From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751569Ab2A2GJ3 (ORCPT ); Sun, 29 Jan 2012 01:09:29 -0500 Received: from mga14.intel.com ([143.182.124.37]:33073 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751114Ab2A2GJY (ORCPT ); Sun, 29 Jan 2012 01:09:24 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="100771464" Date: Sun, 29 Jan 2012 13:59:17 +0800 From: Wu Fengguang To: Eric Dumazet Cc: Herbert Poetzl , Andrew Morton , LKML , Jens Axboe , Tejun Heo Subject: Re: Bad SSD performance with recent kernels Message-ID: <20120129055917.GB8513@localhost> References: <20120127060034.GG29272@MAIL.13thfloor.at> <20120128125108.GA9661@localhost> <1327757611.7199.6.camel@edumazet-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1327757611.7199.6.camel@edumazet-laptop> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 28, 2012 at 02:33:31PM +0100, Eric Dumazet wrote: > Le samedi 28 janvier 2012 à 20:51 +0800, Wu Fengguang a écrit : > > > Would you please create a filesystem and large file on sda and run the > > tests on the file? There was some performance bug on reading the raw > > /dev/sda device file.. > > Hmm... latest kernel has the performance bug right now. > > Really if /dev/sda is slow, we are stuck. What's the block size? If it's < 4k, performance might be hurt. blockdev --getbsz /dev/sda > FYI, I started a bisection. Thank you! If the bisection would take much human time, it should be easier to collect some blktrace data on reading /dev/sda for analyzes. Thanks, Fengguang