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 1734DC282D7 for ; Wed, 30 Jan 2019 17:40:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DFC1020870 for ; Wed, 30 Jan 2019 17:40:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linaro.org header.i=@linaro.org header.b="BcYnM5fS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732566AbfA3RkP (ORCPT ); Wed, 30 Jan 2019 12:40:15 -0500 Received: from mail-it1-f193.google.com ([209.85.166.193]:50514 "EHLO mail-it1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727765AbfA3RkP (ORCPT ); Wed, 30 Jan 2019 12:40:15 -0500 Received: by mail-it1-f193.google.com with SMTP id z7so584014iti.0 for ; Wed, 30 Jan 2019 09:40:14 -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=urdFLpwv0GrRunGhonLWDShWyTr8hx1Kry6uC6z8Isk=; b=BcYnM5fSbOTw/Jrg9N3wUAwLlR4jaCNwcnbp9qGm4v9SedPnHVxn7WuMNlVO1CSHzr PGCIxUabO0yAeL4XRRhF/Wd4AJ4cXxjxdNmPVJriGPG5T4z3YtqRfWcIF5XfBLsvxHSQ egQJuTSxLY1OcpHRj8EnAjglm6g/wUoUtu2B4= 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=urdFLpwv0GrRunGhonLWDShWyTr8hx1Kry6uC6z8Isk=; b=O27nQIvQWm03E2M9Rs6HlkT+R2xMWz47w2wMO20aaxaGpIbkCjBFdjpzYOQu8ZTil8 RR7BDH79O/NVcASSFoLEGzvhfVbGAearc4cMty1G6RPXgLL0BpGSXz2e7UHQ6EDhi8Pe 1KH7P/VXS7Rzzgc9YQerXTFxSb2C0AUdOBRcOevkzyaXwSwaEMs7ZYdjwrcfBkMAmlgT LZYw+ZLAuz1tg27rvJiIRMAO/PbG6cEyXuS2TuJEHEvYSqgwkLg9sWrIlx8AXBRbCtwV cBT0uBkCkaoa+19r9u6evlFndB9BswV+KM+koGXWnuU4fzQiOX3xqRK2J9NaLfUQconf rf7A== X-Gm-Message-State: AJcUukdRCOUl4WpOZXrQl7szaxFZ4IGk09h9RpuZxhor9twamiiUDtZo Hry8HyqN2Zy4nRsz6vZks4symrTaHbHEo3eq+bGTLA== X-Google-Smtp-Source: ALg8bN56MENFr3D4gZa0VhZgw7wyysTVtyuuWLF/ND+6PdCI858dapURVHfG8Ld7MX80u9MsQu35zt7caWEJCNBgu6Q= X-Received: by 2002:a24:a20e:: with SMTP id j14mr16847750itf.14.1548870013742; Wed, 30 Jan 2019 09:40:13 -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: From: Vincent Guittot Date: Wed, 30 Jan 2019 18:40:02 +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 15:27, Vincent Guittot wrote: > > 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; In fact tests show that we must keep: return rq->tmp_alone_branch == &rq->leaf_cfs_rq_list; Because the 1st sched_entity that will be used in the newly added for_each_sched_entity loop, can be the sched_entityof the cfs_rq that we just added in the list so cfs_rq->on_list == 1 but we must continue to add parent Apart from that, tests are ok > > > > > > + > > > + cfs_rq->on_list = 1; > > > > > > /* > > > * Ensure we either appear before our parent (if already