[Users] Horrid performance during disk I/O

[Blaster]

I finally found time to switch from virtio-scsi to virtio.  Seems to have make a big difference.

The windows VMs boot faster, web pages load faster, same with the Fedora 20 VMs. 
Everything just feels smoother.

I found this interesting presentation:
http://events.linuxfoundation.org/sites/events/files/slides/CloudOpen2013_Khoa_Huynh_v3.pdf

Claims virtio blk and scsi are the same speed.  Although, it doesn’t mention if this was with or without data plane enabled.

When will data plane be the default?


On Jan 15, 2014, at 3:11 AM, Sander Grendelman <sander at grendelman.com> wrote:

> On Tue, Jan 14, 2014 at 10:38 PM, Blaster <Blaster at 556nato.com> wrote:
>> On 1/14/2014 11:04 AM, Andrew Cathrow wrote:
>>> 
>>> Did you compare virtio-block to virto-scsi, the former will likely
>>> outperform the latter.
>> 
>> 
>> No, but I have been meaning to, out of curiosity.
>> 
>> But why do you say virto-blk will be faster than virtio-scsi?  The
>> virtio-scsi wiki claims equal performance.
> That's also what I read but ... this presentation:
> http://www.linux-kvm.org/wiki/images/f/f9/2012-forum-virtio-blk-performance-improvement.pdf
> claims
> claims: "virtio-blk is about ~3 times faster than virtio-scsi in my setup" o_O
> So testing is definitely a good idea.
>> 
>> I've been trying to get some real numbers of the performance differences
>> using iozone, but the numbers are all over the place, both on the HV and the
>> guests, so not very meaningful.   Not an iozone expert, so still trying to
>> figure out what I'm doing wrong there as well.
> 
> I've also done some (relatively simple) testing with fio.

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