From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753120Ab1KOEyQ (ORCPT ); Mon, 14 Nov 2011 23:54:16 -0500 Received: from sous-sol.org ([216.99.217.87]:60917 "EHLO sequoia.sous-sol.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751087Ab1KOEyO (ORCPT ); Mon, 14 Nov 2011 23:54:14 -0500 Date: Mon, 14 Nov 2011 20:54:04 -0800 From: Chris Wright To: cody Cc: David Woodhouse , Roland Dreier , linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Chris Wright Subject: Re: [PATCH] intel-iommu: Default to non-coherent for domains unattached to iommus Message-ID: <20111115045404.GC30247@sequoia.sous-sol.org> References: <20111111224849.9756.13368.stgit@bling.home> <1321058267.2006.21.camel@shinybook.infradead.org> <20111112005100.GR14486@sequoia.sous-sol.org> <1321059340.2006.27.camel@shinybook.infradead.org> <20111112010850.GT14486@sequoia.sous-sol.org> <1321060841.2006.35.camel@shinybook.infradead.org> <4EC210CB.1010409@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4EC210CB.1010409@gmail.com> User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * cody (mail.kai.huang@gmail.com) wrote: > On 11/11/2011 05:20 PM, David Woodhouse wrote: > >On Fri, 2011-11-11 at 17:08 -0800, Chris Wright wrote: > >>On a slightly separate, but performance related note...have you ever > >>tried using the hw queue? Currently we only have a sw queue, but the > >>submission path for invalidations doesn't really queue (unless I missed > >>it). It seems to pull from the software queue and submit/wait, > >>submit/wait...Seems simple enough to submit the whole queue and then > >>issue the wait. > >I have a feeling we trigger errata if we do that — although if we're > >only doing it for an emulated IOMMU that shouldn't be an issue. > > > What does the emulated IOMMU here? Does it mean the emulated IOMMU > exposed to guest VM? Yes. So for KVM, the IOMMU emulation would be in QEMU. thanks, -chris