Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750811AbWIUHhr (ORCPT ); Thu, 21 Sep 2006 03:37:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750807AbWIUHhr (ORCPT ); Thu, 21 Sep 2006 03:37:47 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:15501 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S1750811AbWIUHhq (ORCPT ); Thu, 21 Sep 2006 03:37:46 -0400 Date: Thu, 21 Sep 2006 09:29:08 +0200 From: Ingo Molnar To: Bill Huey Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , John Stultz , "Paul E. McKenney" , Dipankar Sarma , Arjan van de Ven , Esben Nielsen Subject: Re: [PATCH] move put_task_struct() reaping into a thread [Re: 2.6.18-rt1] Message-ID: <20060921072908.GA27280@elte.hu> References: <20060920141907.GA30765@elte.hu> <20060921065624.GA9841@gnuppy.monkey.org> <20060921065402.GA22089@elte.hu> <20060921071838.GA10337@gnuppy.monkey.org> <20060921071624.GA25281@elte.hu> <20060921073222.GC10337@gnuppy.monkey.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060921073222.GC10337@gnuppy.monkey.org> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -2.9 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.9 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.5 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.4998] -0.1 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1425 Lines: 29 * Bill Huey wrote: > > but it _is_ already being reaped in another thread: softirq-rcu. > > Splitting that up any further will only fragment the > > context-switching and increases cache footprint - it wont (or > > rather, shouldnt) have any functional effect. (As a sidenote, i'm > > considering the unification of all 'same default priority' softirq > > threads into a single thread per CPU, to further reduce this cost of > > 'spreadout'.) > > I overloaded another reaping thread that was doing largely similar > functionality in that it was also reaping, so I don't think it's that > bad. I did it from a cleanliness point of view with the code tree. > It's the "desched_thread" in fork.c that I'm using. It seems to be the > right thing to do. I'm sure Esben will follow up on this. the reason why i added desched_thread was not because it's "more right" to do this from a separate context, but simply because the resource freed by it is not being freed via RCU by the upstream kernel. If that resource (mm_struct) were freed by RCU we'd have its rt-friendly reapdown "for free" and no desched_thread would be needed at all. Ingo - 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/