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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 AEB2BCA9EC5 for ; Wed, 30 Oct 2019 17:29:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 788772087E for ; Wed, 30 Oct 2019 17:29:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dVDrUgZF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727334AbfJ3R3b (ORCPT ); Wed, 30 Oct 2019 13:29:31 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:40208 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726488AbfJ3R3a (ORCPT ); Wed, 30 Oct 2019 13:29:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1572456569; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=zA6i4fJUFRWIbj335/B8QHiHn0dUPzjeEPZBp4eEnG8=; b=dVDrUgZFGoM4MPbcTAMBmeyp0nxeJS5y8C11wK1PwFuO3vr3Nij1fx57v+BGYS34FEN5rN 1fdptVWNSyoAkR6Zj5/j8b7ROiQ/j0wphRYf744n9chGk8V1CEASAAEAl7NEssm4/8FFIA Z7xw/G2lAJ4kE/GZuqxtqsGeJyi2WvU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-174-FwEAjuNyPbe-r_yj9282kA-1; Wed, 30 Oct 2019 13:29:25 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CDEAF1005500; Wed, 30 Oct 2019 17:29:23 +0000 (UTC) Received: from pauld.bos.csb (dhcp-17-51.bos.redhat.com [10.18.17.51]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6FA8B5D6D4; Wed, 30 Oct 2019 17:29:22 +0000 (UTC) Date: Wed, 30 Oct 2019 13:29:20 -0400 From: Phil Auld To: Valentin Schneider Cc: Dietmar Eggemann , Vincent Guittot , Ingo Molnar , Mel Gorman , linux-kernel , Ingo Molnar , Peter Zijlstra , Srikar Dronamraju , Quentin Perret , Morten Rasmussen , Hillf Danton , Parth Shah , Rik van Riel Subject: Re: [PATCH v4 00/10] sched/fair: rework the CFS load balance Message-ID: <20191030172920.GH1686@pauld.bos.csb> References: <20191024123844.GB2708@pauld.bos.csb> <20191024134650.GD2708@pauld.bos.csb> <20191025133325.GA2421@pauld.bos.csb> <20191030143937.GC1686@pauld.bos.csb> <564ca629-5c34-dbd1-8e64-2da6910b18a3@arm.com> <20191030171914.GF1686@pauld.bos.csb> <4c52d81f-4b3b-d7e8-c124-b90b4584a6d3@arm.com> MIME-Version: 1.0 In-Reply-To: <4c52d81f-4b3b-d7e8-c124-b90b4584a6d3@arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: FwEAjuNyPbe-r_yj9282kA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 30, 2019 at 06:25:09PM +0100 Valentin Schneider wrote: > On 30/10/2019 18:19, Phil Auld wrote: > >> Well from the code nobody but us (asymmetric capacity systems) set > >> SD_BALANCE_WAKE. I was however curious if there were some folks who se= t it > >> with out of tree code for some reason. > >> > >> As Dietmar said, not having SD_BALANCE_WAKE means you'll never go thro= ugh > >> the slow path on wakeups, because there is no domain with SD_BALANCE_W= AKE for > >> the domain loop to find. Depending on your topology you most likely wi= ll > >> go through it on fork or exec though. > >> > >> IOW wake_wide() is not really widening the wakeup scan on wakeups usin= g > >> mainline topology code (disregarding asymmetric capacity systems), whi= ch > >> sounds a bit... off. > >=20 > > Thanks. It's not currently set. I'll set it and re-run to see if it mak= es > > a difference.=20 > >=20 >=20 > Note that it might do more harm than good, it's not set in the default > topology because it's too aggressive, see=20 >=20 > 182a85f8a119 ("sched: Disable wakeup balancing") >=20 Heh, yeah... even as it's running I can see that this killing it :) > >=20 > > However, I'm not sure why it would be making a difference for only the = cgroup > > case. If this is causing issues I'd expect it to effect both runs.=20 > >=20 > > In general I think these threads want to wake up the last cpu they were= on. > > And given there are fewer cpu bound tasks that CPUs that wake cpu shoul= d, > > more often than not, be idle.=20 > >=20 > >=20 > > Cheers, > > Phil > >=20 > >=20 > >=20 --=20