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Re: [Xen-users] HVM on 3.2 kernel hdd speed issue

On 04/02/2012 01:55 PM, Heiko Wundram wrote:
Am 02.04.2012 13:33, schrieb Mario:
On 04/02/2012 12:19 PM, Heiko Wundram wrote:
Windows, of course, does not natively support PVonHVM in any way (except
when using corresponding drivers to enable that), so if you get
excessively slower I/O-speeds on "fully" virtualized Linux DomUs than
you do on Windows DomUs which _don't_ have the corresponding PV-drivers
installed, something else is amiss here; it'd help if you could describe
your setup in a little more detail.

Why are we still on PVonHVM subject? I do not want that, I want
regular HVM to work with linux domU's the same way it works with
windows domU's. I don't have the luxury to install custom drivers on
some domU's, so there is no point in trying to force me to use PVonHVM
because i can't.
So, anyone else please? :-)

Read my last paragraph again, please: Linux fully virtualized DomUs
(which use the corresponding NIC and disk emulation as implemented by
qemu) shouldn't perform any different than a Windows DomU,
I/O-performance wise, as both of them use the same infrastructure in
Dom0 to do I/O (qemu process). You're saying that they are different,
I/O-wise, so: please be a little more concrete _what_ the problem is
that you're seeing. We don't have crystal balls handy, sorry.

Its actualy quite simple, here is an example: Windows hvm domU disk io on my test server is ~60MB/s (sequential read or write). Linux HVM guests (using same config file template) on the same server gives ~10MB/s (sequential read or write), i tried pretty much everything, from tuning scheduler to changing kernel. I am not sure what to do with it, other then roll back to kernel 2.6.34 on my dom0.

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