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=-1.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS 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 2608BC433F4 for ; Tue, 18 Sep 2018 13:54:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA9582086B for ; Tue, 18 Sep 2018 13:54:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.de header.i=@amazon.de header.b="dHK1ZXDM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BA9582086B Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=amazon.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729800AbeIRT04 (ORCPT ); Tue, 18 Sep 2018 15:26:56 -0400 Received: from smtp-fw-6002.amazon.com ([52.95.49.90]:41090 "EHLO smtp-fw-6002.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727846AbeIRT0z (ORCPT ); Tue, 18 Sep 2018 15:26:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.de; i=@amazon.de; q=dns/txt; s=amazon201209; t=1537278852; x=1568814852; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=3PR+VbrDCzNid6wVZkf5NCEEC5jrBB6e77Qbjn32Q4A=; b=dHK1ZXDMWaOnYOWATIPosKpAvpL4nxSHGuXsAaGR6hM4TtsEhI7Cr9mm 7XYfnQGlVAO54cfTPOg6rePkQaW4afi2JSZS0ZSmw2aFvkH9Dj2X2TvOV qkyxmMDjrmSIRp0aZzyJ47UI5JFgANHH3TO+xvIsHZl72bYKQ1T5hkfnv s=; X-IronPort-AV: E=Sophos;i="5.53,389,1531785600"; d="scan'208";a="362890027" Received: from iad6-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-2b-4ff6265a.us-west-2.amazon.com) ([10.124.125.6]) by smtp-border-fw-out-6002.iad6.amazon.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 18 Sep 2018 13:54:10 +0000 Received: from u7588a65da6b65f.ant.amazon.com (pdx2-ws-svc-lb17-vlan2.amazon.com [10.247.140.66]) by email-inbound-relay-2b-4ff6265a.us-west-2.amazon.com (8.14.7/8.14.7) with ESMTP id w8IDs6eE007894 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL); Tue, 18 Sep 2018 13:54:08 GMT Received: from u7588a65da6b65f.ant.amazon.com (localhost [127.0.0.1]) by u7588a65da6b65f.ant.amazon.com (8.15.2/8.15.2/Debian-3) with ESMTP id w8IDs4Xs006243; Tue, 18 Sep 2018 15:54:04 +0200 Subject: Re: Task group cleanups and optimizations (was: Re: [RFC 00/60] Coscheduling for Linux) To: Peter Zijlstra Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Paul Turner , Vincent Guittot , Morten Rasmussen , Tim Chen , Rik van Riel References: <20180907214047.26914-1-jschoenh@amazon.de> <20180914111251.GC24106@hirez.programming.kicks-ass.net> <1d86f497-9fef-0b19-50d6-d46ef1c0bffa@amazon.de> <282230fe-b8de-01f9-c19b-6070717ba5f8@amazon.de> <20180917094844.GR24124@hirez.programming.kicks-ass.net> <08b930d9-7ffe-7df3-ab35-e7b58073e489@amazon.de> <20180918133805.GN24106@hirez.programming.kicks-ass.net> From: "=?UTF-8?Q?Jan_H._Sch=c3=b6nherr?=" Openpgp: preference=signencrypt Message-ID: <3d49801b-01cd-579b-f731-d6ca7aed985d@amazon.de> Date: Tue, 18 Sep 2018 15:54:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180918133805.GN24106@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/18/2018 03:38 PM, Peter Zijlstra wrote: > On Tue, Sep 18, 2018 at 03:22:13PM +0200, Jan H. Schönherr wrote: >> AFAIK, changing the affinity of a cpuset overwrites the individual affinities of tasks >> within them. Thus, it shouldn't be an issue. > > No, it only shrinks the set. Also nothing stops you calling > sched_setaffinity() once you're inside the cpuset. The only contraint is > that your mask is a subset of the cpuset mask. I meant setting the affinity of the cpuset *after* setting an individual affinity. Like this: # mkdir /sys/fs/cgroup/cpuset/test # cat /sys/fs/cgroup/cpuset/cpuset.mems > /sys/fs/cgroup/cpuset/test/cpuset.mems # cat /sys/fs/cgroup/cpuset/cpuset.cpus > /sys/fs/cgroup/cpuset/test/cpuset.cpus # echo $$ > /sys/fs/cgroup/cpuset/test/tasks # taskset -c -p 0 $$ pid 4745's current affinity list: 0-3 pid 4745's new affinity list: 0 # echo "0-1" > /sys/fs/cgroup/cpuset/test/cpuset.cpus # taskset -c -p $$ pid 4745's current affinity list: 0,1 # The individual affinity of $$ is lost, despite it being a subset.