From 265f22a975c1e4cc3a4d1f94a3ec53ffbb6f5b9f Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 3 May 2013 03:39:05 +0200 Subject: sched: Keep at least 1 tick per second for active dynticks tasks The scheduler doesn't yet fully support environments with a single task running without a periodic tick. In order to ensure we still maintain the duties of scheduler_tick(), keep at least 1 tick per second. This makes sure that we keep the progression of various scheduler accounting and background maintainance even with a very low granularity. Examples include cpu load, sched average, CFS entity vruntime, avenrun and events such as load balancing, amongst other details handled in sched_class::task_tick(). This limitation will be removed in the future once we get these individual items to work in full dynticks CPUs. Suggested-by: Ingo Molnar Signed-off-by: Frederic Weisbecker Cc: Christoph Lameter Cc: Hakan Akkan Cc: Ingo Molnar Cc: Kevin Hilman Cc: Li Zhong Cc: Paul E. McKenney Cc: Paul Gortmaker Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner --- include/linux/sched.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index ebf7095158a9..af008d7bad57 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1862,6 +1862,7 @@ static inline void wake_up_nohz_cpu(int cpu) { } #ifdef CONFIG_NO_HZ_FULL extern bool sched_can_stop_tick(void); +extern u64 scheduler_tick_max_deferment(void); #else static inline bool sched_can_stop_tick(void) { return false; } #endif -- cgit v1.2.3