From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751059AbWFXTdB (ORCPT ); Sat, 24 Jun 2006 15:33:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751060AbWFXTdB (ORCPT ); Sat, 24 Jun 2006 15:33:01 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:15514 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1751058AbWFXTdA (ORCPT ); Sat, 24 Jun 2006 15:33:00 -0400 Subject: Re: [PATCH] x86: cache pollution aware __copy_from_user_ll() From: Arjan van de Ven To: Linus Torvalds Cc: Linux Kernel Mailing List , akpm@osdl.org In-Reply-To: References: <200606231501.k5NF1B79002899@hera.kernel.org> <1151160152.3181.59.camel@laptopd505.fenrus.org> Content-Type: text/plain Date: Sat, 24 Jun 2006 21:32:56 +0200 Message-Id: <1151177576.3181.79.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit 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 On Sat, 2006-06-24 at 12:21 -0700, Linus Torvalds wrote: > > On Sat, 24 Jun 2006, Arjan van de Ven wrote: > > > > while this patch will reduce the number of cycles spent in the kernel, > > it's just pushing the cache miss to userspace (by virtue of doing a > > cache flush effectively)... is this really the right thing? The total > > memory bandwidth will actually increase with this patch if you're > > unlucky (eg if userspace decides to write to this memory eventually).... > > No. It's for copying _from_ user space, ie a "write()" system call. eh DOH never mind