From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756705Ab1GMQqh (ORCPT ); Wed, 13 Jul 2011 12:46:37 -0400 Received: from adelie.canonical.com ([91.189.90.139]:59977 "EHLO adelie.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756255Ab1GMQqf (ORCPT ); Wed, 13 Jul 2011 12:46:35 -0400 Date: Wed, 13 Jul 2011 11:46:27 -0500 (CDT) From: Manoj Iyer X-X-Sender: manjo@lazy To: Arnd Bergmann cc: Manoj Iyer , Chris Ball , linux-kernel@vger.kernel.org, jbarnes@virtuousgeek.org, matsumur@nts.ricoh.co.jp, linux-pci@vger.kernel.org, linux-mmc@vger.kernel.org Subject: Re: [PATCH] mmc: Added quirks for Ricoh 1180:e823 lower base clock frequency In-Reply-To: <201107131835.25217.arnd@arndb.de> Message-ID: References: <1310419715-13254-1-git-send-email-manoj.iyer@canonical.com> <201107131835.25217.arnd@arndb.de> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Chris, Do you think that lowering the controller speed to 50Mhz in case we have a failure is a better idea than reducing the speed for all e823 ricoh controllers? I can send a V2 of the patch. What do you think ? On Wed, 13 Jul 2011, Arnd Bergmann wrote: > On Wednesday 13 July 2011, Manoj Iyer wrote: >> >> Chris/Arnd, >> >> Here is a series of test I did with the patched kernel. > >> == cold boot insert SD card == >> u@u:~/flash/flashbench$ sudo ./flashbench -O --erasesize=$[4 * 1024 * >> 1024] --blocksize=$[256 * 1024] /dev/mmcblk0 --open-au-nr=2 >> 4MiB 4.96M/s >> 2MiB 6.3M/s >> 1MiB 6.23M/s >> 512KiB 6.23M/s >> 256KiB 6.26M/s > > The very first one obviously triggers a garbage collection. > Everything after that is well within measuring accuracy around 6.25MB/s > >> On Wed, 13 Jul 2011, Chris Ball wrote: > >>> >>> That makes sense. Do you think this explains Manoj getting a slower >>> first file copy speed (757ms vs. 480ms) after applying his patch? >>> (Manoj, perhaps you could retry your test without GC being needed?) > > Yes. For a single sample, it can easily explain differences up to 500ms. > You have to average out file system benchmarks across a lot of files > to be sure. > >>> What would we expect lowering the SD base clock frequency from 200MHz >>> to 50MHz to do to performance theoretically? > > Not much. This card only has a 6MB/s write speed, which is well below > what a 50 MHz bus can do. It mgiht be different on a fast eMMC device > or a Sandisk Extreme Pro UHS-1 card. > > Arnd > > -- ==================== Manoj Iyer Ubuntu/Canonical Hardware Enablement ====================