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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 089CDC282D7 for ; Wed, 30 Jan 2019 14:27:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CCED420833 for ; Wed, 30 Jan 2019 14:27:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linaro.org header.i=@linaro.org header.b="DT5RkNZv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731169AbfA3O1Z (ORCPT ); Wed, 30 Jan 2019 09:27:25 -0500 Received: from mail-it1-f195.google.com ([209.85.166.195]:33693 "EHLO mail-it1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726332AbfA3O1Y (ORCPT ); Wed, 30 Jan 2019 09:27:24 -0500 Received: by mail-it1-f195.google.com with SMTP id m8so16788634itk.0 for ; Wed, 30 Jan 2019 06:27:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=EmMoE6fwKKEK5lfkDTrTiR8mVowCoseMK5e+Aa4eAHk=; b=DT5RkNZvROuYPfECyE8jP+VqbXH3dCau43BYWW0wZ2oHmbnGxoc3JitbwiQpegGqn5 iro7tOegw0lnHs8AV8v6sDi7muDoWvJ7KZz5bg5025MM7ldpKHyS9zm95N0/GpCnULce QUSPM9UhaHDFu8RtlKJAIeFIQWNQIjVh1b/mY= 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=EmMoE6fwKKEK5lfkDTrTiR8mVowCoseMK5e+Aa4eAHk=; b=j0A6RbBCq4JNEtqWqASgklSTDBczS34/TTydj+CLMJSePYSI5cEFezWtoPd511dRoi EfVYH3T6Fl7CAjNXI62F5eKmHs9OOYVG9Nr/Dg2ffzhTZba4dmAgTTkwxO4C4HQmIVEo h422ddrfkfNzboTbj1RAX2g8I6wtXNXcY888Coc0iznHMp1okqnJdY4ubNgiK6iRGcYW TjDgNHY9V4Jbh6Fc6rbyNhqbURlojHNIrWsQ1+aJtZHPMh2LVRH3gF16wlX4T+nnLnso 1P2IivUjhem4JZgfiV72DvccS5r2MSN4JaCGT5Mz0xo4fjW7vc2Ss2YCOZJQWPBbfT4O 7zww== X-Gm-Message-State: AJcUukd99/mav6SHtJn+y6F4EWWKZMQtUVbSgwdFwnIXZ0O5cVyCHPPO rGniQ6JIM8pN+yH0Ip51QDR5oyK45ByiWcs4/d90aCLugBkSEA== X-Google-Smtp-Source: ALg8bN63egVS24wIJzCak4gd65jcVIzt+Sa88X5z4QecoIvKR/4xF+Yuma/Tqqz4nGGf675Cl+8sPy8RmIF2uYFaGe0= X-Received: by 2002:a24:a20e:: with SMTP id j14mr16267055itf.14.1548858443691; Wed, 30 Jan 2019 06:27:23 -0800 (PST) MIME-Version: 1.0 References: <1548782332-18591-1-git-send-email-vincent.guittot@linaro.org> <1548825767-10799-1-git-send-email-vincent.guittot@linaro.org> <20190130140104.GB2296@hirez.programming.kicks-ass.net> <20190130140144.GD3103@hirez.programming.kicks-ass.net> In-Reply-To: <20190130140144.GD3103@hirez.programming.kicks-ass.net> From: Vincent Guittot Date: Wed, 30 Jan 2019 15:27:12 +0100 Message-ID: Subject: Re: [PATCH v2] sched/fair: Fix insertion in rq->leaf_cfs_rq_list To: Peter Zijlstra Cc: linux-kernel , Ingo Molnar , Tejun Heo , Sargun Dhillon 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 Wed, 30 Jan 2019 at 15:01, Peter Zijlstra wrote: > > On Wed, Jan 30, 2019 at 03:01:04PM +0100, Peter Zijlstra wrote: > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -282,13 +282,15 @@ static inline struct cfs_rq *group_cfs_r > > return grp->my_q; > > } > > > > -static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) > > +static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) > > { > > struct rq *rq = rq_of(cfs_rq); > > int cpu = cpu_of(rq); > > > > if (cfs_rq->on_list) > > - return; > > + return rq->tmp_alone_branch == &rq->leaf_cfs_rq_list; > > And I'm almost certain that can be: return true, but got my brain in a > twist. Yes this can return true If cfs_rq->on_list) then a child not already on the list used the path : if (cfs_rq->tg->parent && cfs_rq->tg->parent->cfs_rq[cpu]->on_list) { which does rq->tmp_alone_branch = &rq->leaf_cfs_rq_list; > > > + > > + cfs_rq->on_list = 1; > > > > /* > > * Ensure we either appear before our parent (if already