[RFC PATCH 07/11] nohz,timer: designate timer housekeeping cpu

[riel@redhat.com]

From: Rik van Riel <riel@redhat.com>

The timer housekeeping CPU can do tick based sampling for remote
CPUs. For now this is the first CPU in the housekeeping_mask.

Eventually we could move to having one timer housekeeping cpu per
socket, if needed.

Signed-off-by: Rik van Riel <riel@redhat.com>
---
 include/linux/tick.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/tick.h b/include/linux/tick.h
index f8492da57ad3..2fb51030587b 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -158,6 +158,15 @@ static inline bool is_housekeeping_cpu(int cpu)
 	return true;
 }
 
+static inline bool is_timer_housekeeping_cpu(int cpu)
+{
+#ifdef CONFIG_NO_HZ_FULL
+	if (tick_nohz_full_running)
+		return (cpumask_first(housekeeping_mask) == cpu);
+#endif
+	return false;
+}
+
 static inline void housekeeping_affine(struct task_struct *t)
 {
 #ifdef CONFIG_NO_HZ_FULL
-- 
2.1.0