From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932483AbVHNKpf (ORCPT ); Sun, 14 Aug 2005 06:45:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932484AbVHNKpf (ORCPT ); Sun, 14 Aug 2005 06:45:35 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:43215 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S932483AbVHNKpe (ORCPT ); Sun, 14 Aug 2005 06:45:34 -0400 Date: Sun, 14 Aug 2005 11:45:33 +0100 From: Christoph Hellwig To: Arjan van de Ven Cc: hyoshiok@miraclelinux.com, linux-kernel@vger.kernel.org Subject: Re: [RFC] [PATCH] cache pollution aware __copy_from_user_ll() Message-ID: <20050814104533.GA16936@infradead.org> Mail-Followup-To: Christoph Hellwig , Arjan van de Ven , hyoshiok@miraclelinux.com, linux-kernel@vger.kernel.org References: <98df96d305081402164ce52f8@mail.gmail.com> <1124012489.3222.13.camel@laptopd505.fenrus.org> <98df96d305081403222e75b232@mail.gmail.com> <1124015743.3222.17.camel@laptopd505.fenrus.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1124015743.3222.17.camel@laptopd505.fenrus.org> User-Agent: Mutt/1.4.2.1i X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > the problem is that the pay elsewhere is far more spread out, but not > less. At least generally.... > > I can see the point of a copy_from_user_nocache() or something, for > those cases where we *know* we are not going to use the copied data in > the cpu (but say, only do DMA). > But that should be explicit, not implicit, since the general case will > be that the kernel WILL use the data. Most of the callers probably want the normal one, but most of the copied data (buffered filesystem I/O) will want the non cache poluting one. So yes, doing this explicit makes a lot of sense.