Re: [Qemu-devel] [PATCH v4] XBZRLE delta for live migration of large memory apps

[Avi Kivity]

On 08/10/2011 07:23 PM, Anthony Liguori wrote:
> > Right now we have capabilties in the form of -help output.
> >
> > If -help says
> >
> > -no-xzbrle disable xzbrle support
> >
> > (or -migration-compression xzbrle=off, or something) that's sufficient
> > for management tools.
>
>
> This is static, not dynamic.  You may attempt to migrate to another 
> host that supports it and then migrate to a second host that doesn't 
> support it after the first migration fails.

This may be acceptable, wait until the entire migration cluster is 
xzbrle capable before enabling it.  If not, add a monitor command.

> > We shouldn't block this feature just because some monitor facility is
> > not yet implemented.
>
> We shouldn't make *any* changes to the migration protocol before we 
> have a feature negotiation capability.  I only want to do a hard break 
> of the protocol once.

Didn't we agree that management tool mediated feature negotiation (that 
is, outside the migration protocol itself) is acceptable?

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