Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756657AbXJAWZE (ORCPT ); Mon, 1 Oct 2007 18:25:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752127AbXJAWYz (ORCPT ); Mon, 1 Oct 2007 18:24:55 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:56915 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751691AbXJAWYx (ORCPT ); Mon, 1 Oct 2007 18:24:53 -0400 Date: Mon, 1 Oct 2007 15:24:49 -0700 From: "Paul E. McKenney" To: Davide Libenzi Cc: Oleg Nesterov , Linux Kernel Mailing List , linux-rt-users@vger.kernel.org, Ingo Molnar , Andrew Morton , dipankar@in.ibm.com, josht@linux.vnet.ibm.com, tytso@us.ibm.com, dvhltc@us.ibm.com, tglx@linutronix.de, a.p.zijlstra@chello.nl, bunk@kernel.org, ego@in.ibm.com, srostedt@redhat.com Subject: Re: [PATCH RFC 3/9] RCU: Preemptible RCU Message-ID: <20071001222449.GA11367@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20070926151351.GA328@tv-sign.ru> <20070927154652.GE16652@linux.vnet.ibm.com> <20070928144714.GA397@tv-sign.ru> <20070928185759.GC9153@linux.vnet.ibm.com> <20070930163102.GA374@tv-sign.ru> <20071001013739.GB12494@linux.vnet.ibm.com> <20071001192136.GC29100@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 984 Lines: 21 On Mon, Oct 01, 2007 at 03:09:16PM -0700, Davide Libenzi wrote: > On Mon, 1 Oct 2007, Paul E. McKenney wrote: > > > That would indeed be one approach that CPU designers could take to > > avoid being careless or sadistic. ;-) > > That'd be the easier (unique maybe) approach too for them, from an silicon > complexity POV. Distinguishing between different CPUs stores once inside a > shared store buffer, would require tagging them in some way. That'd defeat > most of the pros of having a shared store buffer ;) Tagging requires but one bit per entry. Depends on the workload -- if lots of barriers, bursty stores and little sharing, tagging might win. If lots of sharing, then your suggested approach might win. Thanx, Paul - 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/