Re: [Xen-devel] host information in domU over /proc or /sys filesystem

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> This feature is very important for quality of service aspects. How many
> physical CPU do I have? How many CPU time can I use?

I'm not exactly sure whether a domU needs to know this?  or do you mean dom0 
specifically?

The number of physical CPUs the domain's VCPUs are being scheduled across 
might change dynamically.  You can, however, change the number of VCPUs a 
domain is allocated as an indication of how many CPUs it should try to 
optimise for.  There's also /sys/hypervisor which contains some relevant 
information.

dom0 is permitted to access more detailed information about the host machine 
through a hypercall (use "xm info" to see what's available).

> Other important > information would the real memory and the hostname of the 
host machine.

I'm not sure why a domU would need to know the hostname of the host machine?  
Also, this could change during migration, so it's not a stable value.

Cheers,
Mark

> Basically all this information is provided by other virtualization
> technologies as read only values. Having a huge hosting solution with
> enterprise software running in virtual machines depends on these quality
> of service aspects. Having a black box makes debugging of performance
> issues impossible and thus the whole solution is not usable.
>
> Is it possible to provide such a solution with Xen (of course only if
> enabled in dom0 due to security reasons!) over the /proc or /sysfs?
>
> Thanks,
> Hannes



-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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