Re: xenpm and scheduler

[Dario Faggioli <dario.faggioli@citrix.com>]

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On Tue, 2016-04-12 at 17:46 +0000, tutu sky wrote:
> yeah, running xenpm gives short comments on its commands and their
> options but not about how to establish it.
> 
I do not understand what you mean with 'establishing' xenpm. If you run
Xen on a machine that has power management and/or frequency scaling
capabilities, you'll be able to use the various xenpm commands.

It most likely will have to be a real hardware box, as I don't think
emulation or nested virtualization satisfies the above condition (for
most of the emulator and hypervisor that I know of). You also need to
use a sufficiently recent Linux dom0 kernel. Konrad knows better than
me what's the minimum necessary version, but I don't think this is a
problem (i.e., any kernel since the last couple of years should work
fine).

Or was it something else you were asking?

Dario

> I try my best for this :)
> thanks a lot.
> 
> ________________________________________
> From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Sent: Tuesday, April 12, 2016 5:08 PM
> To: tutu sky
> Cc: Dario Faggioli; Meng Xu; Xen-devel@lists.xen.org
> Subject: Re: [Xen-devel] xenpm and scheduler
> 
> On Tue, Apr 12, 2016 at 05:04:04PM +0000, tutu sky wrote:
> > 
> > Thanks Konrad. I will do :)
> > Yeah, I believe so. as i can see that there is not any bios
> > settings for power management in there (vmware).  I hope you be the
> > correct party which i want to ask this question: there is a
> > tutorial here in this page:
> > 1) http://xenserver.org/partners/developing-products-for-xenserver/
> > 19-dev-help/138-xs-dev-perf-turbo.html
> > 
> > which i know as a quick guide for establishing xenpm. my Q is that,
> > are this page and this two page of xen.wiki below enough for
> > establishing xenpm and make it work totally?
> > 
> > 2) http://wiki.xenproject.org/wiki/Xenpm_command
> > 3) http://wiki.xenproject.org/wiki/Xen_power_management
> > 
> >  if yes, there is a problem, when i compiled xen from source, there
> > is not any xensource folder in /opt folder in dom0 to follow the
> > instructions in (1) address. i did all those instructions in dom0
> > config file instead.
> Xen source != XenServer.
> 
> 
> > 
> > 
> > if these guides are not enough in your point of view too, i think
> > (just as a suggestion), xenpm needs more documentation, in order to
> > clarify it's activation and usage progress. it remains a silent
> > area in this giant project although is quiet usable.
> > 
> If you run 'xenpm' by itself it gives you the options.
> 
> Patches to make an manpage for xenpm are always warmly welcome!
> > 
> > thanks and regards.
> > 
> > ________________________________________
> > From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > Sent: Tuesday, April 12, 2016 1:41 PM
> > To: tutu sky
> > Cc: Dario Faggioli; Meng Xu; Xen-devel@lists.xen.org
> > Subject: Re: [Xen-devel] xenpm and scheduler
> > 
> > On Tue, Apr 12, 2016 at 11:50:42AM +0000, tutu sky wrote:
> > > 
> > > 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.
> > You will have to.
> > 
> > I don't believe VMWare exposes C and P states to guests so
> > therefore
> > there is no power freqeuency in play.
> > 
> > > 
> > > regards.
> > > ________________________________________
> > > From: Dario Faggioli <dario.faggioli@citrix.com>
> > > Sent: Tuesday, April 12, 2016 8:10 AM
> > > To: tutu sky; Meng Xu
> > > Cc: Xen-devel@lists.xen.org
> > > 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)
> > > 
> > > 
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@lists.xen.org
> > > http://lists.xen.org/xen-devel
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
-- 
<<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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