[libvirt] question: about iothreads count restrict in virDomainDefCheckABIStabilityFlags

[Daniel P. Berrangé]

On Tue, Jan 29, 2019 at 05:33:30PM +0800, WangJie (Pluto) wrote:
> Hi,
> 
> Migrate feature have a restrict: target domain iothreads count
> must match source
> 
> The relevant code as follows:
> 
> ------------------------------------
> 
> if (src->niothreadids != dst->niothreadids) { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, _("Target domain iothreads count %zu does not " "match source %zu"), dst->niothreadids, src->niothreadids); goto error; }
> 
> 
> ------------------------------------
> 
> I tried to remove the restrict, and perform migrate in that case:
> "target domain iothreads count does not match source" , Anything
> is normal!
> 
> So, can we remove the restrict to support this case?

The number of i/o threads is not part of the vm state sent during
migration, nor exposed to the guest ABI, so this restriction is a
mistaken in libvirt. We should remove that bit of code.

Regards,
Daniel
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