Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752814AbbEHNNb (ORCPT ); Fri, 8 May 2015 09:13:31 -0400 Received: from mga03.intel.com ([134.134.136.65]:54699 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751469AbbEHNN3 (ORCPT ); Fri, 8 May 2015 09:13:29 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,391,1427785200"; d="scan'208";a="568358442" Message-ID: <1431090801.1418.87.camel@sauron.fi.intel.com> Subject: Re: [PATCH] numa,sched: only consider less busy nodes as numa balancing destination From: Artem Bityutskiy Reply-To: dedekind1@gmail.com To: Rik van Riel Cc: linux-kernel@vger.kernel.org, mgorman@suse.de, peterz@infradead.org, jhladky@redhat.com Date: Fri, 08 May 2015 16:13:21 +0300 In-Reply-To: <20150506114128.0c846a37@cuia.bos.redhat.com> References: <1430908530.7444.145.camel@sauron.fi.intel.com> <20150506114128.0c846a37@cuia.bos.redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4 (3.10.4-4.fc20) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1777 Lines: 50 On Wed, 2015-05-06 at 11:41 -0400, Rik van Riel wrote: > On Wed, 06 May 2015 13:35:30 +0300 > Artem Bityutskiy wrote: > > > we observe a tremendous regression between kernel version 3.16 and 3.17 > > (and up), and I've bisected it to this commit: > > > > a43455a sched/numa: Ensure task_numa_migrate() checks the preferred node > > Artem, Jirka, does this patch fix (or at least improve) the issues you > have been seeing? Does it introduce any new regressions? Hi Rik, first of all thanks for your help! I've tried this patch and it has very small effect. I've also ran the benchmark with auto-NUMA disabled too, which is useful, I think. I used the tip of Linuses tree (v4.1-rc2+). Kernel Avg response time, ms ------------------------------------------------------ Vanilla 1481 Patched 1240 Reverted 256 Disabled 309 Vanilla: pristine v4.1-rc2+ Patched: Vanilla + this patch Reverted: Vanilla + a revert of a43455a Disabled: Vanilla and auto-NUMA disabled via procfs I ran the benchmark for 1 hour for every configuration this time. I cannot say for sure the deviation right now, but I think it is tens of milliseconds, so disabled vs reverted _may_ be within the error range, but I need to do more experiments. So this patch dropped the average Web server response time dropped from about 1.4 seconds to about 1.2 seconds, which isn't a bad improvement, but it is far less than what we get when reverting that patch. Artem. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/