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=-0.8 required=3.0 tests=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 20C20C1B0F2 for ; Wed, 20 Jun 2018 09:08:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CBE2720652 for ; Wed, 20 Jun 2018 09:08:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CBE2720652 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754675AbeFTJIk (ORCPT ); Wed, 20 Jun 2018 05:08:40 -0400 Received: from foss.arm.com ([217.140.101.70]:34002 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752308AbeFTJGr (ORCPT ); Wed, 20 Jun 2018 05:06:47 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 34FC0164F; Wed, 20 Jun 2018 02:06:47 -0700 (PDT) Received: from e105550-lin.cambridge.arm.com (e105550-lin.cambridge.arm.com [10.1.211.30]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id B24CF3F246; Wed, 20 Jun 2018 02:06:45 -0700 (PDT) From: Morten Rasmussen To: peterz@infradead.org, mingo@redhat.com Cc: valentin.schneider@arm.com, dietmar.eggemann@arm.com, vincent.guittot@linaro.org, gaku.inami.xh@renesas.com, linux-kernel@vger.kernel.org, Morten Rasmussen Subject: [PATCHv3 5/9] sched/fair: Kick nohz balance if rq->misfit_task Date: Wed, 20 Jun 2018 10:05:45 +0100 Message-Id: <1529485549-5191-6-git-send-email-morten.rasmussen@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1529485549-5191-1-git-send-email-morten.rasmussen@arm.com> References: <1529485549-5191-1-git-send-email-morten.rasmussen@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Valentin Schneider There already are a few conditions in nohz_kick_needed() to ensure a nohz kick is triggered, but they are not enough for some misfit task scenarios. Excluding asym packing, those are: * rq->nr_running >=2: Not relevant here because we are running a misfit task, it needs to be migrated regardless and potentially through active balance. * sds->nr_busy_cpus > 1: If there is only the misfit task being run on a group of low capacity cpus, this will be evaluated to False. * rq->cfs.h_nr_running >=1 && check_cpu_capacity(): Not relevant here, misfit task needs to be migrated regardless of rt/IRQ pressure As such, this commit adds an rq->misfit_task condition to trigger a nohz kick. The idea to kick a nohz balance for misfit tasks originally came from Leo Yan , and a similar patch was submitted for the Android Common Kernel - see [1]. [1]: https://lists.linaro.org/pipermail/eas-dev/2016-September/000551.html cc: Ingo Molnar cc: Peter Zijlstra Signed-off-by: Valentin Schneider Signed-off-by: Morten Rasmussen --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 11f3efa299ca..b29d53d1e22a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9507,7 +9507,7 @@ static void nohz_balancer_kick(struct rq *rq) if (time_before(now, nohz.next_balance)) goto out; - if (rq->nr_running >= 2) { + if (rq->nr_running >= 2 || rq->misfit_task_load) { flags = NOHZ_KICK_MASK; goto out; } -- 2.7.4