Re: [Qemu-devel] [CFR 4/10] qmp: migrate_set_downtime command

[Stefan Hajnoczi <stefanha@gmail.com>]

On Wed, Jun 16, 2010 at 4:45 PM, Stefan Hajnoczi
<stefanha@linux.vnet.ibm.com> wrote:
> migrate_set_downtime
> --------------------
>
> Set maximum tolerated downtime (in seconds) for migrations.
>
> Arguments:
>
> - "value": maximum downtime (json-number)
>
> Example:
>
> -> { "execute": "migrate_set_downtime", "arguments": { "value": 0.1 } }
> <- { "return": {} }

What are the semantics of this value?  I imagine it has to do with the rate of
transferring dirty pages and deciding when to suspend the machine to perform
the final steps of migration.

Is there a need to query this value, too?  The ability to set the value is
probably enough, I can't think of a situation where you need to query it rather
than just setting a new value.

Can this value be changed once migration is in progress?

Stefan