Re: How to setup low CPU priority domU

Dario Faggioli
Thu, 26 Sep 2013 08:06:20 -0000

On mar, 2013-09-24 at 09:57 +0200, Jan Hejl wrote:
> Hello everyone,
>
Hi,

> i would like to use one of my domU with all 32 hardware cores but
> with lower priority (something like nice 10), but setting cpu weight
> seems to be someway unstable.
>
You mean you want that domU to have 32 vCPUs? Can I ask you from where
this requirement comes from?

> Dom0 is Gentoo with Xen 4.3.0, 2 AMD Opetrons 6274 (32 cores), 64GB of
> memory, but dom0 runs on 16 cores and 32GB of memory. Hosts 5 linux
> domUs with similiar configs, each from 2 to 4 cores, from 1GB to 4GB of
> memory. DomU with all cores is Windows Server 2008R2 Enterprise with
> Terminal Services installed.
>
Mmm... nice setup! :-P

Do you mind sending here the output of the following commands, to help
us picture the situation better?

~# xl info -n
~# xl list -n
~# xl vcpu-list

If possible, run the following two too:

~# xl debug-key u
~# xl dmesg > xl-dmesg.log

And attach the xl-dmesg.log file.

Of course, do all the above with all your domains up and running, and
after the re-weighting of the Win server.

> When I set cpu-weight to 192 (others have 256 - default), it starts to
> lag. Applications became pretty slow and unstable.
>
You mean apps inside the Win server with 32 vCPUs or in general?

Regards,
Dario

--
<<This happens because I choose it to happen!>> (Raistlin Majere)
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Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)