From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992651AbXCXBB5 (ORCPT ); Fri, 23 Mar 2007 21:01:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2992652AbXCXBB5 (ORCPT ); Fri, 23 Mar 2007 21:01:57 -0400 Received: from smtp-out.google.com ([216.239.45.13]:15854 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2992651AbXCXBB4 (ORCPT ); Fri, 23 Mar 2007 21:01:56 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:message-id:date:from:to:subject:in-reply-to: mime-version:content-type:content-transfer-encoding: content-disposition:references; b=CR4btezyS9TjcYaoZ0V4NFjWnFjfIQraXrwqPk+c3azlVr98hpBZwSPqHn2yJC+Cl wo75sV9q//Nq3rfrG7krQ== Message-ID: Date: Fri, 23 Mar 2007 18:01:49 -0700 From: "Ken Chen" To: "Christoph Hellwig" , "Ken Chen" , "Andrew Morton" , linux-kernel@vger.kernel.org Subject: Re: [patch] cache pipe buf page address for non-highmem arch In-Reply-To: <20070323101452.GA15144@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20070323101452.GA15144@infradead.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 3/23/07, Christoph Hellwig wrote: > I think you're fixing the symptom here and not the cause. If calculating > the virtual address of a page is so expensive on your setup it should > define WANT_PAGE_VIRTUAL and we should always cache the virtual address > in struct page. There's a lot more code, epecially in filesystems that's > rather upset about a slow page_address. Adding WANT_PAGE_VIRTUAL would be too costly I think as it will expand the sizeof struct page. I would rather go incremental fix on these issues and not blindly increase page struct size.