Re: [Qemu-devel] [RFC 0/3] qmp: Return extra information on qom-list-types

[Eric Blake]

On 05/24/2017 07:13 AM, Markus Armbruster wrote:

>>> Might lead to more traffic rather than less.  Depends on what
>>> information the client needs to query.
>>
>> I think queries that return all available QOM types are likely to
>> (should?) be cached by clients.
> 
> Perhaps libvirt developers can help us here.

Libvirt is very likely going to cache things (libvirt already tries to
cache as much information as it needs from a single run of a qemu
binary, and only recomputes the cache when either libvirt or qemu
binaries are detected to have changed to a newer timestamp).  Reading
the entire list, and then libvirt computing transitive closure on that
list if needed, is probably acceptable, compared to qemu having to
compute transitive closure up front for a larger QMP message.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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