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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 E34D6C2BB40 for ; Thu, 17 Dec 2020 06:53:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AADBF23603 for ; Thu, 17 Dec 2020 06:53:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727359AbgLQGxC (ORCPT ); Thu, 17 Dec 2020 01:53:02 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:9628 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726569AbgLQGxB (ORCPT ); Thu, 17 Dec 2020 01:53:01 -0500 Received: from DGGEMS403-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4CxN2M5Ghnz15YMZ; Thu, 17 Dec 2020 14:51:39 +0800 (CST) Received: from [10.174.176.199] (10.174.176.199) by DGGEMS403-HUB.china.huawei.com (10.3.19.203) with Microsoft SMTP Server id 14.3.498.0; Thu, 17 Dec 2020 14:52:10 +0800 Subject: Re: [PATCH] tick/nohz: Make the idle_exittime update correctly To: Frederic Weisbecker CC: , , , , Shiyuan Hu , Hewenliang References: <2e194669-c074-069c-4fda-ad5bc313a611@huawei.com> <20201215144757.GA9391@lothringen> From: Yunfeng Ye Message-ID: Date: Thu, 17 Dec 2020 14:51:58 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20201215144757.GA9391@lothringen> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.176.199] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/12/15 22:47, Frederic Weisbecker wrote: > On Tue, Dec 15, 2020 at 08:06:34PM +0800, Yunfeng Ye wrote: >> The idle_exittime field of tick_sched is used to record the time when >> the idle state was left. but currently the idle_exittime is updated in >> the function tick_nohz_restart_sched_tick(), which is not always in idle >> state when nohz_full is configured. >> >> tick_irq_exit >> tick_nohz_irq_exit >> tick_nohz_full_update_tick >> tick_nohz_restart_sched_tick >> ts->idle_exittime = now; >> >> So move to tick_nohz_stop_idle() to make the idle_exittime update >> correctly. >> >> Signed-off-by: Yunfeng Ye >> --- >> kernel/time/tick-sched.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c >> index 749ec2a583de..be2e5d772d50 100644 >> --- a/kernel/time/tick-sched.c >> +++ b/kernel/time/tick-sched.c >> @@ -591,6 +591,7 @@ static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now) >> { >> update_ts_time_stats(smp_processor_id(), ts, now, NULL); >> ts->idle_active = 0; >> + ts->idle_exittime = now; > > This changes a bit the meaning of idle_exittime then since this is also called > from idle interrupt entry. > > __tick_nohz_idle_restart_tick() would be a better place. > So is it necessary to modify the comment "@idle_exittime: Time when the idle state was left" ? On the other hand, if the patch "nohz: Update tick instead of restarting tick in tick_nohz_idle_exit()" (https://www.spinics.net/lists/kernel/msg3747039.html ) applied, __tick_nohz_idle_restart_tick will not be called always, So is it put here also a better place? Thanks. > Thanks. > >> >> sched_clock_idle_wakeup_event(); >> } >> @@ -901,7 +902,6 @@ static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now) >> * Cancel the scheduled timer and restore the tick >> */ >> ts->tick_stopped = 0; >> - ts->idle_exittime = now; >> >> tick_nohz_restart(ts, now); >> } >> -- >> 2.18.4 >> > . >