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Re: [Xen-users] x64 hvm linux very slow on a x64 xen host

To: Pasi Kärkkäinen <pasik@xxxxxx>
Subject: Re: [Xen-users] x64 hvm linux very slow on a x64 xen host
From: Matthieu Patou <mat+Informatique.xen@xxxxxxxxx>
Date: Sat, 23 Jan 2010 01:48:49 +0300
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On 20/01/2010 13:23, Pasi Kärkkäinen wrote:
On Wed, Jan 20, 2010 at 01:06:32PM +0300, Matthieu Patou wrote:
On 20/01/2010 12:47, Pasi Kärkkäinen wrote:
On Wed, Jan 20, 2010 at 11:30:37AM +0300, Matthieu Patou wrote:

Hello,

I'm trying to use Fedora x64 on a xen x64 host in hvm mode and the domU
is _very_ slow.
I am wondering if there is any tunning possible ?


You'd have to pv-on-hvm drivers to get good IO performance.

Where can I get them ?

What Fedora version are you using? What kernel?
So it's an install from the live cd of Fedora 12 x64.
Other (easier) option is to use Fedora PV guest, instead of HVM.


Yeah I'm thinking about converting my image to PV but I was just
wondering why is so slow ...
Note that fedora i386 do not look so slow on the same xen x64 host

Yeah that's weird..

Did you measure Xen cpu usage with "xm top" in dom0?

Not yet i'll retry soon. I'll let you know.
What's using the CPU?
Is there any load on dom0? Check with "top".

How did you measure the HVM guest is slow?

Because compiling samba 4 in this host takes ages although in fedora 386 with the same code the speed is way better.

Matthieu.

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