From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754742Ab1LDQeE (ORCPT ); Sun, 4 Dec 2011 11:34:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:14186 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754592Ab1LDQeA (ORCPT ); Sun, 4 Dec 2011 11:34:00 -0500 Message-ID: <4EDBA0F0.4000907@redhat.com> Date: Sun, 04 Dec 2011 18:33:52 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111115 Thunderbird/8.0 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: Sasha Levin , Rusty Russell , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, markmc@redhat.com Subject: Re: [PATCH] virtio-ring: Use threshold for switching to indirect descriptors References: <20111201075847.GA5479@redhat.com> <1322726977.3259.3.camel@lappy> <20111201102640.GB8822@redhat.com> <87zkfbre9x.fsf@rustcorp.com.au> <1322913028.3782.4.camel@lappy> <4EDB5EF0.2010909@redhat.com> <20111204120132.GB18758@redhat.com> <4EDB624A.3030403@redhat.com> <20111204151148.GA21851@redhat.com> <4EDB8EEB.4070309@redhat.com> <20111204160053.GA22501@redhat.com> In-Reply-To: <20111204160053.GA22501@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/04/2011 06:00 PM, Michael S. Tsirkin wrote: > > If you > > copy descriptors, then it goes away. > > The avail ring could go away. used could if we make descriptors > writeable. IIUC it was made RO in the hope that will make it > easier for xen to adopt. Still relevant? You mean RO from the consumer side? Why can't Xen do that? > > That does suck. Are there issues in increasing the ring size? Or > > making it discontiguous? > > discontiguous ring is what indirect is, basically. No, discontiguous is more cache and prefetch friendly. With vmap(), the code doesn't even change. -- error compiling committee.c: too many arguments to function