Re: [Qemu-devel] [RFC PATCH v2] Throttle-down guest when live migration does not converge.

[Chegu Vinod <chegu_vinod@hp.com>]

On 4/29/2013 7:53 AM, Eric Blake wrote:
> On 04/27/2013 02:50 PM, Chegu Vinod wrote:
>> Busy enterprise workloads hosted on large sized VM's tend to dirty
>> memory faster than the transfer rate achieved via live guest migration.
>> Despite some good recent improvements (& using dedicated 10Gig NICs
>> between hosts) the live migration does NOT converge.
>>
>> No exernal trigger is required (unlike option 1) and it can co-exist
> s/exernal/external/
>
>> with enhancements being pursued as part of Option 2 (e.g. RDMA).
>>
>> Thanks to Juan and Paolo for their useful suggestions.
>>
>> ---
>>
>> (qemu) info migrate
>> capabilities: xbzrle: off auto-converge: on   <----
> This part looks nice.
>
> I'm not reviewing the entire patch (I'm not an expert on the internals
> of migration), but just the interface:

Thanks for taking a look at this. I shall incorporate your suggested 
changes in the
next version.

Hoping to hear from Juan/Orit and others on the live migration part.

Thanks,
Vinod

>> +++ b/qapi-schema.json
>> @@ -599,10 +599,14 @@
>>   #          This feature allows us to minimize migration traffic for certain work
>>   #          loads, by sending compressed difference of the pages
>>   #
>> +# @auto-converge: Controls whether or not the we want the migration to
>> +#          automaticially detect and force convergence by slowing
> s/automaticially/automatically/
>
>> +#          down the guest. Disabled by default.
> Missing a (since 1.6) designation.
>
> Also, use of first-person (us, we) in docs seems a bit unprofessional,
> although you were copying pre-existing usage.  How about:
>
> @xbzrle: Migration supports xbzrle (Xor Based Zero Run Length Encoding),
>           which minimizes migration traffic for certain workloads by
>           sending compressed differences of active pages
>
> @auto-converge: Migration supports automatic throttling of guest
>                  activity to force convergence (since 1.6)
>