Re: [Xen-devel] How to find out how much cpu time each domain used?

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

On Mon, 2016-07-04 at 20:09 +0000, Amin Fallahi wrote:
> Dear all
> 
> I am modifying credit scheduler and I want to give credit to each
> vcpu based on cpu time which its domain has consumed.
> Suppose:
> credit_fair =((credit_total*sdom->weight)+(weight_total-
> 1))/weight_total
> 
Mind describing what your actual end goal is, and spending a little
more word describing how you were thinking to achieve it?

I see the formula, but I don't understand:
 - what is it that you are trying to improve/achieve? Better fairness, 
   I guess?
 - how do you plan to use such formula, i.e., where in the algorithm 
   you'd put it? Credits are already been burned basing on how much a 
   vcpu executes, is this about how much credits a vcpu is given at 
   the beginning/reset? How would it integrate with credits_per_tslice 
   and friends?

> I want to multiply something to this formula according to the domain
> cpu usage. Thus I need to somehow find out cpu time for each domain.
>
Cpu usage in terms of what? Time? Percentage? Over what time interval?

It is certainly possible to figure out how long a vcpu executed on a
pcpu on a given time interval, but depending from the characteristics
of such time interval, the way to actually do that varies.

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)

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