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authorFrederic Weisbecker <fweisbec@gmail.com>2013-05-03 03:39:05 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2013-05-04 08:32:02 +0200
commit265f22a975c1e4cc3a4d1f94a3ec53ffbb6f5b9f (patch)
treec5b7ec6b64fc31e879e730d2edf8e836cfaf7e9b /kernel/time
parent73c30828771acafb0a5e3a1c4cf75e6c5dc5f98a (diff)
downloadlinaro-lsk-265f22a975c1e4cc3a4d1f94a3ec53ffbb6f5b9f.tar.gz
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 <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/tick-sched.c7
1 files changed, 7 insertions, 0 deletions
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