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From: Paolo Bonzini <pbonzini@redhat.com>
To: "Marc-André Lureau" <marcandre.lureau@gmail.com>
Cc: Linhaifeng <haifeng.lin@huawei.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Thibaut Collet <thibaut.collet@6wind.com>,
	jasowang@redhat.com, QEMU <qemu-devel@nongnu.org>,
	stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH v4 1/1] vhost user: add support of live migration
Date: Fri, 17 Jul 2015 14:57:26 +0200	[thread overview]
Message-ID: <55A8FBB6.5040607@redhat.com> (raw)
In-Reply-To: <CAJ+F1CK3vCdqyGcLy1wMJ_txTVzZTd6vHKr6=sc7uZmuUfKMHQ@mail.gmail.com>



On 17/07/2015 12:34, Marc-André Lureau wrote:
> On Fri, Jul 17, 2015 at 4:25 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> > But LOG_BASE makes little sense across processes, and LOG_FD is unused
> > in QEMU, isn't it?  So this patch is not enough to add support of live
> > migration.
>
> You are right, LOG_BASE doesn't make much sense, and LOG_FD isn't
> used, despite some code already there. Furthermore, the log is
> allocated with regular malloc, hardly shareable.

LOG_FD is implemented in the kernel drivers/vhost/vhost.c.  It seems to
be an eventfd-like mechanism to save on dirty bitmap scans.  However,
it's not well documented how to implement it in a correct way.

In any case, live migration needs a new message type (like LOG_MMAP_FD)
in the vhost-user protocol.

Paolo

  reply	other threads:[~2015-07-17 12:57 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-26  9:22 [Qemu-devel] [PATCH v4 0/1] Add live migration for vhost user Thibaut Collet
2015-06-26  9:22 ` [Qemu-devel] [PATCH v4 1/1] vhost user: add support of live migration Thibaut Collet
2015-07-10 13:05   ` Paolo Bonzini
2015-07-13  2:27     ` Linhaifeng
2015-07-17  0:19       ` Marc-André Lureau
2015-07-17  2:25         ` Paolo Bonzini
2015-07-17 10:34           ` Marc-André Lureau
2015-07-17 12:57             ` Paolo Bonzini [this message]
2015-07-17 13:35               ` Marc-André Lureau
2015-07-17 13:50                 ` Paolo Bonzini
2015-07-18  0:07                   ` Marc-André Lureau
2015-07-18 13:18                     ` Paolo Bonzini
2015-07-17  0:20 ` [Qemu-devel] [PATCH v4 0/1] Add live migration for vhost user Marc-André Lureau

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