On Tue, 2015-12-01 at 11:59 -0500, Paolo Bonzini wrote:

quoted

What do you think about virtio-nvme+vhost-nvme?

What would be the advantage over virtio-blk?  Multiqueue is not supported
by QEMU but it's already supported by Linux (commit 6a27b656fc).

I expect performance would be better.

Seems google cloud VM uses both nvme and virtio-scsi. Not sure if
virtio-blk is also used.
https://cloud.google.com/compute/docs/disks/local-ssd#runscript

To me, the advantage of nvme is that it provides more than decent performance on
unmodified Windows guests, and thanks to your vendor extension can be used
on Linux as well with speeds comparable to virtio-blk.  So it's potentially
a very good choice for a cloud provider that wants to support Windows guests
(together with e.g. a fast SAS emulated controller to replace virtio-scsi,
and emulated igb or ixgbe to replace virtio-net).

vhost-nvme patches are learned from rts-megasas, which could possibly be
a fast SAS emulated controller.
https://github.com/Datera/rts-megasas

Which features are supported by NVMe and not virtio-blk?

Rob (CCed),

Would you share whether google uses any NVMe specific feature?

Thanks.