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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, 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 21B69C433E0 for ; Mon, 11 Jan 2021 15:43:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1067206A4 for ; Mon, 11 Jan 2021 15:43:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732215AbhAKPnK (ORCPT ); Mon, 11 Jan 2021 10:43:10 -0500 Received: from mx2.suse.de ([195.135.220.15]:56006 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730693AbhAKPnJ (ORCPT ); Mon, 11 Jan 2021 10:43:09 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 64426AD8C; Mon, 11 Jan 2021 15:42:28 +0000 (UTC) Date: Mon, 11 Jan 2021 15:42:26 +0000 From: Mel Gorman To: Vincent Guittot Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, valentin.schneider@arm.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3 v2] sched/fair: don't set LBF_ALL_PINNED unnecessarily Message-ID: <20210111154226.GG3524@suse.de> References: <20210107103325.30851-1-vincent.guittot@linaro.org> <20210107103325.30851-3-vincent.guittot@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20210107103325.30851-3-vincent.guittot@linaro.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 07, 2021 at 11:33:24AM +0100, Vincent Guittot wrote: > Setting LBF_ALL_PINNED during active load balance is only valid when there > is only 1 running task on the rq otherwise this ends up increasing the > balance interval whereas other tasks could migrate after the next interval > once they become cache-cold as an example. > > LBF_ALL_PINNED flag is now always set it by default. It is then cleared > when we find one task that can be pulled when calling detach_tasks() or > during active migration. > > Signed-off-by: Vincent Guittot When reviewing this, I found it curious that sched_nr_migrate_break is a const instead of a #define. It's not clear why as it only appears to exist in case sysctl_sched_nr_migrate is set higher than 32 to prevent rq lock starvation. With your patch, s/atleast/at least/ in the comments if there is another version. Otherwise, I didn't spot a real problem so Acked-by: Mel Gorman -- Mel Gorman SUSE Labs