From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751517AbWBVX4N (ORCPT ); Wed, 22 Feb 2006 18:56:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751559AbWBVX4M (ORCPT ); Wed, 22 Feb 2006 18:56:12 -0500 Received: from mx2.suse.de ([195.135.220.15]:15794 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S1751517AbWBVX4L (ORCPT ); Wed, 22 Feb 2006 18:56:11 -0500 From: Chris Mason To: Dimitri Sivanich Subject: Re: [PATCH] Enable remote RCU callback processing on SMP systems Date: Wed, 22 Feb 2006 18:56:05 -0500 User-Agent: KMail/1.9.1 Cc: Andrew Morton , linux-kernel , "Paul E. McKenney" , Dipankar Sarma , okir@suse.de References: <20060206145137.GA30059@sgi.com> <200602221523.23739.mason@suse.de> <20060222220037.GC3734@sgi.com> In-Reply-To: <20060222220037.GC3734@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200602221856.07262.mason@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 22 February 2006 17:00, Dimitri Sivanich wrote: > On Wed, Feb 22, 2006 at 03:23:22PM -0500, Chris Mason wrote: > > Aside from the possible race we talked about in __rcu_process_callbacks, > > I don't have huge objections here. But if the underlying problem is the > > cost of kmem_cache_free, would it be better to limit that instead of > > trying to push the latency around to specific cpus? > > The current problem is the cost of kmem_cache_free. What this > patch will do (versus limiting the cost of kmem_cache_free, if > that's at all possible) is to protect the cpus configured as > such against other costly sections of code that may be lurking > or that might be added in the future. Right, but I'm suggesting that we might want to fix kmem_cache_free as well. I think your patch has value even with kmem_cache_free fixed. Given that the high cost parts of kmem_cache_free seem to be numa specific, fixing it seems like a good idea in general. -chris