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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 A5BFECA9EC9 for ; Wed, 30 Oct 2019 15:58:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 80C5C217D9 for ; Wed, 30 Oct 2019 15:58:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729326AbfJ3P6f (ORCPT ); Wed, 30 Oct 2019 11:58:35 -0400 Received: from outbound-smtp04.blacknight.com ([81.17.249.35]:51993 "EHLO outbound-smtp04.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728578AbfJ3P6c (ORCPT ); Wed, 30 Oct 2019 11:58:32 -0400 Received: from mail.blacknight.com (pemlinmail06.blacknight.ie [81.17.255.152]) by outbound-smtp04.blacknight.com (Postfix) with ESMTPS id ABD2F9871D for ; Wed, 30 Oct 2019 15:58:30 +0000 (GMT) Received: (qmail 2809 invoked from network); 30 Oct 2019 15:58:30 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.19.210]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 30 Oct 2019 15:58:30 -0000 Date: Wed, 30 Oct 2019 15:58:29 +0000 From: Mel Gorman To: Vincent Guittot Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, pauld@redhat.com, valentin.schneider@arm.com, srikar@linux.vnet.ibm.com, quentin.perret@arm.com, dietmar.eggemann@arm.com, Morten.Rasmussen@arm.com, hdanton@sina.com, parth@linux.ibm.com, riel@surriel.com Subject: Re: [PATCH v4 06/11] sched/fair: use load instead of runnable load in load_balance Message-ID: <20191030155829.GL3016@techsingularity.net> References: <1571405198-27570-1-git-send-email-vincent.guittot@linaro.org> <1571405198-27570-7-git-send-email-vincent.guittot@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1571405198-27570-7-git-send-email-vincent.guittot@linaro.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 18, 2019 at 03:26:33PM +0200, Vincent Guittot wrote: > runnable load has been introduced to take into account the case > where blocked load biases the load balance decision which was selecting > underutilized group with huge blocked load whereas other groups were > overloaded. > > The load is now only used when groups are overloaded. In this case, > it's worth being conservative and taking into account the sleeping > tasks that might wakeup on the cpu. > > Signed-off-by: Vincent Guittot Hmm.... ok. Superficially I get what you're doing but worry slightly about groups that have lots of tasks that are frequently idling on short periods of IO. Unfortuntely when I queued this series for testing I did not queue a load that idles rapidly for short durations that would highlight problems in that area. I cannot convince myself it's ok enough for an ack but I have no reason to complain either. -- Mel Gorman SUSE Labs