From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752868AbbDAPqw (ORCPT ); Wed, 1 Apr 2015 11:46:52 -0400 Received: from mail-qg0-f43.google.com ([209.85.192.43]:36170 "EHLO mail-qg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752576AbbDAPql (ORCPT ); Wed, 1 Apr 2015 11:46:41 -0400 Date: Wed, 1 Apr 2015 11:46:37 -0400 From: Tejun Heo To: Peter Zijlstra Cc: cmetcalf@ezchip.com, Frederic Weisbecker , "Paul E. McKenney" , "Rafael J. Wysocki" , Martin Schwidefsky , linux-kernel@vger.kernel.org Subject: Re: [PATCH] workqueue: avoid nohz_full cores Message-ID: <20150401154637.GN9974@htj.duckdns.org> References: <1427829959-3023-1-git-send-email-cmetcalf@ezchip.com> <20150331193745.GH9974@htj.duckdns.org> <20150401075607.GW27490@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150401075607.GW27490@worktop.programming.kicks-ass.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 01, 2015 at 09:56:07AM +0200, Peter Zijlstra wrote: > > The problem with this is that workqueue currently doesn't distinguish > > why work items are queued on per-cpu workqueues. It can't tell > > whether being bound to local CPU is for correctness or optimization > > and thus can't break local execution guarantee for anybody. We need > > to hunt down all the ones which depend on local execution and annotate > > them with explicit queue_work_on() before being able to do this. > > This is moot on unbound workqueues, they can run wherever so it can > never be a correctness thing, right? The posted patch applies to both unbound and per-cpu workqueues. There's a more comprehensive patchset currently being worked on by Lai for unbound workqueues. Thanks. -- tejun