Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753148Ab3IKI5A (ORCPT ); Wed, 11 Sep 2013 04:57:00 -0400 Received: from merlin.infradead.org ([205.233.59.134]:39916 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751797Ab3IKI47 (ORCPT ); Wed, 11 Sep 2013 04:56:59 -0400 Date: Wed, 11 Sep 2013 10:56:43 +0200 From: Peter Zijlstra To: Mike Galbraith Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Thomas Gleixner , ethan.kernel@gmail.com, rjw@sisk.pl, daniel.lezcano@linaro.org, linux-pm@vger.kernel.org, lenb@kernel.org Subject: Re: [PATCH V3]hrtimer: Fix a performance regression by disable reprogramming in remove_hrtimer Message-ID: <20130911085643.GS26785@twins.programming.kicks-ass.net> References: <24EECBCC-F655-404F-8946-73CC36095A5F@gmail.com> <1378362989.18435.2.camel@marge.simpson.net> <20130905111428.GB23362@gmail.com> <1378386697.6567.9.camel@marge.simpson.net> <20130905133750.GA26637@gmail.com> <1378445942.5434.31.camel@marge.simpson.net> <20130909122325.GX31370@twins.programming.kicks-ass.net> <1378730538.5586.30.camel@marge.simpson.net> <20130909133044.GB31370@twins.programming.kicks-ass.net> <20130909134635.GB26785@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130909134635.GB26785@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1797 Lines: 44 On Mon, Sep 09, 2013 at 03:46:35PM +0200, Peter Zijlstra wrote: > On Mon, Sep 09, 2013 at 03:30:44PM +0200, Peter Zijlstra wrote: > > diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c > > index fa6964d..486c0ba 100644 > > --- a/drivers/idle/intel_idle.c > > +++ b/drivers/idle/intel_idle.c > > @@ -359,6 +359,14 @@ static int intel_idle(struct cpuidle_device *dev, > > if (!(lapic_timer_reliable_states & (1 << (cstate)))) > > clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu); > > > > + current_thread_into()->status |= TS_POLLING; > > + > > + /* > > + * Order against setting of TS_POLLING against the reading of > > + * NEED_RESCHED, matched by resched_task(). > > + */ > > + smp_mb(); > > + > > if (!need_resched()) { > > > > __monitor((void *)¤t_thread_info()->flags, 0, 0); > > @@ -367,6 +375,8 @@ static int intel_idle(struct cpuidle_device *dev, > > __mwait(eax, ecx); > > } > > > > + current_thread_into()->status &= ~TS_POLLING; > > + > > if (!(lapic_timer_reliable_states & (1 << (cstate)))) > > clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu); > > Hmm, arguably it would be better to set this from > intel_idle_cpuidle_driver_init() and clear it whenever this goes away. > Not sure how all that works, the cpuidle driver framework seems 'weird'. OK, so I went over the idle stuff again, and we do set TS_POLLING like stuff, it got hidden in current_{clr,set}_polling(). Still if that patch causes extra IPIs its bound to be broken in some creative way.. I'll prod. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/