From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Peter Xu <peterx@redhat.com>
Cc: dev@dpdk.org, Victor Kaplansky <victork@redhat.com>
Subject: Re: [dpdk-dev] [PATCH 0/4 for 2.3] vhost-user live migration support
Date: Wed, 16 Dec 2015 10:50:19 +0800 [thread overview]
Message-ID: <20151216025019.GN29571@yliu-dev.sh.intel.com> (raw)
In-Reply-To: <20151216023803.GB20951@pxdev.xzpeter.org>
On Wed, Dec 16, 2015 at 10:38:03AM +0800, Peter Xu wrote:
> On Tue, Dec 15, 2015 at 04:07:57PM +0100, Thibaut Collet wrote:
> > After a migration, to avoid netwotk outage, all interfaces of the guest
> > must send a packet to update switches mapping (ideally a GARP).
> > As some interfaces do not do it QEMU does it in behalf of the guest by
> > sending a RARP (his RARP is not forged by the guest but by QEMU). This is
> > the qemu_self_announce purpose that "spoofs" a RARP to all backend of guest
> > ethernet interfaces. For vhost-user backend, QEMU can not do it directly
> > and asks to the vhost-user backend to do it with the VHOST_USER_SEND_RARP
> > request that contains the MAC address of the guest interface.
> >
> > Thibaut.
>
> Hi, Thibaut,
>
> Thanks for the explaination.
>
> Two more questions:
>
> 1. if vhost-user backend (or say, DPDK) supports GUEST_ANNOUNCE, and
> send another RARP (or say, GARP, I will use RARP as example),
> then there will be two RARP later on the line, right? (since the
> QEMU one is sent unconditionally from qemu_announce_self).
The one send by qemu_announce_self() will be caught by
vhost_user_receive(), which ends up invoking vhost_user_migration_done().
And it will be dropped when VIRTIO_NET_F_GUEST_ANNOUNCE is negotiated
there.
> 2. if the only thing vhost-user backend is to send another same RARP
> when got SEND_RARP request, why would it bother if QEMU will
> unconditionally send one? (or say, I still do not know why we
> need this SEND_RARP request, if the vhost-user backend is going
> to do the same thing again as QEMU already does)
Because that one is caught by vhost-user, and vhost-user just relays
it to the backend when necessary (say when GUEST_ANNOUNCE is not
supported)?
--yliu
next prev parent reply other threads:[~2015-12-16 2:50 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-11 8:26 Pavel Fedin
2015-12-11 9:49 ` Yuanhan Liu
2015-12-11 10:22 ` Pavel Fedin
2015-12-14 3:58 ` Peter Xu
2015-12-14 7:30 ` Pavel Fedin
2015-12-14 9:04 ` Peter Xu
2015-12-14 9:46 ` Pavel Fedin
2015-12-14 10:09 ` Peter Xu
2015-12-14 12:09 ` Yuanhan Liu
2015-12-14 13:00 ` Peter Xu
2015-12-14 13:21 ` Yuanhan Liu
2015-12-14 13:28 ` Peter Xu
2015-12-14 13:51 ` Yuanhan Liu
2015-12-14 14:54 ` Pavel Fedin
2015-12-15 8:23 ` Yuanhan Liu
2015-12-15 8:45 ` Pavel Fedin
2015-12-15 8:56 ` Yuanhan Liu
2015-12-15 9:04 ` Pavel Fedin
2015-12-15 10:05 ` Peter Xu
2015-12-15 11:43 ` Thibaut Collet
2015-12-15 11:47 ` Thibaut Collet
2015-12-15 12:24 ` Pavel Fedin
2015-12-15 13:36 ` Yuanhan Liu
2015-12-15 13:48 ` Pavel Fedin
2015-12-15 13:59 ` Yuanhan Liu
2015-12-15 14:58 ` Pavel Fedin
2015-12-16 7:28 ` Yuanhan Liu
2015-12-16 11:57 ` Pavel Fedin
2015-12-16 12:08 ` Yuanhan Liu
2015-12-16 12:43 ` Pavel Fedin
2015-12-16 13:00 ` Yuanhan Liu
2015-12-15 13:18 ` Yuanhan Liu
2015-12-15 15:07 ` Thibaut Collet
2015-12-15 15:36 ` Pavel Fedin
2015-12-16 2:38 ` Peter Xu
2015-12-16 2:50 ` Yuanhan Liu [this message]
2015-12-16 7:05 ` Pavel Fedin
2015-12-15 9:42 ` Peter Xu
-- strict thread matches above, loose matches on Subject: below --
2015-12-02 3:43 Yuanhan Liu
2015-12-02 14:10 ` Victor Kaplansky
2015-12-02 14:33 ` Yuanhan Liu
2015-12-09 3:41 ` Xie, Huawei
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