
                list_add(&cpuctx->rotation_list, head);
+               if (was_empty)
+                       tick_nohz_full_kick();
+       }
 }
 
 static void get_ctx(struct perf_event_context *ctx)
-- 
1.7.5.4

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