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=-9.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 3D414C433DF for ; Thu, 15 Oct 2020 06:07:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C028E22249 for ; Thu, 15 Oct 2020 06:07:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="c/REDy8W" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726684AbgJOGHT (ORCPT ); Thu, 15 Oct 2020 02:07:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726053AbgJOGHT (ORCPT ); Thu, 15 Oct 2020 02:07:19 -0400 Received: from mail-io1-xd42.google.com (mail-io1-xd42.google.com [IPv6:2607:f8b0:4864:20::d42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF144C061755 for ; Wed, 14 Oct 2020 23:07:18 -0700 (PDT) Received: by mail-io1-xd42.google.com with SMTP id l8so2832436ioh.11 for ; Wed, 14 Oct 2020 23:07:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=gbDBjzfoSjYWcdFm7/OVUlPfbPckb1RRkf5R/cahnAo=; b=c/REDy8Wy+AgNbzLGLeWhbXSFuiyp0skQ+WxDIeQLskE83dYzmMTZF2ezUVBE84/4N hG5G4m5OON7XmxIbl6jRGt/9mQ2mJXi7GtO2iCSORVNwUoU3MHWVo+QyBtTJAO7LwXC+ Zn8Y5G8C094yR9GgvbjHL5ko12QDw0wuf7iWS9urkhVFapvgovTzwF94OeqoNnUY0iB6 4lfUEHSXeC3+ax7YnWWI26/gRXh091UkFetTXcOHHsHo/SFtUF+gRDFFPSrIS1/1Ajfq p1jm3fJDDOXxsyz04zYuDE3h832ATs9jXj7SYHajcKhta0jLIaTKsdQbIyIiTrQ54J8U zBKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=gbDBjzfoSjYWcdFm7/OVUlPfbPckb1RRkf5R/cahnAo=; b=AH+cCD3K/X9sSErnhOqzoGpKswbjC9XKiRyDLIbVpKYkUk3jpKpEmqfR9LN8dzMjWq Kg26ythJZazo7NQjeh2Uv6+CmPVFAV21dGaCSNeDyuIUAA42hI6EfTNsav4aOLGcfFqH lC6lHhHcuwYOONrRVqlKqPKZX0IU23xecsM+CyQOEsRoO3cVqwm0FO0mAZuiBrlh/9aP iExeZ6lCafa3w/fTZ1O+CIgmcvL/n47JcyMGTOXhEUY2yfrX4pzOcIfW6bV6Rg9IHrWt P/gUEawSTDmQZUgac9TCw3Eu/+T236b7rGbTcu9kpOC5OVMY/JJ+6PR/1bIYCcWjyihf B2kw== X-Gm-Message-State: AOAM532uDaLk3VVPjj+vhMnLmH8k50pB1EGZEV4URIpgX4uuOjZK1UPk thCBK1tzUg/vD+bpxgWoAHtpJmA30dVmEQwPw1E= X-Google-Smtp-Source: ABdhPJy9UlAIoHXd2nncLjwY3qAvV3ogTigQvb903Qwy6OPLA+FF/ndRaXdkq46BsqRDnv3F1JQ1Mje4WQcmzHsyexs= X-Received: by 2002:a02:ccac:: with SMTP id t12mr2234843jap.109.1602742038156; Wed, 14 Oct 2020 23:07:18 -0700 (PDT) MIME-Version: 1.0 References: <20201009092530.223-1-qianjun.kernel@gmail.com> <20201014131910.GG2628@hirez.programming.kicks-ass.net> In-Reply-To: <20201014131910.GG2628@hirez.programming.kicks-ass.net> From: Yafang Shao Date: Thu, 15 Oct 2020 14:06:42 +0800 Message-ID: Subject: Re: [PATCH 1/1] Sched/fair: Improve the accuracy of sched_stat_wait statistics To: Peter Zijlstra Cc: jun qian , Ingo Molnar , juri.lelli@redhat.com, Vincent Guittot , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 14, 2020 at 9:19 PM Peter Zijlstra wrote: > > On Fri, Oct 09, 2020 at 05:25:30PM +0800, qianjun.kernel@gmail.com wrote: > > From: jun qian > > > > When the sched_schedstat changes from 0 to 1, some sched se maybe > > already in the runqueue, the se->statistics.wait_start will be 0. > > So it will let the (rq_of(cfs_rq)) - se->statistics.wait_start) > > wrong. We need to avoid this scenario. > > > > Signed-off-by: jun qian > > Signed-off-by: Yafang Shao > > This SoB chain isn't valid. Did Yafang's tag need to a reviewed-by or > something? > This patch improves the behavior when sched_schedstat is changed from 0 to 1, so it looks good to me. Reviewed-by: Yafang Shao > > --- > > kernel/sched/fair.c | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 1a68a05..6f8ca0c 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -906,6 +906,15 @@ static void update_curr_fair(struct rq *rq) > > if (!schedstat_enabled()) > > return; > > > > + /* > > + * When the sched_schedstat changes from 0 to 1, some sched se > > + * maybe already in the runqueue, the se->statistics.wait_start > > + * will be 0.So it will let the delta wrong. We need to avoid this > > + * scenario. > > + */ > > + if (unlikely(!schedstat_val(se->statistics.wait_start))) > > + return; > > + > > delta = rq_clock(rq_of(cfs_rq)) - schedstat_val(se->statistics.wait_start); > > > > if (entity_is_task(se)) { > > -- > > 1.8.3.1 > > -- Thanks Yafang