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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 F06ADC2D0C9 for ; Thu, 12 Dec 2019 10:14:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8436206A5 for ; Thu, 12 Dec 2019 10:14:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ga+Evak3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728501AbfLLKOh (ORCPT ); Thu, 12 Dec 2019 05:14:37 -0500 Received: from merlin.infradead.org ([205.233.59.134]:38562 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728492AbfLLKOh (ORCPT ); Thu, 12 Dec 2019 05:14:37 -0500 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=K6jZFAg3+p0myI/G02qDuSlT1qkjA4IZ0q8Ttj/RQVY=; b=ga+Evak3G5IkAduI0yvP2RS5z NzpaFvANNgvlv6NGFLsuNM/1H0kCLNGb8dK1VRlQPKvethOn1+KO3VeABT1XsfhYqt7wNr3P+/0MV 2jzfJiYEtk5REBp01Muj4fS3+D+A4rVgeLiSKFAzUdejgBwblxQ9Og/3N4rwEo9zXw9EU3Hf/878z D+giTsqspKO/GGG41yoUOXwrGZyjJEfNXvxAywdP9+bqlfQsEwBiJZpFktUz532lsH83pzMnmvM1U tc5hwe65dyjwvzLR/0l1PvOkCbCg3bvo0sGDrwyX44JtC2bHwGtEYUdkXNZP+ybIcIg4DhUhqxBfS pENgyza3w==; 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 1ifLUH-0007Cv-Vs; Thu, 12 Dec 2019 10:14:26 +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 85515300F29; Thu, 12 Dec 2019 11:13:04 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CCCBD2012196F; Thu, 12 Dec 2019 11:14:24 +0100 (CET) Date: Thu, 12 Dec 2019 11:14:24 +0100 From: Peter Zijlstra To: Dave Chinner Cc: Srikar Dronamraju , Phil Auld , Ming Lei , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, Jeff Moyer , Dave Chinner , Eric Sandeen , Christoph Hellwig , Jens Axboe , Ingo Molnar , Tejun Heo , Vincent Guittot Subject: Re: [PATCH v4] sched/core: Preempt current task in favour of bound kthread Message-ID: <20191212101424.GH2871@hirez.programming.kicks-ass.net> References: <20191120191636.GI4097@hirez.programming.kicks-ass.net> <20191120220313.GC18056@pauld.bos.csb> <20191121132937.GW4114@hirez.programming.kicks-ass.net> <20191209165122.GA27229@linux.vnet.ibm.com> <20191209231743.GA19256@dread.disaster.area> <20191210054330.GF27253@linux.vnet.ibm.com> <20191210172307.GD9139@linux.vnet.ibm.com> <20191211173829.GB21797@linux.vnet.ibm.com> <20191211224617.GE19256@dread.disaster.area> <20191212101031.GV2827@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191212101031.GV2827@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, Dec 12, 2019 at 11:10:31AM +0100, Peter Zijlstra wrote: > @@ -4156,13 +4159,13 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) > if (delta_exec < sysctl_sched_min_granularity) > return; > > - se = __pick_first_entity(cfs_rq); > + se = __pick_next_entity(cfs_rq, NULL); > delta = curr->vruntime - se->vruntime; > > if (delta < 0) > return; What I mean with the below comment is, when this isn't enough, try something like: if (se == cfs_rq->next) ideal_runtime /= 2; to make it yield sooner to 'next' buddies. Sadly, due to the whole cgroup mess, we can't say what actual task is on the end of it (without doing a full hierarchy pick, which is more expensive still). > - if (delta > ideal_runtime) > + if (delta > ideal_runtime) // maybe frob this too ? > resched_curr(rq_of(cfs_rq)); > }