Re: pvUSB backend performance

[Juergen Gross <jgross@suse.com>]

On 06/29/2015 03:46 PM, David Vrabel wrote:
> On 24/06/15 13:06, Juergen Gross wrote:
>> Hi,
>>
>> my qemu integrated pvUSB backend is now running stable enough to do
>> some basic performance measurements. I've passed a memory-stick with
>> about 90MB of data on it to a pv-domU. Then I read all the data on
>> it with tar and looked how long this would take (elapsed time):
>>
>> in dom0:                     5.2s
>> in domU with kernel backend: 6.1s
>> in domU with qemu backend:   8.2s
>>
>> So the qemu backend is about 30% slower than the kernel backend. Is
>> this acceptable?
>
> Yes?  Maybe? I assume you're adding this backend for a reason, so is it
> good enough for your workloads?

We (SUSE) have a kernel based backend in SLE and openSUSE. I'm pretty
sure it isn't used for really performance critical stuff right now. But
having an upstream variant might change this, so I'd rather ask before
adding the qemu variant and having to do the kernel solution afterwards
as well. :-)

> IMO, It seems a reasonable trade off to not have a bunch of kernel code.

Yeah, this would be my gut feeling, too.


Juergen