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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2018-03-15 23:07:41 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2018-04-05 19:01:29 +0200
commited98c34919985a9f87c3edacb9a8d8c283c9e243 (patch)
tree342bb5a1961b6c594a38706f7ed6a5048ae63f29 /kernel/sched
parent2aaf709a518d26563b80fd7a42379d7aa7ffed4a (diff)
downloadlinux-ed98c34919985a9f87c3edacb9a8d8c283c9e243.tar.bz2
sched: idle: Do not stop the tick before cpuidle_idle_call()
Make cpuidle_idle_call() decide whether or not to stop the tick. First, the cpuidle_enter_s2idle() path deals with the tick (and with the entire timekeeping for that matter) by itself and it doesn't need the tick to be stopped beforehand. Second, to address the issue with short idle duration predictions by the idle governor after the tick has been stopped, it will be necessary to change the ordering of cpuidle_select() with respect to tick_nohz_idle_stop_tick(). To prepare for that, put a tick_nohz_idle_stop_tick() call in the same branch in which cpuidle_select() is called. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/idle.c19
1 files changed, 15 insertions, 4 deletions
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 3777e83c0b5a..4f64835d38a8 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -141,13 +141,15 @@ static void cpuidle_idle_call(void)
}
/*
- * Tell the RCU framework we are entering an idle section,
- * so no more rcu read side critical sections and one more
+ * The RCU framework needs to be told that we are entering an idle
+ * section, so no more rcu read side critical sections and one more
* step to the grace period
*/
- rcu_idle_enter();
if (cpuidle_not_available(drv, dev)) {
+ tick_nohz_idle_stop_tick();
+ rcu_idle_enter();
+
default_idle_call();
goto exit_idle;
}
@@ -164,16 +166,26 @@ static void cpuidle_idle_call(void)
if (idle_should_enter_s2idle() || dev->use_deepest_state) {
if (idle_should_enter_s2idle()) {
+ rcu_idle_enter();
+
entered_state = cpuidle_enter_s2idle(drv, dev);
if (entered_state > 0) {
local_irq_enable();
goto exit_idle;
}
+
+ rcu_idle_exit();
}
+ tick_nohz_idle_stop_tick();
+ rcu_idle_enter();
+
next_state = cpuidle_find_deepest_state(drv, dev);
call_cpuidle(drv, dev, next_state);
} else {
+ tick_nohz_idle_stop_tick();
+ rcu_idle_enter();
+
/*
* Ask the cpuidle framework to choose a convenient idle state.
*/
@@ -240,7 +252,6 @@ static void do_idle(void)
tick_nohz_idle_restart_tick();
cpu_idle_poll();
} else {
- tick_nohz_idle_stop_tick();
cpuidle_idle_call();
}
arch_cpu_idle_exit();