From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964827Ab2CSIol (ORCPT ); Mon, 19 Mar 2012 04:44:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60242 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757027Ab2CSIok (ORCPT ); Mon, 19 Mar 2012 04:44:40 -0400 Date: Mon, 19 Mar 2012 10:44:51 +0200 From: "Michael S. Tsirkin" To: Rusty Russell Cc: Jason Wang , netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [V4 PATCH] virtio-net: send gratuitous packet when needed Message-ID: <20120319084449.GF17673@redhat.com> References: <20120313090841.11110.82654.stgit@amd-6168-8-1.englab.nay.redhat.com> <20120313143331.GE14931@redhat.com> <877gyhxrlu.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <877gyhxrlu.fsf@rustcorp.com.au> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 19, 2012 at 12:46:29PM +1030, Rusty Russell wrote: > On Tue, 13 Mar 2012 16:33:31 +0200, "Michael S. Tsirkin" wrote: > > > diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h > > > index 970d5a2..44a38d6 100644 > > > --- a/include/linux/virtio_net.h > > > +++ b/include/linux/virtio_net.h > > > @@ -49,8 +49,10 @@ > > > #define VIRTIO_NET_F_CTRL_RX 18 /* Control channel RX mode support */ > > > #define VIRTIO_NET_F_CTRL_VLAN 19 /* Control channel VLAN filtering */ > > > #define VIRTIO_NET_F_CTRL_RX_EXTRA 20 /* Extra RX mode control support */ > > > +#define VIRTIO_NET_F_GUEST_ANNOUNCE 21 /* Guest can send gratituous packet */ > > > > > > #define VIRTIO_NET_S_LINK_UP 1 /* Link is up */ > > > +#define VIRTIO_NET_S_ANNOUNCE 2 /* Announcement is needed */ > > > > I would put this in bit 8 (0x100), this way low status byte > > is RO, high byte is RW. > > The whole idea of acking by clearing the bit is unreliable, moving to a > separate byte just controls the damage. > > How about you use bits 8-15 as a counter? It's still theoretically > unreliable if 256 notifications pass before the guest notices, but it's > probably better and clearer than this. > > I leave the final call to MST though. > > Thanks, > Rusty. I guess the point was that we want a single packet so we don't care if multiple notifications are coalesced into a single one. > -- > How could I marry someone with more hair than me? http://baldalex.org