From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261822AbVCLBWf (ORCPT ); Fri, 11 Mar 2005 20:22:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261828AbVCLBWf (ORCPT ); Fri, 11 Mar 2005 20:22:35 -0500 Received: from fire.osdl.org ([65.172.181.4]:24196 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S261822AbVCLBWa (ORCPT ); Fri, 11 Mar 2005 20:22:30 -0500 Date: Fri, 11 Mar 2005 17:22:28 -0800 From: Andrew Morton To: Christoph Lameter Cc: linux-kernel@vger.kernel.org, linux-mm@vger.kernel.org, torvalds@osdl.org Subject: Re: [PATCH] Prefaulting Message-Id: <20050311172228.773cf03d.akpm@osdl.org> In-Reply-To: References: X-Mailer: Sylpheed version 1.0.0 (GTK+ 1.2.10; i386-vine-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Christoph Lameter wrote: > > This patch allows to aggregate multiple page faults into a single one. It > does that by detecting that an application generates a sequence of page > faults. > > ... > Results that show the impact of this patch are available at > http://oss.sgi.com/projects/page_fault_performance/ There are a lot of numbers there. Was there an executive summary? >>From a quick peek it seems that the patch makes negligible difference for a kernel compilation when prefaulting 1-2 pages and slows the workload down quite a lot when prefaulting up to 16 pages. And for the uniprocessor "200 Megabyte allocation without prezeroing. Single thread." workload it appears that the prefault patch slowed it down by 4x. Am I misreading the results? If not, it's a bit disappointing.