From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752674Ab2A0Sww (ORCPT ); Fri, 27 Jan 2012 13:52:52 -0500 Received: from mail-wi0-f174.google.com ([209.85.212.174]:63702 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751453Ab2A0Swu convert rfc822-to-8bit (ORCPT ); Fri, 27 Jan 2012 13:52:50 -0500 MIME-Version: 1.0 In-Reply-To: <1327684589.12089.22.camel@joe2Laptop> References: <1327674295-3700-1-git-send-email-akinobu.mita@gmail.com> <1327674295-3700-2-git-send-email-akinobu.mita@gmail.com> <1327684589.12089.22.camel@joe2Laptop> Date: Fri, 27 Jan 2012 10:52:49 -0800 Message-ID: Subject: Re: [PATCH] mtd/nand: use string library From: Brian Norris To: Joe Perches Cc: Akinobu Mita , Scott Branden , linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, Jiandong Zheng , akpm@linux-foundation.org, David Woodhouse Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 27, 2012 at 9:16 AM, Joe Perches wrote: > On Fri, 2012-01-27 at 23:24 +0900, Akinobu Mita wrote: >> - Use memchr_inv to check if the data contains all 0xFF bytes. >>   It is faster than looping for each byte. > > Stupid question: > > Are there any mtd devices modified that are slower > at 64 bit accesses than repeated 8 bit accesses? I believe this patch deals with kernel buffers, not any kind of direct access to the MTD, so the question (which is not stupid IMO) should be regarding CPU architectures. And my educated guess is that 64-bit access should not be any slower. I do know that 8-bit access *is* slower for some relevant architectures. Brian