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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81D0FC433F5 for ; Tue, 26 Oct 2021 10:42:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A01060E74 for ; Tue, 26 Oct 2021 10:42:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234846AbhJZKo3 (ORCPT ); Tue, 26 Oct 2021 06:44:29 -0400 Received: from mout.gmx.net ([212.227.17.22]:39529 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234610AbhJZKo1 (ORCPT ); Tue, 26 Oct 2021 06:44:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1635244899; bh=14D6tPu6/w2h5fXF3oe5B5m7qR91fUuAunOnONVlQy4=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To:References; b=kKGSHttxWvucd27+sltFv4pMJ/ljfSIUQOHt6jiE1Oo6LeiZwqiVdq527BZFXtRQo DggAUQaZjAaU1W8t0VdCo+DLIvbtEHojAt68vVcB/zKvRemr28vhp7BweXotzFLLs6 KVTHyoZmqt4Qnput4qlobnHiMk+Ufyg4N49BgKYk= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from homer.fritz.box ([185.146.49.114]) by mail.gmx.net (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1N8GMq-1mjWyJ0l0q-014GmI; Tue, 26 Oct 2021 12:41:39 +0200 Message-ID: Subject: Re: [PATCH 1/2] sched/fair: Couple wakee flips with heavy wakers From: Mike Galbraith To: Mel Gorman Cc: Peter Zijlstra , Ingo Molnar , Vincent Guittot , Valentin Schneider , Aubrey Li , Barry Song , Srikar Dronamraju , LKML Date: Tue, 26 Oct 2021 12:41:36 +0200 In-Reply-To: <4105fd08f84c60698b38efcb4d22e999de187d6e.camel@gmx.de> References: <20211021145603.5313-1-mgorman@techsingularity.net> <20211021145603.5313-2-mgorman@techsingularity.net> <37d8c167df66a1ead16b699115548ca376494c0c.camel@gmx.de> <20211022110534.GJ3959@techsingularity.net> <496d495b290ac69fed75d02ab5915a7871243321.camel@gmx.de> <20211026081817.GM3959@techsingularity.net> <4105fd08f84c60698b38efcb4d22e999de187d6e.camel@gmx.de> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:+EcfWhzAuOffxc6Ta5wfgEYmzyUCWgibKWaOXJdc5oTpafHOjl9 jAQISlBQIxQmwqrHutWFzPUCwMFlZvnqjyHc5HXtWe20OaqksRihJPV851M48a639Cw4XCV Et5kcataonB30hMlVYgPkJyoRGaKMYunc5EUQ1t2bV/1BuCavuYGyHT2Q1I0ivYy4fMpt0i T4xbZevnp+h/MOfa8gg9w== X-UI-Out-Filterresults: notjunk:1;V03:K0:MNrjrNhalXE=:Vtfr79cBl1bZxmqayMgOZU eSNkzRjRqonACYfq5Id9s/3IM2NYE/6Hz4iUp0bgGNf2BRMiv6TM8QaBrzeZqee9PkdhIrssV iM90RAP7Sl1lj9qME0tbWOjjaZr/FlmUSrf6/aaQR7+svo4ro2HmxTzLmGaE4M8D+iPOy90jH bmmEul09tRm1/6/SpjUmgz6vPA3PVtQ86I6quGKToafzZqrhs5eW8iN0cr0HW274bkmIMzre9 yVllH8RH8pKzwkGoRhWPfkbqexRsvuf6FLS/1S/++z/wNzhX6YIJ8RG3ua1eEWnw2KiyUpKNM VKS4tYYwQv+MO0nlvoyNOEynW9iKbwniubMAnQwJoi5pY6kkSc8HVyVbh27//3w+14sIYQ1Qc u2uGYIg4On9H5unhyhh3nYibTUc1r03tU5bxLOt0Sc1pypxnO2E3KQ/M8SJC9oOz2mb68VnsZ UyWAKaA0bpZ7x5HG6mn7dUquTnY5O0KrjJD3d1eHfNw0G6Y3sOMQsiCkvL2cTAyB8zH3Tm7tk vCYMqq8nMbPCHCM4sooBMH6CW1BC91IE7gLurL+XUL1zz5JoNxG/3/VNagUCq7g4NIAZN7YgN d5Rzkrr3KL1rpfR8iJE27PILzzO0cnSRKuMviEjPemm4tXjAmkTiISpZ8pxj/eJgJ6sPeKAMl 7uzEHO3Dn9/YELpQ+d+F+PyY5r21AQeOhGqwfJTWMZoZb1fEdFqKdLRGqkqcEpfNrRLRV2BNl i4Zq4vRYjtsFp7Tn+wGWdHpuWk6UAFRH5k1xbV+MiXhM1eE+11baKx+8zydH+ivqqGs8DEP+9 7fNpU1Vrljv48a0cJPM3xjBbjKNUQ0x1H6YR8tDCS055u9lYodBo0R+/cbw2sE9aFvuMN6itw e1v4YzNfW6wd05OeDO+Nxs2ptOmhEvJB57/ZveIo7hyX7lUshCOd68fz7X+JaYa8ZaGFaRG9n /FBf1fph85Ewq4MGfHfkErPsf9/O1nvA4oBuyefmlYuY0agSUKavUcU1iKTXo10y62Cbcu5iO UFSQI0rLWdlNNlz+/MBsElvCxie1AUYH7qojuQa8Exy/EXlbEDkLp1Wd1d0fRxeMoTscnJs2/ 0TP+P7PW3ipDoc= Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2021-10-26 at 12:15 +0200, Mike Galbraith wrote: > ... Well now, that interruption didn't go as planned. The briefer edit would have been preferred, but you get the drift, so moving on... > > > It benefiting NUMA box > > > hackbench is a valid indicator, but one that is IMO too disconnected > > > from the real world to carry much weight. > > > > > > > I think if it's not shown to be harmful to a realistic workload but he= lps > > an overloaded example then it should be ok. While excessive overload i= s > > rare in a realistic workload, it does happen. There are a few workload= s > > I've seen bugs for that were triggered when an excessive number of wor= ker > > threads get spawned and compete for CPU access which in turns leads mo= re > > worker threads get spawned. There are application workarounds for this > > corner case but it still triggers bugs. > wake_wide()'s proper test environment is NUMA, not a desktop box, so patchlet has yet to meet a real world load that qualifies as such. That it could detect the test load doing nutty stuff like waking a thread pool three times the size of the box is all well and good, but not the point. $.02 WRT poor abused hackbench: if it happens to benefit that's fine, but I don't think it should ever be considered change validation. It's a useful tool, but the common massive overload use is just nuts IMO. -Mike