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=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 77AE8C4338F for ; Mon, 23 Aug 2021 17:40:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 59CEC61374 for ; Mon, 23 Aug 2021 17:40:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231337AbhHWRlO (ORCPT ); Mon, 23 Aug 2021 13:41:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230154AbhHWRlM (ORCPT ); Mon, 23 Aug 2021 13:41:12 -0400 Received: from mail-yb1-xb35.google.com (mail-yb1-xb35.google.com [IPv6:2607:f8b0:4864:20::b35]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F05CBC061575 for ; Mon, 23 Aug 2021 10:40:29 -0700 (PDT) Received: by mail-yb1-xb35.google.com with SMTP id i8so35632267ybt.7 for ; Mon, 23 Aug 2021 10:40:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Tg+gMiZppcg/miaZRd7SQo5vvbFPzzQYgyARNlwL+fs=; b=BvkQXvWLuF9rtvj03T1szkEg7VIAr77xKJrK0XfMggjkZ2WauaSTewIvd1ZsC3jzdb ONRkDxVgWIIRYmLFo/qHchfgT2guuWVVkegUXMNcLl7nmW6ILqgY7mrGBPoahyOVW/hS c/u+U6g9kcZuoFiBC9K5XHCl86rE7RziMvFb/oJiKI7ynif97ruW3FJ7Y7VXtFYlyRJi +WTrhgFnr8Dt1Sp5kQORdAphG6MLUMujObUx60cFvay5VyDkGGDoJw2tcSlIE7vcom5u DmRM8GY5MGoLatfM1mIMbLgAkyIv1dDskW19jErtROlBz4BR594HUh9+TSLtqDhLScMm oPcQ== 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=Tg+gMiZppcg/miaZRd7SQo5vvbFPzzQYgyARNlwL+fs=; b=AvmMuHuFO65qY9TD97IQP/jw45yqKjV9R50GOILeaUJcOVQ9L7uROy+nYltPz7ktrX iYBu8dfVNYlm3KYsy3fVOKlAvEBQdnJCTAsnXTPOjrrY0ntVJmEYJAGpnQNpGU/m7Ylk BOOiTcBRYW5m8yFzUX4QcLj7YEsPOhnSGjQOTOBazwORmdNoqzOZ2j7il/8pLaBch/4B cyj9+XyFrnUL11KOAH7+2ZOgMksL5DYD4vxHNycOd2JIdyzGefdf/yB8hvbkWfMcefTe lQHdIzhixCMoTZ0L4JZb3hRg+unvw4unpQNgTl0XlcTFpzTsNAs5irnkOI8iai3fee22 GdYQ== X-Gm-Message-State: AOAM530aQUoybXtavdxLWYHZAwcifcR20gCyjqZWk+r++l2ZWO6j+PVm wxoBrNoaqpqXx880s9P2NNT54sGtuC4TXDbwJZRaMw== X-Google-Smtp-Source: ABdhPJy6P+lNKnUyRQB1g78zhUeRoBAr2ERyd7psF4azuiMjorAMpI/sQYSe2S2Aal59EB1ztaXm6NrrKGRb1fsDQbU= X-Received: by 2002:a25:2155:: with SMTP id h82mr44910506ybh.177.1629740428956; Mon, 23 Aug 2021 10:40:28 -0700 (PDT) MIME-Version: 1.0 References: <20210820010403.946838-1-joshdon@google.com> <20210820010403.946838-4-joshdon@google.com> In-Reply-To: From: Josh Don Date: Mon, 23 Aug 2021 10:40:18 -0700 Message-ID: Subject: Re: [PATCH v3 3/4] sched: reduce sched slice for SCHED_IDLE entities To: Vincent Guittot Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Paul Turner , Oleg Rombakh , Viresh Kumar , Steve Sistare , Tejun Heo , Rik van Riel , linux-kernel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 23, 2021 at 3:08 AM Vincent Guittot wrote: > > On Fri, 20 Aug 2021 at 03:04, Josh Don wrote: > > > > @@ -684,12 +696,13 @@ static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) > > for_each_sched_entity(se) { > > struct load_weight *load; > > struct load_weight lw; > > + struct cfs_rq *qcfs_rq; > > > > - cfs_rq = cfs_rq_of(se); > > - load = &cfs_rq->load; > > + qcfs_rq = cfs_rq_of(se); > > + load = &qcfs_rq->load; > > > > if (unlikely(!se->on_rq)) { > > - lw = cfs_rq->load; > > + lw = qcfs_rq->load; > > > > update_load_add(&lw, se->load.weight); > > load = &lw; > > @@ -697,8 +710,14 @@ static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) > > slice = __calc_delta(slice, se->load.weight, load); > > } > > > > - if (sched_feat(BASE_SLICE)) > > - slice = max(slice, (u64)sysctl_sched_min_granularity); > > + if (sched_feat(BASE_SLICE)) { > > + if (se_is_idle(init_se) && !sched_idle_cfs_rq(cfs_rq)) > > Like for place_entity, we should probably not dynamically switch > between the 2 values below depending on the presence or not of non > sched idle tasks and always use sysctl_sched_idle_min_granularity My reasoning here is that sched_slice is something we reasonably expect to change as tasks enqueue/dequeue, and unlike place_entity() it does not create fairness issues by messing with vruntime. Additionally, it would be preferable to use the larger min granularity on a cpu running only idle tasks.