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=-5.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 B075FC17440 for ; Tue, 12 Nov 2019 10:58:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7B1AC2084E for ; Tue, 12 Nov 2019 10:58:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="nzvBKT4d" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726965AbfKLK6g (ORCPT ); Tue, 12 Nov 2019 05:58:36 -0500 Received: from mail-wm1-f66.google.com ([209.85.128.66]:37815 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726924AbfKLK6f (ORCPT ); Tue, 12 Nov 2019 05:58:35 -0500 Received: by mail-wm1-f66.google.com with SMTP id b17so2453314wmj.2 for ; Tue, 12 Nov 2019 02:58:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=O+4xsItenBrGg3gmgsiOonk74WScwaRcW0EVJaUE4nM=; b=nzvBKT4daXXNd0mSQaL3X0MixdV+M4+iJsvSG3tg6vwq1H7dEF5tQOX6zsseNYANjX 6kMaQcq7not6B6+yyYuQh6MR9OFTFyk6tDNVxwRK5gZUKswbs1kWqB2PRtavMcRdt04v u8ye2X5Dc1gTSIjFNFJ1xHhsTU/MEAd4wF5Gx5Zk1QEDpEQfIEuSCDD4jOzFxnPiO47o 4BdNfqjD21LolE+wffWgPRIMOJWquRBLWUSwxsKbDO9/ZKmNQQKiXdVdWNrx7jKWjTz7 DWvzoxNVrrwc68hwsXqDYiBEjfFfMmrFwUCH8MU2OA3E1A4RPbGZEDK05aL6BhLgkoW1 m8zw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=O+4xsItenBrGg3gmgsiOonk74WScwaRcW0EVJaUE4nM=; b=JmRnY2mFumGnlmmMaTYLTzTEKkMwteG4282MP3MlPqmRm+6R3ZntyWY+LcFV2lxwjS L4g1ncpXjt3F2kkn8Ii9FfigI4ZnqancUEF7i0oMspQiMBCRLxVs8hCz7FbJY+TL3a79 o2ZyIuuMum/4drgrGMXMJ5Kdmy12t1UDlgRndjYTjP5rAygDOaPYMZCZ26Ew3BOz6Pan jRElMb0prqH4rfPdYPHjUY3xGcgktANvR54dr+Xhqy91G+KJN9JmjpX9+GuH7SxXtYXr 5QqMXHK+5d9yfkYEIJaJtrIsQCEGSYqg7lBBfGcs4amPG0gKwDmq4NjahX78E7hjpVmy B3YA== X-Gm-Message-State: APjAAAV1co/o8w7LaDRrYzQ0rQ8Lqt2mTjnYAonm1lecz2U+U0eHO9VW HoKhkKIQjJqTXuD+kCetug3Kig== X-Google-Smtp-Source: APXvYqzZpWVd6uL0HdF6ijognCcoddQ3ekSAK19YNrQ6ja6f3/tDTMUlaf6G9S5MSBinXxhn7gH89Q== X-Received: by 2002:a1c:a4c5:: with SMTP id n188mr3332074wme.30.1573556312811; Tue, 12 Nov 2019 02:58:32 -0800 (PST) Received: from linaro.org ([2a01:e0a:f:6020:e45f:4180:5590:a312]) by smtp.gmail.com with ESMTPSA id t24sm44535148wra.55.2019.11.12.02.58.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Nov 2019 02:58:31 -0800 (PST) Date: Tue, 12 Nov 2019 11:58:30 +0100 From: Vincent Guittot To: Mel Gorman Cc: linux-kernel , Ingo Molnar , Peter Zijlstra , Phil Auld , Valentin Schneider , Srikar Dronamraju , Quentin Perret , Dietmar Eggemann , Morten Rasmussen , Hillf Danton , Parth Shah , Rik van Riel Subject: Re: [PATCH v4 04/11] sched/fair: rework load_balance Message-ID: <20191112105830.GA8765@linaro.org> References: <1571405198-27570-1-git-send-email-vincent.guittot@linaro.org> <1571405198-27570-5-git-send-email-vincent.guittot@linaro.org> <20191030154534.GJ3016@techsingularity.net> <20191031101544.GP3016@techsingularity.net> <20191031114020.GQ3016@techsingularity.net> <20191108163501.GA26528@linaro.org> <20191108183730.GU3016@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20191108183730.GU3016@techsingularity.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le Friday 08 Nov 2019 à 18:37:30 (+0000), Mel Gorman a écrit : > On Fri, Nov 08, 2019 at 05:35:01PM +0100, Vincent Guittot wrote: > > > Fair enough, netperf hits the corner case where it does not work but > > > that is also true without your series. > > > > I run mmtest/netperf test on my setup. It's a mix of small positive or > > negative differences (see below) > > > > > > > > netperf-tcp > > 5.3-rc2 5.3-rc2 > > tip +rwk+fix > > Hmean 64 871.30 ( 0.00%) 860.90 * -1.19%* > > Hmean 128 1689.39 ( 0.00%) 1679.31 * -0.60%* > > Hmean 256 3199.59 ( 0.00%) 3241.98 * 1.32%* > > Hmean 1024 9390.47 ( 0.00%) 9268.47 * -1.30%* > > Hmean 2048 13373.95 ( 0.00%) 13395.61 * 0.16%* > > Hmean 3312 16701.30 ( 0.00%) 17165.96 * 2.78%* > > Hmean 4096 15831.03 ( 0.00%) 15544.66 * -1.81%* > > Hmean 8192 19720.01 ( 0.00%) 20188.60 * 2.38%* > > Hmean 16384 23925.90 ( 0.00%) 23914.50 * -0.05%* > > Stddev 64 7.38 ( 0.00%) 4.23 ( 42.67%) > > Stddev 128 11.62 ( 0.00%) 10.13 ( 12.85%) > > Stddev 256 34.33 ( 0.00%) 7.94 ( 76.88%) > > Stddev 1024 35.61 ( 0.00%) 116.34 (-226.66%) > > Stddev 2048 285.30 ( 0.00%) 80.50 ( 71.78%) > > Stddev 3312 304.74 ( 0.00%) 449.08 ( -47.36%) > > Stddev 4096 668.11 ( 0.00%) 569.30 ( 14.79%) > > Stddev 8192 733.23 ( 0.00%) 944.38 ( -28.80%) > > Stddev 16384 553.03 ( 0.00%) 299.44 ( 45.86%) > > > > 5.3-rc2 5.3-rc2 > > tip +rwk+fix > > Duration User 138.05 140.95 > > Duration System 1210.60 1208.45 > > Duration Elapsed 1352.86 1352.90 > > > > This roughly matches what I've seen. The interesting part to me for > netperf is the next section of the report that reports the locality of > numa hints. With netperf on a 2-socket machine, it's generally around > 50% as the client/server are pulled apart. Because netperf is not > heavily memory bound, it doesn't have much impact on the overall > performance but it's good at catching the cross-node migrations. Ok. I didn't want to make my reply too long. I have put them below for the netperf-tcp results: 5.3-rc2 5.3-rc2 tip +rwk+fix Ops NUMA alloc hit 60077762.00 60387907.00 Ops NUMA alloc miss 0.00 0.00 Ops NUMA interleave hit 0.00 0.00 Ops NUMA alloc local 60077571.00 60387798.00 Ops NUMA base-page range updates 5948.00 17223.00 Ops NUMA PTE updates 5948.00 17223.00 Ops NUMA PMD updates 0.00 0.00 Ops NUMA hint faults 4639.00 14050.00 Ops NUMA hint local faults % 2073.00 6515.00 Ops NUMA hint local percent 44.69 46.37 Ops NUMA pages migrated 1528.00 4306.00 Ops AutoNUMA cost 23.27 70.45 > > > > > > > > I agree that additional patches are probably needed to improve load > > > > balance at NUMA level and I expect that this rework will make it > > > > simpler to add. > > > > I just wanted to get the output of some real use cases before defining > > > > more numa level specific conditions. Some want to spread on there numa > > > > nodes but other want to keep everything together. The preferred node > > > > and fbq_classify_group was the only sensible metrics to me when he > > > > wrote this patchset but changes can be added if they make sense. > > > > > > > > > > That's fair. While it was possible to address the case before your > > > series, it was a hatchet job. If the changelog simply notes that some > > > special casing may still be required for SD_NUMA but it's outside the > > > scope of the series, then I'd be happy. At least there is a good chance > > > then if there is follow-up work that it won't be interpreted as an > > > attempt to reintroduce hacky heuristics. > > > > > > > Would the additional comment make sense for you about work to be done > > for SD_NUMA ? > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 0ad4b21..7e4cb65 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -6960,11 +6960,34 @@ enum fbq_type { regular, remote, all }; > > * group. see update_sd_pick_busiest(). > > */ > > enum group_type { > > + /* > > + * The group has spare capacity that can be used to process more work. > > + */ > > group_has_spare = 0, > > + /* > > + * The group is fully used and the tasks don't compete for more CPU > > + * cycles. Nevetheless, some tasks might wait before running. > > + */ > > group_fully_busy, > > + /* > > + * One task doesn't fit with CPU's capacity and must be migrated on a > > + * more powerful CPU. > > + */ > > group_misfit_task, > > + /* > > + * One local CPU with higher capacity is available and task should be > > + * migrated on it instead on current CPU. > > + */ > > group_asym_packing, > > + /* > > + * The tasks affinity prevents the scheduler to balance the load across > > + * the system. > > + */ > > group_imbalanced, > > + /* > > + * The CPU is overloaded and can't provide expected CPU cycles to all > > + * tasks. > > + */ > > group_overloaded > > }; > > Looks good. > > > > > @@ -8563,7 +8586,11 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s > > > > /* > > * Try to use spare capacity of local group without overloading it or > > - * emptying busiest > > + * emptying busiest. > > + * XXX Spreading tasks across numa nodes is not always the best policy > > + * and special cares should be taken for SD_NUMA domain level before > > + * spreading the tasks. For now, load_balance() fully relies on > > + * NUMA_BALANCING and fbq_classify_group/rq to overide the decision. > > */ > > if (local->group_type == group_has_spare) { > > if (busiest->group_type > group_fully_busy) { > > Perfect. Any patch in that are can then update the comment and it > should be semi-obvious to the next reviewer that it's expected. > > Thanks Vincent. > > -- > Mel Gorman > SUSE Labs