From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262195AbTJAPSM (ORCPT ); Wed, 1 Oct 2003 11:18:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262241AbTJAPSL (ORCPT ); Wed, 1 Oct 2003 11:18:11 -0400 Received: from fw.osdl.org ([65.172.181.6]:42460 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S262195AbTJAPSH (ORCPT ); Wed, 1 Oct 2003 11:18:07 -0400 Date: Wed, 1 Oct 2003 08:19:10 -0700 From: Andrew Morton To: Andi Kleen Cc: jamie@shareable.org, hugh@veritas.com, ak@suse.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Mutilated form of Andi Kleen's AMD prefetch errata patch Message-Id: <20031001081910.70d4751b.akpm@osdl.org> In-Reply-To: <20031001145631.GK22333@wotan.suse.de> References: <20031001073132.GK1131@mail.shareable.org> <20031001093329.GA2649@mail.shareable.org> <20031001075151.4e595f99.akpm@osdl.org> <20031001145631.GK22333@wotan.suse.de> X-Mailer: Sylpheed version 0.9.4 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote: > > > I'm a bit confused as to what significance the faulting address has btw: > > kernel code can raise prefetch faults against addresses which are less > > than, and presumably greater than TASK_SIZE. > > Currently it can't - hlist either prefetches to zero or to a valid > address and everybody else using prefetch should also use valid addresses. mumble, mutter. > But it's conceivable that future kernels make more extensive use of > prefetch. yup. Why is it not sufficient to do something like: if (!(error_code & 4) && is_prefetch(...)) return; near the start of do_page_fault()? kernel-mode faults aren't very common. Most of them occur in generic_file_read(), for reads into freshly-allocated memory (I think). And the frequency of these is limited by disk bandwidth...