From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262088AbVF0Qh1 (ORCPT ); Mon, 27 Jun 2005 12:37:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262098AbVF0PCT (ORCPT ); Mon, 27 Jun 2005 11:02:19 -0400 Received: from dvhart.com ([64.146.134.43]:49074 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id S261649AbVF0OI1 (ORCPT ); Mon, 27 Jun 2005 10:08:27 -0400 Date: Mon, 27 Jun 2005 07:08:26 -0700 From: "Martin J. Bligh" Reply-To: "Martin J. Bligh" To: Andrew Morton , Nick Piggin Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [rfc] lockless pagecache Message-ID: <95150000.1119881306@[10.10.2.4]> In-Reply-To: <20050627004624.53f0415e.akpm@osdl.org> References: <42BF9CD1.2030102@yahoo.com.au> <20050627004624.53f0415e.akpm@osdl.org> X-Mailer: Mulberry/2.2.1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --Andrew Morton wrote (on Monday, June 27, 2005 00:46:24 -0700): > Nick Piggin wrote: >> >> First I'll put up some numbers to get you interested - of a 64-way Altix >> with 64 processes each read-faulting in their own 512MB part of a 32GB >> file that is preloaded in pagecache (with the proper NUMA memory >> allocation). > > I bet you can get a 5x to 10x reduction in ->tree_lock traffic by doing > 16-page faultahead. Maybe true, but when we last tried that, faultahead sucked for performance in a more general sense. All the extra setup and teardown cost for unnecessary PTEs kills you, even if it's only 4 pages or so. M.