Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750802AbWHKIRQ (ORCPT ); Fri, 11 Aug 2006 04:17:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750807AbWHKIRP (ORCPT ); Fri, 11 Aug 2006 04:17:15 -0400 Received: from mx01.stofanet.dk ([212.10.10.11]:56539 "EHLO mx01.stofanet.dk") by vger.kernel.org with ESMTP id S1750802AbWHKIRN (ORCPT ); Fri, 11 Aug 2006 04:17:13 -0400 Date: Fri, 11 Aug 2006 10:16:56 +0200 (CEST) From: Esben Nielsen X-X-Sender: simlo@frodo.shire To: Bill Huey cc: Esben Nielsen , Steven Rostedt , Robert Crocombe , linux-kernel@vger.kernel.org, Ingo Molnar , Thomas Gleixner , Darren Hart Subject: Re: [Patch] restore the RCU callback to defer put_task_struct() Re: Problems with 2.6.17-rt8 In-Reply-To: <20060811010646.GA24434@gnuppy.monkey.org> Message-ID: References: <1154541079.25723.8.camel@localhost.localdomain> <1154615261.32264.6.camel@localhost.localdomain> <20060808025615.GA20364@gnuppy.monkey.org> <20060808030524.GA20530@gnuppy.monkey.org> <20060810021835.GB12769@gnuppy.monkey.org> <20060811010646.GA24434@gnuppy.monkey.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1616 Lines: 44 On Thu, 10 Aug 2006, Bill Huey wrote: > On Wed, Aug 09, 2006 at 07:18:35PM -0700, Bill Huey wrote: >> On Thu, Aug 10, 2006 at 12:05:57AM +0200, Esben Nielsen wrote: >>> I had a long discussion with Paul McKenney about this. I opposed the patch >>> from a latency point of view: Suddenly a high-priority RT task could be >>> made into releasing a task_struct. It would be better for latencies to >>> defer it to a low priority task. >>> >>> The conclusion we ended up with was that it is not a job for the RCU >>> system, but it ought to be deferred to some other low priority task to >>> free the task_struct. >> >> I agree. It's just hack to get it not to crash at this time. It really >> should be done in another facility or utilizing another threading context. > > Esben and company, > > This is the second round of getting rid of the locking problems with free_task() > > This extends the mmdrop logic with desched_thread() to also handle free_task() > requests as well. I believe this address your concerns and I'm open to review > of this patch. > > Patch included: > > bill > > Without applying the patch and only skimming it it looks like what Paul and I concluded :-) But is there really no generic way of defering this kind of thing? It looks like a hell of a lot work where a kind of "message" infrastructure could have solved it in a few lines. Esben - 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/