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 --- kernel/time/tick-sched.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/time') diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 1c9f53b2ddb..07929c63357 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -600,6 +600,13 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, time_delta = KTIME_MAX; } +#ifdef CONFIG_NO_HZ_FULL + if (!ts->inidle) { + time_delta = min(time_delta, + scheduler_tick_max_deferment()); + } +#endif + /* * calculate the expiry time for the next timer wheel * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals -- cgit v1.2.3