Re: Virtio and WinXP (disk drivers)

[Dor Laor <dlaor@redhat.com>]

Alpár Török wrote:
> Hi,
>
> First of all please allow me to salute the community since this is my
> first post.
>   
Congratulations, hoping for the next ones :)
> Now my problem. I have been using KVM to conduct tests for various
> software  on windows, so far it worked out just fine. I use savevm and
> loadvm to assure that the VM is in the same state for each test. I do
> a savevm manually, then start the automatic tests.
>
> Lately i was trying to optimize parts of my tests, to increase the throughput.
>
> First the network I/O was slow with the default device, and i needed
> to copy some files to the VM for each test. The virtio network driver
> was fast, but with my bridge networking, on Win XP, after starting the
> VM with loadvm. This isn't such a big issue since i then started using
> e1000 device, and speed increased. I am not sure just how much would
> virtio be faster, so the question remains : Doesn't virtio work with
> loadvm/savevm, or (most probably) am i doing something wrong?
>   
Indeed virtio performs better than e1000.
It should work, please provide host kernel version, kvm version, virtio 
net version and
windows guest type. Also the cmdline and monitor command will help.

> The second issue, even a greather one, is disk access speed in the VM.
> Again i have looked at virtio, but it seems that there is no Win
> direver. Is that so? What can i do to improove disk access
> performance?
>
>   
We have beta code for windows pv block. We plan to publish them as soon
they will be rock stable. Scsi emulation also exist but might not be 
100% stable.
> The final issue isn't related to performance. With the e1000 device,
> accessing or writing files  on a samba share from the host failes
> saying that the file doesn't exists, (the file exists, i am sure).
> This doesn't happen all that often, less than 1% of the time, but it's
> rather anolying because it influences the tests. it seems to be happen
> randomly, i caoudm't identify a factor that might be causing it.
>
>   
Seems like a samba related bug and not necessarily network bug.
> Thank you in advance for your advices.
>
> --
> Alpar Torok
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