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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <4EC17610.3000401@codemonkey.ws> (Anthony Liguori's message of
	"Mon, 14 Nov 2011 14:12:00 -0600")
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Date: Mon, 14 Nov 2011 21:28:55 +0100
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Subject: Re: [Qemu-devel] [PATCH 5/7] block: allow migration to work with
	image files (v2)
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Kevin Wolf <kwolf@redhat.com>, Lucas Meneghel Rodrigues <lmr@redhat.com>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, "Michael S. Tsirkin" <mst@redhat.com>, qemu-devel@nongnu.org, Avi Kivity <avi@redhat.com>

Anthony Liguori <anthony@codemonkey.ws> wrote:

>
> Michael basically was trying to avoid having a VM's state change after
> you stopped the guest.
>
> With something like cache=unsafe that periodically flushes based on a
> timer (I think), you want to make sure that that doesn't happen after
> stop occurs.

Even then, we want to have "qcow2_flush_dirty_buffer_to_disk()" or
whatever is going to be called the method.  Doing a full "drop all
cache" and "reread" it is using a cannon to fight flies IMHO.
Especially because there are "lots" of uses of stop, and only a minority
of them want this flushed to disk (if ever).

My recount of mst problems were with networking (vhost) than something
touch the guest image while VM is stopped.  This is not the case here,
as we are not doing anything with the guest memory, no?

Later, Juan.