RE: [Xen-devel] Is anyone using the credit scheduler "cap" functionality?

["Santos, Jose Renato G" <joserenato.santos@xxxxxx>]

I would add another use for cap.
Sometimes it is usefull to understand how a domain behaves as a function of the 
amount of CPU that is allocated to it. For example when deciding how many 
applications can be consolidated on a server you may want to run some tests 
with specific benchmarks controling the exact amount of CPU allocated to the 
domain running the application. This allow you to predict how a domain will 
behave when the amount of CPU is limited due to sharing the CPU with other 
domain.
The cap is very useful for this scenario. In fact, Rutgers University and HP 
Labs are working on a Research Project (JustRunIt) that uses the CAP 
functionality of the scheduler to test and characterize a domain behavior as a 
function of the allocated CPU.

I would be very disappointed if the CAP functionality was removed from Xen 
scheduler

Renato   

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Dan Magenheimer
> Sent: Tuesday, January 20, 2009 12:33 PM
> To: George Dunlap; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: RE: [Xen-devel] Is anyone using the credit scheduler 
> "cap" functionality?
> 
> IIRC, the cap functionality is useful primarily for 
> application licensing, e.g. to ensure that an app licensed 
> for 2 cpus never gets more than 2 cpus, even if all other 
> cpus are idle.
> I suppose it could also be used by a webhosting provider to 
> create similar limits to allow selling of an added-value tier 
> (e.g. "uncapped", kind of a poor man's cloud computing).
> 
> Given that, I'd say this is a much too restricted forum 
> (primarily developers) to ask and, even if it's not being 
> used today, pulling it out seems premature unless there's a 
> *really* good reason.
> 
> My two cents,
> Dan
> 
> > -----Original Message-----
> > From: George Dunlap [mailto:George.Dunlap@xxxxxxxxxxxxx]
> > Sent: Tuesday, January 20, 2009 12:09 PM
> > To: xen-devel@xxxxxxxxxxxxxxxxxxx
> > Subject: [Xen-devel] Is anyone using the credit scheduler "cap"
> > functionality?
> > 
> > 
> > I'm in the process of revising the credit scheduler design, and I'd 
> > like to know how important it is to maintain the "cap" 
> functionality 
> > of the credit scheduler.  If you use it, or know of someone 
> who does, 
> > could you let me know?
> > 
> > If you don't know what it is, you probably aren't using it. :-)
> > 
> > Peace,
> >  -George
> > 
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> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> >
> 
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