From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267750AbUHPPYc (ORCPT ); Mon, 16 Aug 2004 11:24:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267711AbUHPPU3 (ORCPT ); Mon, 16 Aug 2004 11:20:29 -0400 Received: from omx3-ext.sgi.com ([192.48.171.20]:49586 "EHLO omx3.sgi.com") by vger.kernel.org with ESMTP id S267713AbUHPPTG (ORCPT ); Mon, 16 Aug 2004 11:19:06 -0400 Date: Mon, 16 Aug 2004 08:18:11 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Ray Bryant cc: "David S. Miller" , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: page fault fastpath: Increasing SMP scalability by introducing pte locks? In-Reply-To: <41205BAA.9030800@sgi.com> Message-ID: References: <20040815130919.44769735.davem@redhat.com> <20040815165827.0c0c8844.davem@redhat.com> <20040815185644.24ecb247.davem@redhat.com> <41205BAA.9030800@sgi.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 16 Aug 2004, Ray Bryant wrote: > Something else to worry about here is mm->rss. Previously, this was updated > only with the page_table_lock held, so concurrent increments were not a > problem. rss may need to converted be an atomic_t if you use pte_locks. > It may be that an approximate value for rss is good enough, but I'm not sure > how to bound the error that could be introduced by a couple of hundred > processers handling page faults in parallel and updating rss without locking > it or making it an atomic_t. Correct. There are a number of issues that may have to be addressed but first we need to agree on a general idea how to proceed.