[Qemu-devel] poor virtio-scsi performance (fio testing)

[Vasiliy Tolstov]

I'm test virtio-scsi on various kernels (with and without scsi-mq)
with deadline io scheduler (best performance). I'm test with lvm thin
volume and with sheepdog storage. Data goes to ssd that have on host
system is about 30K iops.
When i'm test via fio
[randrw]
blocksize=4k
filename=/dev/sdb
rw=randrw
direct=1
buffered=0
ioengine=libaio
iodepth=32
group_reporting
numjobs=10
runtime=600


I'm always stuck at 11K-12K iops with sheepdog or with lvm.
When i'm switch to virtio-blk and enable data-plane i'm get around 16K iops.
I'm try to enable virtio-scsi-data-plane but may be miss something
(get around 13K iops)
I'm use libvirt 1.2.16 and qemu 2.4.1

What can i do to get near 20K-25K iops?

(qemu testing drive have cache=none io=native)

-- 
Vasiliy Tolstov,
e-mail: address@hidden