From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755686Ab0EEAPH (ORCPT ); Tue, 4 May 2010 20:15:07 -0400 Received: from bld-mail14.adl6.internode.on.net ([150.101.137.99]:49471 "EHLO mail.internode.on.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752151Ab0EEAPF (ORCPT ); Tue, 4 May 2010 20:15:05 -0400 Date: Wed, 5 May 2010 10:14:58 +1000 From: Dave Chinner To: "Trenton D. Adams" Cc: Linux Kernel Mailing List Subject: Re: Flash IO slow 1.5 MB/s Message-ID: <20100505001458.GE8120@dastard> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Mon, May 03, 2010 at 09:52:44PM -0600, Trenton D. Adams wrote: > If I mount my usb key with "sync" option, I get 500kb or less transfer > speeds. If I use the gnome defaults, I get 60M+ for awhile, and then > it continually drops over time, down to the 500kb/s again. Gnome > defaults are... > > /dev/sdc1 on /media/FLASH type vfat > (rw,nosuid,nodev,noatime,uhelper=hal,shortname=lower,flush,uid=500) > > I have done similar tests on both Rally2 64G usb stick and sandisk > ultra (15M/s) SDHC 8G cards. I get lousy performance on both, unless > I set dirty bytes. These are both FAT 32. But, as you can see below, > 14 minutes to transfer less than a couple gigs is a little nutty. The > 3 minutes is a lot nicer. I am using 2.6.33 with a patch from > https://bugzilla.kernel.org/show_bug.cgi?id=15374 Perhaps it might be worth taking the writeback tracing code from this patch series: http://marc.info/?l=linux-fsdevel&m=127173141007222&w=2 And seeing what that tells you about how writeback is acting differently.... Cheers, Dave. -- Dave Chinner david@fromorbit.com