From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754682AbZHMO6R (ORCPT ); Thu, 13 Aug 2009 10:58:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754644AbZHMO6Q (ORCPT ); Thu, 13 Aug 2009 10:58:16 -0400 Received: from moutng.kundenserver.de ([212.227.126.177]:64497 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754639AbZHMO6P (ORCPT ); Thu, 13 Aug 2009 10:58:15 -0400 From: Arnd Bergmann To: "Michael S. Tsirkin" Subject: Re: [PATCH 2/2] vhost_net: a kernel-level virtio server Date: Thu, 13 Aug 2009 16:58:06 +0200 User-Agent: KMail/1.12.0 (Linux/2.6.31-5-generic; KDE/4.3.0; x86_64; ; ) Cc: virtualization@lists.linux-foundation.org, "Ira W. Snyder" , netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <200908131538.44465.arnd@arndb.de> <20090813143922.GA5080@redhat.com> In-Reply-To: <20090813143922.GA5080@redhat.com> X-Face: I@=L^?./?$U,EK.)V[4*>`zSqm0>65YtkOe>TFD'!aw?7OVv#~5xd\s,[~w]-J!)|%=]> =?utf-8?q?+=0A=09=7EohchhkRGW=3F=7C6=5FqTmkd=5Ft=3FLZC=23Q-=60=2E=60Y=2Ea=5E?= =?utf-8?q?3zb?=) =?utf-8?q?+U-JVN=5DWT=25cw=23=5BYo0=267C=26bL12wWGlZi=0A=09=7EJ=3B=5Cwg?= =?utf-8?q?=3B3zRnz?=,J"CT_)=\H'1/{?SR7GDu?WIopm.HaBG=QYj"NZD_[zrM\Gip^U MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200908131658.06522.arnd@arndb.de> X-Provags-ID: V01U2FsdGVkX19CXqlnNEqaeNjxjQVdEVR+6uxE9gUtOkx+MKQ Gv3bpmYvHPLh2Yifa76twPrdeNZrJOjKOHZ+NKMiDMQzr07PjV MRRKTp0RKJ605RIK/qFyg== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 13 August 2009, Michael S. Tsirkin wrote: > > Right now, the number of copy operations in your code is the same. > > You are doing the copy a little bit later in skb_copy_datagram_iovec(), > > which is indeed a very nice hack. Changing to a virtqueue based method > > would imply that the host needs to add each skb_frag_t to its outbound > > virtqueue, which then gets copied into the guests inbound virtqueue. > > Which is a lot more code than just calling skb_copy_datagram_iovec. Well, I don't see this part as much of a problem, because the code already exists in virtio_net. If we really wanted to go down that road, just using virtio_net would solve the problem of frame handling entirely, but create new problems elsewhere, as we have mentioned. Arnd <><