Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754419AbXJVDfJ (ORCPT ); Sun, 21 Oct 2007 23:35:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751646AbXJVDe5 (ORCPT ); Sun, 21 Oct 2007 23:34:57 -0400 Received: from gw.goop.org ([64.81.55.164]:35313 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751543AbXJVDe4 (ORCPT ); Sun, 21 Oct 2007 23:34:56 -0400 Message-ID: <471C1A61.1010001@goop.org> Date: Sun, 21 Oct 2007 20:34:57 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.5 (X11/20070727) MIME-Version: 1.0 To: dean gaudet CC: Nick Piggin , David Chinner , xfs@oss.sgi.com, Xen-devel , Linux Kernel Mailing List , Mark Williamson , =?ISO-8859-1?Q?Morten_?= =?ISO-8859-1?Q?B=F8geskov?= , xfs-masters@oss.sgi.com Subject: Re: Interaction between Xen and XFS: stray RW mappings References: <470FA7C3.90404@goop.org> <20071014225618.GN23367404@sgi.com> <4712A254.4090604@goop.org> <200710151415.07248.nickpiggin@yahoo.com.au> In-Reply-To: X-Enigmail-Version: 0.95.3 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 781 Lines: 22 dean gaudet wrote: > On Mon, 15 Oct 2007, Nick Piggin wrote: > > >> Yes, as Dave said, vmap (more specifically: vunmap) is very expensive >> because it generally has to invalidate TLBs on all CPUs. >> > > why is that? ignoring 32-bit archs we have heaps of address space > available... couldn't the kernel just burn address space and delay global > TLB invalidate by some relatively long time (say 1 second)? > Yes, that's precisely the problem. xfs does delay the unmap, leaving stray mappings, which upsets Xen. J - 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/