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=-4.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 AB1F2C433E1 for ; Fri, 24 Jul 2020 08:12:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 850AA2074F for ; Fri, 24 Jul 2020 08:12:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="rYN++5sI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726938AbgGXIMs (ORCPT ); Fri, 24 Jul 2020 04:12:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726437AbgGXIMr (ORCPT ); Fri, 24 Jul 2020 04:12:47 -0400 Received: from mail-wm1-x342.google.com (mail-wm1-x342.google.com [IPv6:2a00:1450:4864:20::342]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C296C0619D3 for ; Fri, 24 Jul 2020 01:12:47 -0700 (PDT) Received: by mail-wm1-x342.google.com with SMTP id 184so7455619wmb.0 for ; Fri, 24 Jul 2020 01:12:47 -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=6m8MPunnWnimoI8Tr90cXlgJie5/8V6P4spqo5yR3oA=; b=rYN++5sI6uFsZ4lzSC5kXiJ2bIlfMMhlKCn6cNHsZsqhNTEctNRB3jXApCdZkY+Iga Aska2E6Dps0wUimqz4oyvDlKCvIv1eVON8R/sE6g1l5ULQqaFiCOcxrCVeJYU4pKNH5y dWjELZvKV1fakMBy0HsVzJ5w0RXquLc7JtpoW30NhYZRE26n37TFgE5FXNlkBQBNOhLK Lvk9FalQRsObfPi7+p65qFzEY/8K5nm+6Isx+F9+wsR5M3H6YGLl2CsmWPqSrDrJ6AlP Uf+xWmn4VnyRKITODbECoAoOzhYoYLzjpsvdGloKED79RF635kyqghHwHMbK8lo+P2fv yAFA== 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=6m8MPunnWnimoI8Tr90cXlgJie5/8V6P4spqo5yR3oA=; b=oOLSDbE9rjCTrDs75wjVTyKaxfog+IcIela/YNjxgCstymfSzPYk9IeWWQoXivS3J7 0quTbN4+ueIYz+Rrs13WeWgAfhwAPv6kd4s8AmAePi7iHA/ysyAoWvDSdxKsJDoO64t6 6pzD3jYKy4u2lJROYKZNM8WVXVNOmpp1QJbLhm2RX4CC+bVqO8BuNpywyNzMChyf++Mq sC/xnsjdKEgTZepP4qf9UOGK8QUgAeMW8l+XcpjXBn2b4eLLQ+bHxJ2P+g7rBMExGgWk ulqPYsOL854s2e1zzXDdKKwSrOzMsr3vzo+eK5WRuoJWHy9PRktupIKUSfGp7uN2DCmh b4fw== X-Gm-Message-State: AOAM531JuBj2xhsrTk7MNsCkD8IDTEljecEWfPGIQQU30xXrbFs5AEOe 6Y/zUw04eyBNy7GVRc7ECFyjACI9RAJ+1vLrZLA= X-Google-Smtp-Source: ABdhPJzmgBbim0+iQSTRtt3i8djYhE1SSkUXosg01WNCYrXcBmOWUTUgNIEZX6Xfv9R29wIEQKd4ExZpFGIodr0Y8js= X-Received: by 2002:a1c:28a:: with SMTP id 132mr7496150wmc.109.1595578366312; Fri, 24 Jul 2020 01:12:46 -0700 (PDT) MIME-Version: 1.0 References: <20200723233853.48815-1-humjb_1983@163.com> In-Reply-To: From: Jiang Biao Date: Fri, 24 Jul 2020 16:12:35 +0800 Message-ID: Subject: Re: [PATCH] sched/fair: consider sched-idle CPU when selecting idle core To: Vincent Guittot Cc: Jiang Biao , Ingo Molnar , Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , linux-kernel , Jiang Biao Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 24 Jul 2020 at 15:24, Vincent Guittot wrote: > > On Fri, 24 Jul 2020 at 01:39, Jiang Biao wrote: > > > > From: Jiang Biao > > > > Sched-idle CPU has been considered in select_idle_cpu and > > select_idle_smt, it also needs to be considered in select_idle_core to > > be consistent and keep the same *idle* policy. > > In the case of select_idle_core, we are looking for a core that is > fully idle but if one CPU of the core is running a sched_idle task, > the core will not be idle and we might end up having the wakeup task > on a CPU and a sched_idle task on another CPU of the core which is not > what we want Got it. sched_idle task may interfere its sibling, which brings me another question, If there's a core with smt1 running sched_idle task and smt2 idle, selecting smt1 rather than smt2 should be more helpful for wakee task, because wakee task could suppress the sched_idle task without neighbour interfering. And there seems to be no consideration about that currently. Is it worth improving that? Thanks a lot. Regards, Jiang