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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 7F6C2C433E0 for ; Thu, 14 Jan 2021 09:13:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3AA7123A01 for ; Thu, 14 Jan 2021 09:13:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728057AbhANJNS (ORCPT ); Thu, 14 Jan 2021 04:13:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727244AbhANJNP (ORCPT ); Thu, 14 Jan 2021 04:13:15 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 73208C061795 for ; Thu, 14 Jan 2021 01:12:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=/5Zz0p2oJ5TA6sIaD5hjXMpw1Dava3EZAquKucaVYXA=; b=daxvThX9yb1jhpfOHQo81F3XDc UXko2aQGZpWZkBR9htUUH14eQiftil+FcDu2j31Y3oqTNHxfPKAxyqu8duyCjRrosTDtSSIaiXcud NgJYIJ8jlhCztI+rTV0Bk5gbtBZd/vU4BnGGnVBurm2F5FIqi1m6xZeyM+TB4ZEbbafklwdUigQkM TqVdLawaIIrHFD6qMGZ8AbQhNqIlvPTpsrrLMj//E/woYqerkjxZruE/LTuKWKdHf+eDmvNAQeW/m 0tAxJCBu0NqVz3yFld0Y+8O1B7z1hDvQRDxszvzcFIOhKtau5WRfN6i5COI9c9kYoEEk+tEqbu4HO Qp4natuQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1kzyfX-007Mpo-Gw; Thu, 14 Jan 2021 09:12:02 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id CEB3F301324; Thu, 14 Jan 2021 10:11:48 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C0E042C3CFB7B; Thu, 14 Jan 2021 10:11:48 +0100 (CET) Date: Thu, 14 Jan 2021 10:11:48 +0100 From: Peter Zijlstra To: "Zhang, Qiang" Cc: "linux-kernel@vger.kernel.org" Subject: Re: Question on workqueue: Manually break affinity on hotplug Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 14, 2021 at 08:03:23AM +0000, Zhang, Qiang wrote: > Hello Peter > > Excuse me, I have some questions for you, about a description of this change: > > ''Don't rely on the scheduler to force break affinity for us -- it will > stop doing that for per-cpu-kthreads." > > this mean when cpuhotplug, scheduler do not change affinity for per-cpu-kthread's task, if we not active setting affinity? > but if per-cpu-kthread's task is not run state, when wake up, will reset it's affinity, this is done automatically. > > or is it, this place modified to fit the new one hotplug mechanism which > ("sched/hotplug: Consolidate task migration on CPU unplug")? https://lkml.kernel.org/r/20201214155457.3430-1-jiangshanlai@gmail.com https://lkml.kernel.org/r/20201218170919.2950-1-jiangshanlai@gmail.com https://lkml.kernel.org/r/20201226025117.2770-1-jiangshanlai@gmail.com https://lkml.kernel.org/r/20210111152638.2417-1-jiangshanlai@gmail.com https://lkml.kernel.org/r/20210112144344.850850975@infradead.org