On 09/25/2009 12:07 AM, Dor Laor wrote:
On 09/24/2009 11:59 PM, Javier Guerra wrote:
On Thu, Sep 24, 2009 at 3:38 PM, Kenni Lund<kenni@xxxxxxx> wrote:
I've done some benchmarking with the drivers on Windows XP SP3 32bit,
but it seems like using the VirtIO drivers are slower than the IDE
drivers in
(almost) all cases. Perhaps I've missed something or does the driver
still
need optimization?
very interesting!
it seems that IDE wins on all the performance numbers, but VirtIO
always has lower CPU utilization. i guess this is guest CPU %, right?
it would also be interesting to compare the CPU usage from the host
point of view, since a lower 'off-guest' CPU usage is very important
for scaling to many guests doing I/O.
Can you re-try it with setting the host ioscheduler to deadline?
Virtio backend (thread pool) is sensitive for it.
These drivers are mainly tweaked for win2k3 and win2k8. We once had
queue depth settings in the driver, not sure we still have it, Vadim,
can you add more info?
Also virtio should provide IO parallelism as opposed to IDE. I don't
think your test test it. Virtio can provide more virtual drives than
the max 4 that ide offers.
Dor
Windows XP 32-bit virtio block driver was created from our mainline code
almost for fun.
Not like our mainline code, which is STORPORT oriented, it is a SCSIPORT
(!!!!) mini-port driver.
SCSIPORT has never been known as I/O optimized storage stack.
SCSIPORT architecture is almost dead officially.
Windows XP 32-bit has no support for STORPORT or virtual storage stack.
Developing monolithic disk driver, which will sit right on top of
virtio-blk PCI device, looks like the one way
to have some kind of high throughput storage for Windows XP 32-bit.
Regards,
Vadim.
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