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[Xen-users] Fwd: Re: Windows PV drivers destroying performance

  • To: xen-users@xxxxxxxxxxxxx
  • From: Ghormoon <ghormoon@xxxxxxxxx>
  • Date: Fri, 24 Jul 2015 16:28:12 +0200
  • Delivery-date: Fri, 24 Jul 2015 14:29:22 +0000
  • List-id: Xen user discussion <xen-users.lists.xen.org>

Sorry to Ian, I didn't notice my phone decided to send it as pm only, resending to the list.
> Hi,
> Not sure if this may help, but when I've tried installing pv drivers like a year back and it happened to me, that the windows machine updated at the same time. That went seriosly bad.
> When i've restored older snapshot, updated it, rebooted, installed pv, rebooted again, it went flawlessly. (I've been using rdesktop to access kit most time).
> If you have the option of retrying from snapshot, give it a shot and check. I was not able to fix the machine by uninstalling/reinstalling them back then. Too bad I likely don't have that old log to compare.
> Regards,
> Ghor
> On Jul 24, 2015 3:39 PM, "Ian Campbell" <ian.campbell@xxxxxxxxxx> wrote:
>> On Fri, 2015-07-24 at 22:14 +1000, G Crowe wrote:
>> > I installed the PV drivers in some windows PVs as I thought it would
>> > improve performance, but the systems then became painfully slow to use.
>> >
>> > I ran some tests on hard disc performance on a newly installed Win7 32
>> > bit system before and after installing the PV drivers from univention.de
>> > (version as the other sites appear to be offline. The host
>> > machine is running Fedora 21 with kernel 3.19.3.
>> > Without the PV drivers (with QEMU hardware) hard disc performance was
>> > 4409 I/O per second and 9.03Mbps.
>> > With the PV drivers installed this dropped to 207 I/O per second and
>> > 0.43Mbps.
>> >
>> > Without the PV drivers, the remote desktop screen would refresh almost
>> > instantly, but with the PV drivers it could take up to 10 seconds just
>> > to refresh the screen.
>> >
>> > I don't understand this, as I though that the sole purpose of the PV
>> > drivers was to improve I/O performance,
>> Your expectation here is correct.
>> >Â yet they have made the system so
>> > slow that it is virtually unusable.
>> >
>> > Am I doing something wrong here?
>> It seems unlikely, I don't think there is much you can have done wrong,
>> it's supposed to just work ;-) more likely some sort of bad interaction
>> between some (possibly buggy) component and another.
>> I don't know much about the Windows PV drivers, so hopefully someone else
>> can chip in with some tips/knowledge.
>> Seeing your guest cfg file and any relevant logs from /var/log/xen might
>> have some sort of clue.
>> Ian.
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