Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755193Ab0FSIlZ (ORCPT ); Sat, 19 Jun 2010 04:41:25 -0400 Received: from hera.kernel.org ([140.211.167.34]:46534 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755027Ab0FSIlX (ORCPT ); Sat, 19 Jun 2010 04:41:23 -0400 Message-ID: <4C1C8263.9040404@kernel.org> Date: Sat, 19 Jun 2010 10:40:03 +0200 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.1.10) Gecko/20100512 Thunderbird/3.0.5 MIME-Version: 1.0 To: Andi Kleen CC: Andy Walls , Daniel Walker , mingo@elte.hu, linux-kernel@vger.kernel.org, jeff@garzik.org, akpm@linux-foundation.org, rusty@rustcorp.com.au, cl@linux-foundation.org, dhowells@redhat.com, arjan@linux.intel.com, johannes@sipsolutions.net, oleg@redhat.com, axboe@kernel.dk Subject: Re: Overview of concurrency managed workqueue References: <1276551467-21246-1-git-send-email-tj@kernel.org> <4C17C598.7070303@kernel.org> <1276631037.6432.9.camel@c-dwalke-linux.qualcomm.com> <4C18BF40.40607@kernel.org> <1276694825.9309.12.camel@m0nster> <4C18D1FD.9060804@kernel.org> <1276695665.9309.17.camel@m0nster> <4C18D574.1040903@kernel.org> <1276697146.9309.27.camel@m0nster> <1276776066.2461.15.camel@localhost> <87vd9fo1sk.fsf@basil.nowhere.org> In-Reply-To: <87vd9fo1sk.fsf@basil.nowhere.org> X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Sat, 19 Jun 2010 08:40:05 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1327 Lines: 38 On 06/19/2010 10:38 AM, Andi Kleen wrote: > Andy Walls writes: >> >> I'm going to agree with Tejun, that tweaking worker thread priorities >> seems like an odd thing, since they are meant to handle deferable >> actions - things that can be put off until later. > >> If one needs to support Real Time deadlines on deferable actions, >> wouldn't using dedicated kernel threads be more deterministic? >> Would the user ever up the priority for a workqueue other than a >> single-threaded workqueue? > > One exceptional case here are things like high priority error handling > which is rare. > > For example you get an MCE that tells you some of your > memory got corrupted and you should handle it ASAP. > Better give it high priority then. > > But it's still a rare event so you don't want dedicated > threads hanging around for it all time > (that's what we currently have and it causes all sorts > of problems) > > So yes I think having a priority mechanism for work items > is useful. Wouldn't that be better served by cpu_stop? Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/