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 <fweis...@gmail.com>
Cc: Chris Metcalf <cmetc...@tilera.com>
Cc: Christoph Lameter <c...@linux.com>
Cc: Geoff Levand <ge...@infradead.org>
Cc: Gilad Ben Yossef <gi...@benyossef.com>
Cc: Hakan Akkan <hakanak...@gmail.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Kevin Hilman <khil...@linaro.org>
Cc: Li Zhong <zh...@linux.vnet.ibm.com>
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortma...@windriver.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Stephane Eranian <eran...@google.com>
Cc: Jiri Olsa <jo...@redhat.com>
---
 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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