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Re: [Qemu-devel] IO performance test on the tcm-vhost scsi
From: |
Cong Meng |
Subject: |
Re: [Qemu-devel] IO performance test on the tcm-vhost scsi |
Date: |
Thu, 14 Jun 2012 17:45:22 +0800 |
On Thu, 2012-06-14 at 09:30 +0100, Stefan Hajnoczi wrote:
> On Wed, Jun 13, 2012 at 11:13 AM, mengcong <address@hidden> wrote:
> > seq-read seq-write rand-read rand-write
> > 8k 256k 8k 256k 8k 256k 8k 256k
> > ----------------------------------------------------------------------------
> > bare-metal 67951 69802 67064 67075 1758 29284 1969 26360
> > tcm-vhost-iblock 61501 66575 51775 67872 1011 22533 1851 28216
> > tcm-vhost-pscsi 66479 68191 50873 67547 1008 22523 1818 28304
> > virtio-blk 26284 66737 23373 65735 1724 28962 1805 27774
> > scsi-disk 36013 60289 46222 62527 1663 12992 1804 27670
>
> >
> > unit: KB/s
> > seq-read/write = sequential read/write
> > rand-read/write = random read/write
> > 8k,256k are blocksize of the IO
>
> What strikes me is how virtio-blk performs significantly worse than
> bare metal and tcm_vhost for seq-read/seq-write 8k. The good
> tcm_vhost results suggest that the overhead is not the virtio
> interface itself, since tcm_vhost implements virtio-scsi.
>
> To drill down on the tcm_vhost vs userspace performance gap we need
> virtio-scsi userspace results. QEMU needs to use the same block
> device as the tcm-vhost-iblock benchmark.
>
> Cong: Is it possible to collect the virtio-scsi userspace results
> using the same block device as tcm-vhost-iblock and -drive
> format=raw,aio=native,cache=none?
>
virtio-scsi-raw 43065 69729 52052 67378 1757 29419 2024 28135
qemu ....\
-drive file=/dev/sdb,format=raw,if=none,id=sdb,cache=none,aio=native \
-device virtio-scsi-pci,id=mcbus \
-device scsi-disk,drive=sdb
there is only one scsi HBA.
/dev/sdb is the disk on which all tests have been done.
Is this what you want?
Cong Meng
> Stefan
>