From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8E7AC433E1 for ; Tue, 16 Jun 2020 03:35:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C8F0A20776 for ; Tue, 16 Jun 2020 03:35:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726523AbgFPDfM (ORCPT ); Mon, 15 Jun 2020 23:35:12 -0400 Received: from mga11.intel.com ([192.55.52.93]:52889 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725978AbgFPDfL (ORCPT ); Mon, 15 Jun 2020 23:35:11 -0400 IronPort-SDR: qrSRGl4HxCHfMbhbthB2zx4G1tFIlwgrEeupE16Kr8Cdj9w6E3gWBNesAFWYHE/+25dkrUzpl+ V/MvJoxZVfjQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jun 2020 20:35:11 -0700 IronPort-SDR: 4bJt/MCnL6bzAU78afso5FW3yO3Ka6xGQi7hHHorxubxslqyLyG0spDfIyZ39w6VKu2d+l8URQ c9YieamPPi2g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,517,1583222400"; d="scan'208";a="476275786" Received: from chenyu-office.sh.intel.com ([10.239.158.173]) by fmsmga005.fm.intel.com with ESMTP; 15 Jun 2020 20:35:09 -0700 Date: Tue, 16 Jun 2020 11:36:18 +0800 From: Chen Yu To: Peter Zijlstra Cc: "Rafael J. Wysocki" , Daniel Lezcano , Ingo Molnar , Len Brown , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH][RFC] PM / s2idle: Clear _TIF_POLLING_NRFLAG before suspend to idle Message-ID: <20200616033618.GA20959@chenyu-office.sh.intel.com> References: <20200615173611.15349-1-yu.c.chen@intel.com> <20200615184041.GG2531@hirez.programming.kicks-ass.net> <20200615193154.GJ2554@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200615193154.GJ2554@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 15, 2020 at 09:31:54PM +0200, Peter Zijlstra wrote: > On Mon, Jun 15, 2020 at 08:40:41PM +0200, Peter Zijlstra wrote: > > > > @@ -186,8 +187,10 @@ int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev) > > > * be frozen safely. > > > */ > > > index = find_deepest_state(drv, dev, U64_MAX, 0, true); > > > - if (index > 0) > > > + if (index > 0) { > > > + __current_clr_polling(); > > > enter_s2idle_proper(drv, dev, index); > > > + } > > > > > > return index; > > > } > > > > So how is that commit 08e237fa56a1 not suffient? That makes > > mwait_idle_with_hints() DTRT for this 'functionally challenged' piece of > > hardware. > > > > AFAICT intel_enter_s2idle() uses mwait_idle_with_hints(). > > > > What am I missing? > > What's missing is that cpuidle_enter_s2idle() doesn't properly match > call_cpuidle(). > Right. > Something like so then. Your version is racy, if someone already set > TIF_NEED_RESCHED you just clear POLLING and go to sleep. > Got it, I'll test the patch below. Thanks, Chenyu > --- > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > index c149d9e20dfd..81bee8d03c6d 100644 > --- a/drivers/cpuidle/cpuidle.c > +++ b/drivers/cpuidle/cpuidle.c > @@ -133,8 +133,8 @@ int cpuidle_find_deepest_state(struct cpuidle_driver *drv, > } > > #ifdef CONFIG_SUSPEND > -static void enter_s2idle_proper(struct cpuidle_driver *drv, > - struct cpuidle_device *dev, int index) > +static void s2idle_enter(struct cpuidle_driver *drv, > + struct cpuidle_device *dev, int index) > { > ktime_t time_start, time_end; > > @@ -168,6 +168,15 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv, > dev->states_usage[index].s2idle_usage++; > } > > +static int call_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev, > + int index) > +{ > + if (!current_clr_polling_and_test()) > + s2idle_enter(drv, dev, index); > + > + return index; > +} > + > /** > * cpuidle_enter_s2idle - Enter an idle state suitable for suspend-to-idle. > * @drv: cpuidle driver for the given CPU. > @@ -187,7 +196,7 @@ int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev) > */ > index = find_deepest_state(drv, dev, U64_MAX, 0, true); > if (index > 0) > - enter_s2idle_proper(drv, dev, index); > + call_s2idle(drv, dev, index); > > return index; > }