From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 21 Feb 2003 02:09:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 21 Feb 2003 02:09:26 -0500 Received: from franka.aracnet.com ([216.99.193.44]:1197 "EHLO franka.aracnet.com") by vger.kernel.org with ESMTP id ; Fri, 21 Feb 2003 02:09:25 -0500 Date: Thu, 20 Feb 2003 23:19:27 -0800 From: "Martin J. Bligh" To: Andrew Morton cc: linux-kernel@vger.kernel.org Subject: Re: Strange performance change 59 -> 61/62 Message-ID: <17280000.1045811967@[10.10.2.4]> In-Reply-To: <20030219101957.05088aa1.akpm@digeo.com> References: <32720000.1045671824@[10.10.2.4]> <20030219101957.05088aa1.akpm@digeo.com> 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 >> I'm comparing 59-mjb6 to 61-mjb1 and notice some strange performance >> differences that I can't explain ... not a big drop, but odd. >> ... >> >> 1562 .text.lock.file_table >> 583 dentry_open >> 551 get_empty_filp > > The first one here is fget(). That's causing problems on ppc64 as well - the > machine is spending as long in fget as it is in copy_foo_user() in dbench > runs. > > One possibility is that we're calling fget() more often than previously, > although that would be rather odd. Can you add the below patch, and monitor > /proc/meminfo:nr_fgets? Thanks for the patch, sorry it took me so long to get the testing done. 59: 4742165 61: 4743166 Pretty damned close ;-) > If not that, then maybe some funny cacheline aliasing thing? Mmm... you mean like something sharing the cacheline with the file lock? M.