Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262600AbVCVKfV (ORCPT ); Tue, 22 Mar 2005 05:35:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262611AbVCVKfU (ORCPT ); Tue, 22 Mar 2005 05:35:20 -0500 Received: from smtp.Lynuxworks.com ([207.21.185.24]:38664 "EHLO smtp.lynuxworks.com") by vger.kernel.org with ESMTP id S262600AbVCVKfP (ORCPT ); Tue, 22 Mar 2005 05:35:15 -0500 Date: Tue, 22 Mar 2005 02:34:49 -0800 To: Bill Huey Cc: Esben Nielsen , Ingo Molnar , "Paul E. McKenney" , dipankar@in.ibm.com, shemminger@osdl.org, akpm@osdl.org, torvalds@osdl.org, rusty@au1.ibm.com, tgall@us.ibm.com, jim.houston@comcast.net, manfred@colorfullife.com, gh@us.ibm.com, linux-kernel@vger.kernel.org Subject: Re: Real-Time Preemption and RCU Message-ID: <20050322103449.GA581@nietzsche.lynx.com> References: <20050318160229.GC25485@elte.hu> <20050322100446.GA448@nietzsche.lynx.com> <20050322101727.GB448@nietzsche.lynx.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050322101727.GB448@nietzsche.lynx.com> User-Agent: Mutt/1.5.6+20040907i From: Bill Huey (hui) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1161 Lines: 25 On Tue, Mar 22, 2005 at 02:17:27AM -0800, Bill Huey wrote: > > A notion of priority across a quiescience operation is crazy anyways[-,-] so > > it would be safe just to use to the old rwlock-semaphore "in place" without > > any changes or priorty handling add[i]tions. The RCU algorithm is only concerned > > with what is basically a coarse data guard and it isn't time or priority > > critical. > > A little jitter in a quiescence operation isn't going to hurt things right ?. The only thing that I can think of that can go wrong here is what kind of effect it would have on the thread write blocking against a bunch of RCU readers. It could introduce a chain of delays into, say, a timer event and might cause problems/side-effects for other things being processed. RCU processing might have to decoupled processed by a different thread to avoid some of that latency weirdness. What do you folks think ? bill - 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/