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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 9DB36C433E0 for ; Wed, 6 Jan 2021 16:12:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5DA002312F for ; Wed, 6 Jan 2021 16:12:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727148AbhAFQME (ORCPT ); Wed, 6 Jan 2021 11:12:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44786 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726251AbhAFQME (ORCPT ); Wed, 6 Jan 2021 11:12:04 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ECC9BC06134C for ; Wed, 6 Jan 2021 08:11:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=+qfyMs5FDgoaco8XbmopXuzDpnstYMRh4Uqdozaw48Q=; b=cfS+8NKNIyjueFubKoNIY/8dwW 4sY+B79+qt7Fy8e8VGegR0z37jeWagFOWSMdT9SSgzNQ+pbGeUK87HlB3RFn1idn8aj+N7t7TKcZx ylxVPalDbHIuHBZ5JdQ27WiSiFWy6PTGPu9xutAFY/+iCWlytsGpP9J7LMsJ6hiq7D6Q22mxQwOHv EVIRiAEGlw8/uwKVWHTbNYnFG0my4GQElFrh11I4zi2HbAZE2m+lAiMSJMK2vjGQvByz0UlusLL4M Vp8py+u3GGd2I9BcaefMWsjZ986jPJNcDUWpHsp7zWgJrwQskRlv3pu5WpMk/UvKAlOM6cte2PNrF NkNE4sEA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kxBOt-00071A-Ry; Wed, 06 Jan 2021 16:11:08 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id D94183013E5; Wed, 6 Jan 2021 17:11:03 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CDFE82029C723; Wed, 6 Jan 2021 17:11:03 +0100 (CET) Date: Wed, 6 Jan 2021 17:11:03 +0100 From: Peter Zijlstra To: Vincent Guittot Cc: Ingo Molnar , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , linux-kernel Subject: Re: [PATCH 3/3] sched/fair: reduce cases for active balance Message-ID: References: <20210106133419.2971-1-vincent.guittot@linaro.org> <20210106133419.2971-4-vincent.guittot@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 06, 2021 at 04:41:04PM +0100, Vincent Guittot wrote: > Let me try again: > > Active balance is triggered for a number of voluntary cases like > misfit or pinned tasks cases but also after that a number of load > balance attempts failed to migrate a task. There is no need to use > active load balance when the group is overloaded because an overloaded > state means that there is at least one waiting task. Nevertheless, the > waiting task is not selected and detached until the threshold becomes > higher than its load. This threshold increases with the number of > failed lb (see the condition if ((load >> env->sd->nr_balance_failed) > > env->imbalance) in detach_tasks()) and the waiting task will end up > to be selected after a number of attempts. Ah, makes sense now. Thanks!