[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-users] [Xen-devel] Cannot Start Linux Paravirtualized (PV) Guests with Xen 4.2-unstable

On 30/03/2012 05:09, Sergey Zhukov wrote:
3) When I was installing Ubuntu 12.04 Beta 1 Precise Pangolin amd64 as
a HVM domU in either Xen 4.1.3-rc1-pre or Xen 4.2-unstable, it hanged
at COPYING FILES during installation. Hence I have to abort the HVM
domU installation. Disk I/O performance is very poor.
4) Disk I/O performance is very poor with Debian 6.0 Squeeze PV domU
in Xen 4.2-unstable and with Fedora 16 x86-64 PV domU in Xen
4.1.3-rc1-pre. The mouse cursor movement in both Fedora 16 and Debian
6.0 Squeeze PV domU is very sluggish and unresponsive. It also takes a
long time to format filesystems and install packages in PV domU during
OS installation. What causes the performance penalty in disk I/O?
5) Disk I/O performance is also very poor with Ubuntu 12.04 Beta 1 HVM
domU installation. Formatting filesystems and copying files during
installation take a long time. Mouse cursor movement is also very
I installed Ubuntu 12.04 beta server (AMD 64) and xen hypervisor from
ubuntu xen packages (v4.1).
Then I installed Ubuntu 10.04 server as PV DomU and Ubuntu 10.04 desktop
as HVM DomU.
I could not enable IO virtualization, because iommu=1 and iommu=verbose
parameters seem to be not working.
Dear Sergey Zhukou,

Thank you very much for your reply.

I did not have to specify IOMMU=1 and IOMMU=verbose in my multiboot xen.gz command line in GRUB2. IOMMU is enabled by default in Xen 4.2-unstable.

sudo xl dmesg | grep 'I/O Virtualisation'

(XEN) I/O Virtualisation Enabled

When I run tests for my specific software I found, that in Ubuntu 10.04
HVM DomU there are too many interrupts when dealing with network.
Processor took about 50%si. I did not test disk IO, but think the
picture should be the same.

When I am installing Ubuntu 12.04 Beta 1 HVM domU, the network connection gets disconnected and re-connected many times. Did your installation hanged at copying files while installing Ubuntu 10.04 HVM domU?

But I found solution, which works perfect for me. I installed Ubuntu
12.04 desktop beta (i386) as PVHVM DomU. It installed without hangs and
it works very fast with network and disk.

I do not know what is PVHVM, I only know PV domU and HVM domU separately.

Only one thing looks ugly: I can't change maximal resolution of the
desktop more than 1024x768 (despite of settings stdvga=1 and

Also, I would like to know, how to enable verbose logs for iommu,
because xm dmesg does not show me any information about VT-d. I have the
(XEN) Command line: placeholder iommu=verbose
in the dmesg logs, but still not got verbose logs...

I do not know how to enable verbose logs for IOMMU.

Have you tried "sudo xl dmesg | grep VT-d"?

Sergey Zhukov

Yours sincerely,

Mr. Teo En Ming (Zhang Enming)

Xen-users mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.