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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 95339C433DF for ; Thu, 2 Jul 2020 18:29:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 777F9207E8 for ; Thu, 2 Jul 2020 18:29:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728065AbgGBS3J (ORCPT ); Thu, 2 Jul 2020 14:29:09 -0400 Received: from foss.arm.com ([217.140.110.172]:51594 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727005AbgGBS3I (ORCPT ); Thu, 2 Jul 2020 14:29:08 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B714A1FB; Thu, 2 Jul 2020 11:29:07 -0700 (PDT) Received: from [192.168.178.2] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B9BD33F71E; Thu, 2 Jul 2020 11:29:06 -0700 (PDT) Subject: Re: [PATCH v3 5/7] sched/topology: Add more flags to the SD degeneration mask To: Valentin Schneider , linux-kernel@vger.kernel.org Cc: mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org, morten.rasmussen@arm.com References: <20200701190656.10126-1-valentin.schneider@arm.com> <20200701190656.10126-6-valentin.schneider@arm.com> From: Dietmar Eggemann Message-ID: <3406fe6b-405b-d542-6459-732f4ae890f6@arm.com> Date: Thu, 2 Jul 2020 20:28:38 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200701190656.10126-6-valentin.schneider@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/07/2020 21:06, Valentin Schneider wrote: > I don't think it is going to change much in practice, but we were missing > those: > > o SD_BALANCE_WAKE: Used just like the other SD_BALANCE_* flags, so also > needs > 1 group. > o SD_ASYM_PACKING: Hinges on load balancing (periodic / wakeup), thus needs > > 1 group to happen > o SD_OVERLAP: Describes domains with overlapping groups; can't have > overlaps with a single group. > > SD_PREFER_SIBLING is as always the odd one out: we currently consider it > in sd_parent_degenerate() but not in sd_degenerate(). It too hinges on load > balancing, and thus won't have any effect when set on a domain with a > single group. Add it to the sd_degenerate() groups mask. > > Signed-off-by: Valentin Schneider > --- > kernel/sched/topology.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c > index 6047d491abe9..fe393b295444 100644 > --- a/kernel/sched/topology.c > +++ b/kernel/sched/topology.c > @@ -161,11 +161,15 @@ static int sd_degenerate(struct sched_domain *sd) > > /* Following flags need at least 2 groups */ > if (sd->flags & (SD_BALANCE_NEWIDLE | > + SD_BALANCE_WAKE | > SD_BALANCE_FORK | > SD_BALANCE_EXEC | > + SD_ASYM_PACKING | > SD_SHARE_CPUCAPACITY | > SD_ASYM_CPUCAPACITY | > - SD_SHARE_PKG_RESOURCES)) { > + SD_SHARE_PKG_RESOURCES | > + SD_OVERLAP | > + SD_PREFER_SIBLING)) { Why do you add SD_PREFER_SIBLING here? It doesn't have SDF_NEEDS_GROUPS set in [PATCH v3 6/7]. $ cat ./include/linux/sched/sd_flags.h | grep ^SD_FLAG SD_FLAG(SD_BALANCE_NEWIDLE, 0, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) SD_FLAG(SD_BALANCE_EXEC, 1, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) SD_FLAG(SD_BALANCE_FORK, 2, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) SD_FLAG(SD_BALANCE_WAKE, 3, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) SD_FLAG(SD_WAKE_AFFINE, 4, SDF_SHARED_CHILD) SD_FLAG(SD_ASYM_CPUCAPACITY, 5, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS) SD_FLAG(SD_SHARE_CPUCAPACITY, 6, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) SD_FLAG(SD_SHARE_PKG_RESOURCES, 7, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) SD_FLAG(SD_SERIALIZE, 8, SDF_SHARED_PARENT) SD_FLAG(SD_ASYM_PACKING, 9, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) SD_FLAG(SD_PREFER_SIBLING, 10, 0) <-- !!! SD_FLAG(SD_OVERLAP, 11, SDF_SHARED_PARENT |SDF_NEEDS_GROUPS) SD_FLAG(SD_NUMA, 12, SDF_SHARED_PARENT)