From: Frederic Weisbecker <[email protected]> If we were running adaptive tickless but then we schedule out and enter the idle task, we don't need to restart the tick because tick_nohz_idle_enter() is going to be called right away.
The only thing we need to do is to save the jiffies such that when we later restart the tick we can account the CPU time spent while idle was tickless. Signed-off-by: Frederic Weisbecker <[email protected]> Cc: Alessio Igor Bogani <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Avi Kivity <[email protected]> Cc: Chris Metcalf <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Daniel Lezcano <[email protected]> Cc: Geoff Levand <[email protected]> Cc: Gilad Ben Yossef <[email protected]> Cc: Hakan Akkan <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Kevin Hilman <[email protected]> Cc: Max Krasnyansky <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephen Hemminger <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Sven-Thorsten Dietrich <[email protected]> Cc: Thomas Gleixner <[email protected]> --- kernel/time/tick-sched.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 2627663..16267ee 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -1036,14 +1036,18 @@ void tick_nohz_pre_schedule(void) void tick_nohz_post_schedule(void) { struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); + unsigned long flags; - /* - * No need to disable irqs here. The worst that can happen - * is an irq that comes and restart the tick before us. - * tick_nohz_restart_sched_tick() is irq safe. - */ - if (ts->tick_stopped) - tick_nohz_restart_sched_tick(); + local_irq_save(flags); + if (ts->tick_stopped) { + if (is_idle_task(current)) { + ts->saved_jiffies = jiffies; + ts->saved_jiffies_whence = JIFFIES_SAVED_IDLE; + } else { + tick_nohz_restart_sched_tick(); + } + } + local_irq_restore(flags); } void tick_nohz_flush_current_times(bool restart_tick) -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
