From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758509AbZDWODT (ORCPT ); Thu, 23 Apr 2009 10:03:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754886AbZDWODJ (ORCPT ); Thu, 23 Apr 2009 10:03:09 -0400 Received: from mx2.redhat.com ([66.187.237.31]:59868 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752914AbZDWODJ (ORCPT ); Thu, 23 Apr 2009 10:03:09 -0400 From: Jeff Moyer To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Jens Axboe Subject: 2.6.30-rc deadline scheduler performance regression for iozone over NFS X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Thu, 23 Apr 2009 10:01:58 -0400 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I've been working on CFQ improvements for interleaved I/Os between processes, and noticed a regression in performance when using the deadline I/O scheduler. The test uses a server configured with a cciss array and 1Gb/s ethernet. The iozone command line was: iozone -s 2000000 -r 64 -f /mnt/test/testfile -i 1 -w The numbers in the nfsd's row represent the number of nfsd "threads". These numbers (in MB/s) represent the average of 5 runs. v2.6.29 nfsd's | 1 | 2 | 4 | 8 --------+---------------+-------+------ deadline| 43207 | 67436 | 96289 | 107590 2.6.30-rc1 nfsd's | 1 | 2 | 4 | 8 --------+---------------+-------+------ deadline| 43732 | 68059 | 76659 | 83231 2.6.30-rc3.block-for-linus nfsd's | 1 | 2 | 4 | 8 --------+---------------+-------+------ deadline| 46102 | 71151 | 83120 | 82330 Notice the drop for 4 and 8 threads. It may be worth noting that the default number of NFSD threads is 8. Cheers, Jeff