From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268856AbUJKMTb (ORCPT ); Mon, 11 Oct 2004 08:19:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268861AbUJKMTa (ORCPT ); Mon, 11 Oct 2004 08:19:30 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:63239 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S268856AbUJKMTX (ORCPT ); Mon, 11 Oct 2004 08:19:23 -0400 Date: Mon, 11 Oct 2004 13:19:19 +0100 From: Russell King To: Pierre Ossman Cc: LKML Subject: Re: MMC performance Message-ID: <20041011131919.B19175@flint.arm.linux.org.uk> Mail-Followup-To: Pierre Ossman , LKML References: <416A68E5.6080608@drzeus.cx> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <416A68E5.6080608@drzeus.cx>; from drzeus-list@drzeus.cx on Mon, Oct 11, 2004 at 01:05:09PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 11, 2004 at 01:05:09PM +0200, Pierre Ossman wrote: > Writing, however, only sends a single sector at a time. The queue > process eats up half of the CPU time on my machine during a write. And > since MMC cards have to clear a whole bunch of sectors before a write > shouldn't you send as many sectors as possible to them? Only if you can reliably know how many bytes you've tranferred when an error occurs. Without that, the only safe way to do a write is sector by sector. And there are MMC controllers which just don't give you that information, namely those found in Intel chips... Since I'm having to be compatible with existing drivers, we need to do this for the time being. It's a shame we can't tell the BIO layer about this type of quirk though. Not that BIO itself understands "sector by sector" IO at the moment. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ 2.6 Serial core