From: Paolo Bonzini <pbonzini@redhat.com>
To: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: target-devel@vger.kernel.org,
Stefan Hajnoczi <stefanha@gmail.com>,
linuxram@us.ibm.com, qemu-devel@nongnu.org,
"Nicholas A. Bellinger" <nab@linux-iscsi.org>,
Cong Meng <mc@linux.vnet.ibm.com>,
Anthony Liguori <anthony@codemonkey.ws>,
Asias He <asias@redhat.com>
Subject: Re: [Qemu-devel] IO performance test on the tcm-vhost scsi
Date: Thu, 14 Jun 2012 14:27:15 +0200 [thread overview]
Message-ID: <4FD9D8A3.1080005@redhat.com> (raw)
In-Reply-To: <20120614120722.GA7128@stefanha-thinkpad.localdomain>
Il 14/06/2012 14:07, Stefan Hajnoczi ha scritto:
> Perfect, thanks. virtio-scsi userspace is much better than virtio-blk
> here. That's unexpected since they both use the QEMU block layer. If
> anything, I would have expected virtio-blk to be faster!
Yes, I would have expected something similar. A blktrace would be
useful here because Asias measured the opposite---virtio-scsi being much
slower than virtio-blk.
> The second question is why is tcm_vhost faster than virtio-scsi
> userspace.
I would expect a difference on more high-end benchmarks (i.e. lots of
I/O to lots of disks), similar to vhost-blk. In this simple case I
wonder how much it is due to the vagaries of the I/O scheduler, or even
statistical noise.
Paolo
next prev parent reply other threads:[~2012-06-14 12:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-13 10:13 [Qemu-devel] IO performance test on the tcm-vhost scsi mengcong
2012-06-13 10:35 ` Stefan Hajnoczi
2012-06-13 19:08 ` Nicholas A. Bellinger
2012-06-14 9:57 ` Cong Meng
2012-06-14 20:41 ` Nicholas A. Bellinger
2012-06-15 10:35 ` Stefan Hajnoczi
2012-06-14 8:30 ` Stefan Hajnoczi
2012-06-14 9:45 ` Cong Meng
2012-06-14 12:07 ` Stefan Hajnoczi
2012-06-14 12:27 ` Paolo Bonzini [this message]
2012-06-14 20:45 ` Nicholas A. Bellinger
2012-06-15 3:28 ` Asias He
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