Re: [Qemu-block] [PATCH v5 17/38] block: Add BlockBackendRootState

[Alberto Garcia]

On Tue 22 Sep 2015 05:00:05 PM CEST, Max Reitz wrote:

>> The correct way to solve this seems to be that each BB has its own
>> I/O throttling filter. Actually, if we could lift the throttling code
>> to BlockBackend, that might solve the problem.
>
> So yes, as long as we have throttling on the BDS level, something may
> always break when having multiple BBs per BDS, because you'd probably
> want throttling to be on the BB level. But lifting that doesn't seem a
> trivial task, and I don't really know whether I want this in this
> series.
>
> Especially considering that right now you cannot have multiple BBs per
> BDS.
>
> All in all: Yes, before we allow multiple BBs per BDS we want
> throttling to be on the BB level. But this is nothing that should be
> done in or for this series, since right now we do not allow multiple
> BBs per BDS.

I agree that it makes sense to move throttling to the BB level. It's
probably not trivial but I don't think it's too complex either. I can
give it a look once this series has been merged.

Berto