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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D9A62C433DB for ; Fri, 19 Feb 2021 12:33:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AD6364EB8 for ; Fri, 19 Feb 2021 12:33:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230177AbhBSMdy (ORCPT ); Fri, 19 Feb 2021 07:33:54 -0500 Received: from mail.kernel.org ([198.145.29.99]:44292 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229681AbhBSMdw (ORCPT ); Fri, 19 Feb 2021 07:33:52 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id B373664E54; Fri, 19 Feb 2021 12:33:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1613737992; bh=pZIQqFujw5R6jSZxYrLEFYhYSZcD29FIGY6b7nQuEy0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=To+UdOopDsJaN/V46ujKSg9JZNVwaZIMT8PuYqagR+6ZwP2+gETbiIcijlnq5brTk LDhpLGZP01yzUiv0KrDbABnDTDTfOlL//EIBDJK/eVxOk1zgPEUnTtdRYyiMrSuCmr 0xguMliizKlpr66WKuoGtHe7KcxsfGlR6KE9MGU6TQdmiJjbSWxvTBdG1vHdBq0iWA wNDc5I1JglhFVVyKOV3bEmvJWAKNTSSFPVHU5EM2YFUhloDfNHbSLjfoCRsZ1J10K0 fRTyN7E/ovOKUoG5zh0BExytT9ZXtEeDPHBxleESYlyRNPSGvb9qckG65Fk25JArjX 1NiUgvKjJ+0SQ== Date: Fri, 19 Feb 2021 13:33:09 +0100 From: Frederic Weisbecker To: Yunfeng Ye Cc: fweisbec@gmail.com, tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org, Shiyuan Hu , Hewenliang Subject: Re: [PATCH] tick/nohz: Make the idle_exittime update correctly Message-ID: <20210219123309.GC51281@lothringen> References: <2e194669-c074-069c-4fda-ad5bc313a611@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2e194669-c074-069c-4fda-ad5bc313a611@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Dec 05, 2020 at 05:41:52PM +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; > > 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); > } Hi, I've edited and queued on top of latest changes, see below. I'll post it after the merge window. --- From: Yunfeng Ye Date: Wed, 10 Feb 2021 00:08:54 +0100 Subject: [PATCH] tick/nohz: Update idle_exittime on actual idle exit 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; It's thus overwritten by mistake on nohz_full tick restart. Move the update to the appropriate idle exit path instead. Signed-off-by: Yunfeng Ye Signed-off-by: Frederic Weisbecker --- kernel/time/tick-sched.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 79796286a4ba..2907c762a8fe 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -918,8 +918,6 @@ 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); } @@ -1231,6 +1229,7 @@ static void tick_nohz_idle_update_tick(struct tick_sched *ts, ktime_t now) else tick_nohz_restart_sched_tick(ts, now); + ts->idle_exittime = now; tick_nohz_account_idle_ticks(ts); } -- 2.25.1