Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965455AbWI0JRJ (ORCPT ); Wed, 27 Sep 2006 05:17:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965465AbWI0JRJ (ORCPT ); Wed, 27 Sep 2006 05:17:09 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:37024 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S965455AbWI0JRG (ORCPT ); Wed, 27 Sep 2006 05:17:06 -0400 Date: Wed, 27 Sep 2006 11:08:45 +0200 From: Ingo Molnar To: "Eric W. Biederman" Cc: Bill Huey , linux-kernel@vger.kernel.org, Thomas Gleixner , John Stultz , "Paul E. McKenney" , Dipankar Sarma , Arjan van de Ven Subject: Re: [PATCH] move put_task_struct() reaping into a thread [Re: 2.6.18-rt1] Message-ID: <20060927090845.GB20395@elte.hu> References: <20060920141907.GA30765@elte.hu> <20060921065624.GA9841@gnuppy.monkey.org> <20060927050856.GA16140@gnuppy.monkey.org> <20060927063415.GB16140@gnuppy.monkey.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: 0.5000] -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: 912 Lines: 21 * Eric W. Biederman wrote: > About the rcu removal discussion I heard it was more the possibility > was suggested because the downside was significant, and normal locks > were more deterministic. The emphasis was that call_rcu could be a > problem and that something needs to happen to fix that. RCU is really mostly used as a garbage-collection scheme, and hence its latency, while it can be practically problematic in some cases, never is directly visible in terms of application or kernel behavior. the same is in this case: the call_rcu() use is for gathering totally unused task structs. There should be no side-effects. 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/