Re: [Qemu-devel] [RFC PATCH 0/5] asynchronous migration state change handlers

[Anthony Liguori <anthony@codemonkey.ws>]

On 06/05/2012 01:49 PM, Yonit Halperin wrote:
> Hi,
>
> I'm sending this patch series again. This time with an additional patch
> for setting a migrate_end notifier completion callback for spice migration
> interface. I've also added more detailed commit messages.
>
> This patch series introduces async handlers for notifiers, and integrates them
> with migration state change notifications.
>
> Asynchronous migration completion notifier is essential for allowing spice to cleanly
> complete the src server connection to the client, and transfer the connection to the target.
> Currently, as soon as the migration completes, the src qemu can be closed by the
> management, and spice cannot complete the spice-connection migration.
>
> In order to support spice seamless migration, next to these patches, I plan to add:
> (1) notifier for switching from the live phase of the migration to the non-live phase,
>      before completing savevm.
>      Spice will use this notification to "finalize" the connection to the client: send
>      and receive all in-flight data.

Absolutely not.  This is hideously ugly and affects a bunch of code.

Spice is *not* getting a hook in migration where it gets to add arbitrary 
amounts of downtime to the migration traffic.  That's a terrible idea.

I'd like to be more constructive in my response, but you aren't explaining the 
problem well enough for me to offer an alternative solution.  You need to find 
another way to solve this problem.

Regards,

Anthony Liguori