From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750905AbWFCXxB (ORCPT ); Sat, 3 Jun 2006 19:53:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750911AbWFCXxB (ORCPT ); Sat, 3 Jun 2006 19:53:01 -0400 Received: from shawidc-mo1.cg.shawcable.net ([24.71.223.10]:13651 "EHLO pd2mo1so.prod.shaw.ca") by vger.kernel.org with ESMTP id S1750899AbWFCXxA (ORCPT ); Sat, 3 Jun 2006 19:53:00 -0400 Date: Sat, 03 Jun 2006 17:52:46 -0600 From: Robert Hancock Subject: Re: memcpy_toio on i386 using byte writes even when n%2==0 In-reply-to: <6inxv-4U2-17@gated-at.bofh.it> To: "H. Peter Anvin" , linux-kernel Message-id: <448220CE.4030709@shaw.ca> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: <6ined-4gY-17@gated-at.bofh.it> <6ined-4gY-21@gated-at.bofh.it> <6inee-4gY-23@gated-at.bofh.it> <6ined-4gY-15@gated-at.bofh.it> <6inxv-4U2-17@gated-at.bofh.it> User-Agent: Thunderbird 1.5.0.4 (Windows/20060516) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org H. Peter Anvin wrote: > For something that generates I/O transactions, it's imperative to > generate the smallest possible number of transactions. Furthermore, > smaller than dword transactions aren't burstable, except at the > beginning and end of a burst. Well, theoretically for writes they could be, if the memory region was prefetchable and the PCI chipset supported byte merge. It certainly isn't optimal however. -- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/