Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754141AbXEBC1S (ORCPT ); Tue, 1 May 2007 22:27:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754050AbXEBC1S (ORCPT ); Tue, 1 May 2007 22:27:18 -0400 Received: from nz-out-0506.google.com ([64.233.162.229]:37495 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754141AbXEBC1R (ORCPT ); Tue, 1 May 2007 22:27:17 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=KBXzTG6A2jY0kJREr7sNRWczzatJ1A+GA/vj0TQsmC+IQM31fLa4Ky0Yg81Xv3RyjAX8XlmxX11c9738iJFTAdl6pvkpMWIQPT+Vky5G1s8gca42zlQLt80FwFovUtSB8aSE2SoCcPNDo4SfJM/TTyij2do1fWB+nOdCoYOIky8= Message-ID: <5c49b0ed0705011927n66208c1egd7cfdb6985dc901b@mail.gmail.com> Date: Tue, 1 May 2007 19:27:16 -0700 From: "Nate Diller" To: "Christoph Lameter" Subject: Re: [PATCH] zero_user_page uses in fs/buffer.c and fs/libfs.c Cc: "Andrew Morton" , "Satyam Sharma" , linux-kernel@vger.kernel.org In-Reply-To: <5c49b0ed0705011916y89212c0v1cec1cb1edae052f@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20070501172643.270bb061.akpm@linux-foundation.org> <5c49b0ed0705011916y89212c0v1cec1cb1edae052f@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1694 Lines: 39 On 5/1/07, Nate Diller wrote: > On 5/1/07, Christoph Lameter wrote: > > On Tue, 1 May 2007, Andrew Morton wrote: > > > > > As Satyam said, this will sometimes cause us to map and unmap the page > > > twice, and to run flush_dcache_page() twice. In not-terribly-uncommon > > > circumstances in very frequently called functions. > > > > > > Doesn't seem worth it to me. > > > > Ok but we have that code three times. Should I add a variant of > > zero_user_page that zeroes everything but the section specified? > > > > zero_user_page_allbut() ? > > the function already exists, it's called simple_prepare_write(), and i > thought there were patches to convert those callsites in -mm ... > although it looks like i let a review comment on that slide by. I > need to redo a bunch of patches for re-submission anyway, so i guess > i'll deal with that tomorrow. > > NATE > well, leave it to me to reply too quickly, sorry. i think we should leave simple_prepare_write() the way it is, since it's a library function itself. the other two callsites in your patch are buffers, which may themselves be smaller than a page so you would need a special function for just those two uses, there's no other way to avoid making two calls to flush_dcache_page(). if it's tremendously important to you to eliminate open coding of these, maybe make a 'static int buffer_prepare_write()' or some such in fs/buffer.c NATE - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/