From: Peter Zijlstra Date: Fri, 11 Apr 2014 11:47:16 +0000 (+0200) Subject: sched/idle: Delay clearing the polling bit X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c444117f0f39d59733ec23da67c44424df529230;p=linux.git sched/idle: Delay clearing the polling bit With the generic idle functions assuming !polling we should only clear the polling bit at the very last opportunity in order to avoid spurious IPIs. Ideally we'd flip the default to polling, but that means auditing all arch idle functions. Signed-off-by: Peter Zijlstra Acked-by: Nicolas Pitre Cc: Daniel Lezcano Cc: Linus Torvalds Link: http://lkml.kernel.org/n/tip-vq7719foqzf6z5h4j7eh7f9e@git.kernel.org Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 8f4390a079c77..ed67f0cd2906e 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -78,12 +78,10 @@ static int cpuidle_idle_call(void) /* * Check if the idle task must be rescheduled. If it is the - * case, exit the function after re-enabling the local irq and - * set again the polling flag + * case, exit the function after re-enabling the local irq. */ - if (current_clr_polling_and_test()) { + if (need_resched()) { local_irq_enable(); - __current_set_polling(); return 0; } @@ -127,7 +125,7 @@ static int cpuidle_idle_call(void) broadcast = !!(drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP); - if (broadcast) + if (broadcast) { /* * Tell the time framework to switch * to a broadcast timer because our @@ -139,6 +137,7 @@ static int cpuidle_idle_call(void) ret = clockevents_notify( CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu); + } if (!ret) { trace_cpu_idle_rcuidle(next_state, dev->cpu); @@ -175,8 +174,12 @@ static int cpuidle_idle_call(void) * We can't use the cpuidle framework, let's use the default * idle routine */ - if (ret) - arch_cpu_idle(); + if (ret) { + if (!current_clr_polling_and_test()) + arch_cpu_idle(); + else + local_irq_enable(); + } __current_set_polling();