From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965433AbaDKN7D (ORCPT ); Fri, 11 Apr 2014 09:59:03 -0400 Received: from merlin.infradead.org ([205.233.59.134]:39762 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757761AbaDKNzw (ORCPT ); Fri, 11 Apr 2014 09:55:52 -0400 Message-Id: <20140411135218.546673774@infradead.org> User-Agent: quilt/0.60-1 Date: Fri, 11 Apr 2014 15:42:50 +0200 From: Peter Zijlstra To: mingo@kernel.org, tglx@linutronix.de, luto@amacapital.net, nicolas.pitre@linaro.org, daniel.lezcano@linaro.org, peterz@infradead.org, umgwanakikbuti@gmail.com Cc: linux-kernel@vger.kernel.org Subject: [RFC][PATCH 7/8] sched,idle: Delay clearing the polling bit References: <20140411134243.160989490@infradead.org> Content-Disposition: inline; filename=sched-idle-polling-fixup.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Cc: Nicolas Pitre Cc: Daniel Lezcano Cc: Thomas Gleixner Signed-off-by: Peter Zijlstra --- kernel/sched/idle.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) --- 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();