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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,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 1DA41C3E8C5 for ; Sat, 28 Nov 2020 01:16:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C943A20B80 for ; Sat, 28 Nov 2020 01:16:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727833AbgK1Aeh (ORCPT ); Fri, 27 Nov 2020 19:34:37 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:8190 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731450AbgK1Acd (ORCPT ); Fri, 27 Nov 2020 19:32:33 -0500 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4CjXVp2N3Dzkfrs; Sat, 28 Nov 2020 08:31:46 +0800 (CST) Received: from [10.174.176.199] (10.174.176.199) by DGGEMS407-HUB.china.huawei.com (10.3.19.207) with Microsoft SMTP Server id 14.3.487.0; Sat, 28 Nov 2020 08:32:05 +0800 Subject: Re: nohz: Update tick instead of restarting tick in tick_nohz_idle_exit() To: Frederic Weisbecker CC: , , , , Shiyuan Hu , Hewenliang References: <66014fea-7b84-358b-137d-d15190241528@huawei.com> <20201127121542.GA109224@lothringen> From: Yunfeng Ye Message-ID: <6d77dcc0-dea1-7b5e-9451-e4b21d7fb160@huawei.com> Date: Sat, 28 Nov 2020 08:32:05 +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: <20201127121542.GA109224@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 2020/11/27 20:15, Frederic Weisbecker wrote: > On Mon, Nov 23, 2020 at 09:22:08PM +0800, Yunfeng Ye wrote: >> In realtime scenarios, the "nohz_full" parameter is configured. Tick >> interference is not expected when there is only one realtime thread. >> But when the idle thread is switched to the realtime thread, the tick >> timer is restarted always. >> >> So on the nohz full mode, it is unnecessary to restart the tick timer >> when there is only one realtime thread. Adding can_stop_full_tick() >> before restarting the tick, if it return true, keep tick stopped. >> >> Signed-off-by: Yunfeng Ye > > We can indeed stop the tick and avoid it to be re-armed needlessly at this > point. > > I'm taking your patch, I may just edit it a little and resend it. > Ok, thanks. > Thanks! > . >