Re: [Qemu-devel] Re: [kvm-devel] [PATCH 1/3] Refactor AIO interface to allow other AIO implementations

[Anthony Liguori <aliguori@us.ibm.com>]

Jamie Lokier wrote:
>> I've basically got a choice of making libvirt always ad '-aio linux'
>> or never add it at all. My inclination is to the latter since it is
>> compatible with existing QEMU which has no -aio option. Presumably
>> '-aio linux' is intended to provide some performance benefit so it'd
>> be nice to use it. If we can't express some criteria under which it
>> should be turned on, I can't enable it; where as if you can express
>> some criteria, then QEMU should apply them automatically.
>>     
>
> I'm of the view that '-aio auto' would be a really good option - and
> when it's proven itself, it should be the default.  It could work on
> all QEMU hosts: it would pick synchronous IO when there is nothing else.
>   

Right now, not specifying the -aio option is equivalent to your proposed 
-aio auto.

I guess I should include an info aio to let the user know what type of 
aio they are using.  We can add selection criteria later but 
semantically, not specifying an explicit -aio option allows QEMU to 
choose whichever one it thinks is best.

Regards,

Anthony Liguori