The sequence of calls for dynticks CPUs was a bit confusing and so adding a comment in tick_nohz_idle_exit() routine to mention it clearly. All information required is in commit and this conversation with Frederic.
https://lkml.org/lkml/2014/4/10/355 Suggested-by: Frederic Weisbecker <fweis...@gmail.com> Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org> --- kernel/time/tick-sched.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index f1bc258..85a4e90 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -925,6 +925,22 @@ void tick_nohz_idle_exit(void) ts->inidle = 0; + /* + * Can idle_active be false here? + * Ideally this would be the sequence of calls: + * - tick_nohz_idle_enter(), i.e. idle_active = true; + * - local_irq_disable() + * - IDLE + * - wake up due to IPI or other interrupt + * - local_irq_enable() + * - tick_nohz_irq_enter(), i.e. idle_active = false; + * - tick_nohz_irq_exit(), i.e. idle_active = true; This is not called + * in case of IPI's as need_resched() will prevent that in + * tick_irq_exit(), as we don't need to account any more for idle time + * or try to enter dyntics mode (We are going to exit idle state). + * + * - tick_nohz_idle_exit() + */ if (ts->idle_active || ts->tick_stopped) now = ktime_get(); -- 1.7.12.rc2.18.g61b472e -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
