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

[Avi Kivity]

On 08/08/2011 05:56 PM, Stefan Hajnoczi wrote:
> >  IOW, this should be part of the standard migration protocol, not some side
> >  option that is enabled if the user remembers.  It should not be mutually
> >  exclusive with future migration extensions, including compression.
>
> This is an attractive option.  With some polish maybe XBZRLE could be
> integrated as a default option that does not degrade performance.
> Adding features that require user configuration isn't worthwhile
> because they won't be used or they'll be misused - let's not make QEMU
> more complicated if it can be avoided.
>
> If there is no way to make XBZRLE automatic then I think it should
> live outside QEMU because it will be a niche feature that relatively
> few will use but adds complexity to migration.

Agree.  Aidan, can you provide impact numbers on non-XBZRLE favourable 
workloads (both throughput and cpu usage)?  What about turning itself 
off automatically if the hit rate is too low?

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