Re: [Qemu-devel] Migration ToDo list (a.k.a. Rant)

[Eric Blake]

On 05/04/2016 05:20 AM, Juan Quintela wrote:
> - migration capabilities and parameters
>   this is a mess.  Not, is worse than that.  I don't know who is to
>   blame here, but something needs to be done:
> 
>      void qmp_migrate_set_parameters(bool has_compress_level,
>                                 int64_t compress_level,
>                                 bool has_compress_threads,
>                                 int64_t compress_threads,
>                                 bool has_decompress_threads,
>                                 int64_t decompress_threads,
>                                 bool has_x_cpu_throttle_initial,
>                                 int64_t x_cpu_throttle_initial,
>                                 bool has_x_cpu_throttle_increment,
>                                 int64_t x_cpu_throttle_increment,
>                                 bool has_multifd_threads,
>                                 int64_t multifd_threads,
>                                 Error **errp)

I've got a QAPI patch in the pipeline that makes this MUCH simpler, by
boxing everything through a single MigrationParameter* pointer rather
than an exploded list of parameters.


>    migrate_set_capability
>       Minor nickpit, if it only allow booleans, "migrate_set_capability 
> x-multifd",
>       should be an equivalent of "migrate_set_capability x-multifd on"

That's HMP - you can make HMP do whatever you want without breaking
back-compat.

> 
>    migrate_set_cache_size
>    migrate_set_downtime
>    migrate_set_speed
>       This three should be claimed obsolete, deprecated, whatever, and
>       make it on top of next one

Again, HMP can make this change easy, even if it has to call out to
different QMP under the hood.

> 
>    migrate_set_parameter
> 
>    Now to read the migration information:
> 
>      migrate_capabilities
>        good
>      migrate_parameters
>        good

Why we need two commands is beyond me - one command that lists
everything (capabilities AND parameters) should be sufficient.


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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