Thanks Stefan for your reply and guidance!
We spent some time on exploring the multiple I/O Threads approach per your
feedback. Based on the perf measurement data, we did see some IOPS improvement
for multiple volumes, which is great. :)
In addition, IOPS for single Volume will still be a bottleneck, it seems like
multiqueue block layer feature which Paolo is working on may be able to help
improving the IOPS for single volume.
@Paolo, @Stefan,
Would you mind sharing the multiqueue feature code branch with us? So that we
could get some rough idea about this feature and maybe start doing some
exploration?
Thanks a lot!
Wei
On 3/5/19, 9:29 AM, "Stefan Hajnoczi" <stefa...@redhat.com> wrote:
On Mon, Mar 04, 2019 at 09:33:26AM -0800, Wei Li wrote:
> While @Stefan mentioned about additional iothread object support of
virtio-blk, Is the feature also supported by virtio-scsi? I am trying to
exploring the perf multiple IO threads / per VM via followings:
> QMP setup example to create 2 io threads in QEMU, one io thread per
device:
>
> (QEMU) object-add qom-type=iothread id=iothread0
>
> (QEMU) object-add qom-type=iothread id=iothread1
>
>
>
> (QEMU) device_add driver=virtio-scsi-pci id=test0 iothread=iothread0
>
> (QEMU) device_add driver=virtio-scsi-pci id=test1 iothread=iothread1
>
>
>
> (QEMU) device_add driver=scsi-block drive=none0 id=v0 bus=test0.0
>
> (QEMU) device_add driver=scsi-block drive=none1 id=v1 bus=test1.0
Yes, each virtio-scsi-pci device can be assigned to an iothread.
> You mentioned about the multi-queue devices feature, it seems like the
multi-queue feature will help improve the IOPS of single Device. Could you
please provide more details?
> What’s the current plan of support multi-queue device? Which release will
include the support or it has already been included in any existing release
newer than 2.9?
> Is there any feature branch which I would get more details about the code
and in progress status?
I have CCed Paolo, who has worked on multiqueue block layer support in
QEMU. This feature is not yet complete.
The virtio-scsi device also supports multiqueue, but the QEMU block
layer will still be a single queue.
Stefan
