Re: [Xen-devel] xenpm and scheduler

[tutu sky <ooohooo_u@xxxxxxxxxxx>]

Thanks Dario,
Yeah, I do like playing with xenpm and try understanding relationship between 
this and scheduler. but i established a xen environment on vmware, but xenpm 
does not work correctly and even for 'cpufreq', it is silent at all! so it does 
not let me try to play with :(. I asked this problem before in the user and 
devel lists both,  but no body answered me. how can i track the problem, from 
who (I know that power management is out of your maintenance scope)?? (may 
xenpm have the same problem on a real platform (again) instead of vmware?)
thanks a lot.
regards.
________________________________________
From: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
Sent: Tuesday, April 12, 2016 8:10 AM
To: tutu sky; Meng Xu
Cc: Xen-devel@xxxxxxxxxxxxx
Subject: Re: [Xen-devel] xenpm and scheduler

On Tue, 2016-04-12 at 03:52 +0000, tutu sky wrote:
> Thanks Xu. I will do as desired about cross messaging.
>
> i need it because i exactly want to know that which part of the
> scheduler's corde (credit), takes effect from this feature. because
> it is important to me knowing that where would be trade off between
> idle state and doing load balancing, while cpuidle feature is
> activated. in other side it's important again for me that what will
> happen for 'cap; and 'weight' decreasing in a case that one core's
> frequency is lower than another one in the same socket (actually when
> cpufreq feature is enable).
>
Currently, there is no interaction between the scheduler and the power
management and frequency scaling layers.

> Am i clear enough? can you give me an answer or maybe some lines of
> schedule.c or sched_credit.c's code which i can track them to notice
> the effect of xenpm on scheduler part of the view?
>
If you're saying that, for instance, the CPUs changing frequency can or
should affect some aspects of the scheduling algorithms (like credits
burning rate in Credit1 and Credit2, and budget burning rate in RTDS),
that is an interesting point which may indeed make sense, or at least
would deserve more investigation.

But again, right now, there's no line of code to read to understand the
relationship, as there's no relationship at all.

If you want to experiment on playing with xenpm, and seeing what effect
it has on scheduling, that will be very welcome. :-)

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


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