[Qemu-devel] is it possible to use a disk with multiple iothreads ?

[Alexandre DERUMIER]

Hi, 
I was reading this interesting presentation, 

http://vmsplice.net/~stefan/stefanha-kvm-forum-2014.pdf 

and I have a specific question.


I'm currently evaluate ceph/rbd storage performance through qemu,

and the current bottleneck seem to be the cpu usage of the iothread.
(rbd procotol cpu usage is really huge).

Currently It's around 10000iops on 1core of recent xeons.



So, I had tried with virtio-scsi multiqueue, but it doesn't help. (Not sure, 
but I think that all queues are mapped on 1 iothread ?)

I had tried with with virtio-blk and iothread/dataplane, it's help a little , 
but not too much too.

So, my question is : Is it possible to use multiple iothreads with 1 disk ?

(something like 1 queue - 1 iothread?)


Regards,

Alexandre