Re: SpeedStep in DomUs?

[Jean-Yves Migeon <jeanyves.migeon%free.fr@localhost>]

On 12.07.2010 00:33, Stefan Groà wrote:
> Ok, thanks, but that is not my problem (perhaps my bad english, sorry) I
> know how to do the sysctl-things, but i don't get the vcpus of dom0
> pinned to the real cpus. And if i manage to do as they say in the wiki (
> http://wiki.xensource.com/xenwiki/xenpm ):
> 
> "Domain0 based cpufreq has one limitations, i.e. domain0 VCPU number
> must be the same as the number of physical CPUs, and the domain0 VCPU
> must be pinned to physical CPU"
> 
> that is: pin all cpus to dom0, how can i still run my domUs? Perhaps i'm
> just not informed enough.

Pinning just tells the hypervisor to not move virtual CPU context away
from a given physical CPU. It will not prevent other domains from
running, it just means that, when one domain is scheduled for execution,
the context used for a given vcpu will only run on the physical it is
pinned to.

> What i tried now is: boot-options: "dom0_vcpus_pin cpufreq=dom0-kernel"
> -- according to "xm dmesg" the "dom0_max_cpus" is already set to 4 (i
> have 4 cpus). I don't know how to set the exact number of cpus (opposed
> to max number), and I don't know if i can still run domUs if i pin all
> real cpus to the dom0, and i don't know how to do the pinning.

Pinning is done through xm(1): $ xm vcpu-pin 0 all 0

NetBSD dom0 is not multi CPU capable, so there is only one CPU running.

> With the boot-options i tried a "sysctl -a|grep est" gives nothing, dom0
> has 1 vcpu according to "xm list" and according to "cpuctl identify 0"
> this cpu (=vcpu) does not support EST. But the physical cpus do, with a
> native NetBSD-Installation.
> So here my questions:
> - How to pin all pysical cpus to dom0?

xm vcpu-pin 0 all 0

(this would pin all dom0 VCPU to physical CPU 0)

> - If i do, can i still run domUs?

yes

> - or am i completely missunderstanding something?

Nope.

-- 
Jean-Yves Migeon
jeanyves.migeon%free.fr@localhost