[libvirt] [PATCH 8/8] latency: Update cmdBlkStats to use new API

[Eric Blake]

On 09/02/2011 05:34 AM, Daniel Veillard wrote:
> On Fri, Sep 02, 2011 at 07:23:38PM +0800, Osier Yang wrote:
>> 于 2011年09月02日 18:21, Daniel Veillard 写道:
>>> On Wed, Aug 31, 2011 at 04:26:13PM +0800, Osier Yang wrote:
>>>> The modified function fallbacks to use virDomainBlockStats if
>>>> virDomainBlockStatsFlags is not supported by the hypervisor driver.
>>>> If the new API is supported, it will be invoked instead of the
>>>> old API.
>>>    Again I would use a new command and keep the existing code
>>> as is,
>>>
>>> Daniel
>>>
>>
>> What does "again" here mean? as I couldn't find another place which
>> introduce new code. :-)
>
>    Well I would not modify cmdDomblkstat and instead create a new command
> and a new function for the new API
>
>> And per the new API has some same fields with old API, and seems
>> all of virsh commands try to fallback to old API if new API is introduced.
>
>   yes but the new API will provide informations in a different order
> and is potentially more expensive, so I'm not sure I really want to use
> the new API for the old command
>   Maybe something like "domblkfullstat"...
>
>   But if someone else disagrees with me I'm fine being in the minority :-)

Personally, I'd like to keep a single virsh command for both APIs, just 
like 'virsh migrate' handles both virDomainMigrate and 
virDomainMigrate2.  I don't know if it's better to default to the old or 
the new API, but it is easy enough to provide a flag that swaps the 
default to call the alternate API.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org