Re: [Xen-devel] xen scheduler question

[Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>]

Hi, Agwal

  Your suggestion is right for typical cases but not guraranteed.
this case should be applied for cpu-intensive jobs.

Typical case is shown as follows.
timeline ---->
pCPUx  Dom1vcpuA Dom1vcpuB
pCPUY  Dom2vcpuC Dom2vcpuC
Typcal credit value is shown as follows
For more detail see the code.(common/sched_credit.c)

Every 30msec recalculate and give the credit to each vcpu.
and account the credit each 10msec.
Dom1vcpuA 15msec  5msec -5msec -15msec| 0msec  0msec  0msec 0msec|
Dom1vcpuB 15msec 15msec 15msec  15msec|30msec 20msec 10msec 0msec|
Dom2vcpuC 30msec 20msec 10msec   0msec|30msec 20msec 10msec 0msec|

Thanks
Atsushi SAKAI



"Agarwal, Lomesh" <lomesh.agarwal@xxxxxxxxx> wrote:

> So that means on one physical CPU domain with one VCPU will run all the
> time while on the other physical CPU VCPUs of other domain will
> alternate. Right?
> Can someone give me timeline of how VCPUs are scheduled on physical CPU.
> Domain 1 - VCPU A and B
> Domain 2 - VCPU C
> Physical CPU X and Y
> 
> -----Original Message-----
> From: Atsushi SAKAI [mailto:sakaia@xxxxxxxxxxxxxx] 
> Sent: Wednesday, January 31, 2007 5:09 PM
> To: Agarwal, Lomesh
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] xen scheduler question
> 
> Hi, Agarwal
> 
> It should be run as you suggested.
> Xen treats weight on domain basis.
> 
> But this situation changes, if you pin to some vcpu to pcpu.
> 
> Thanks
> Atsushi SAKAI
> 
> 
> "Agarwal, Lomesh" <lomesh.agarwal@xxxxxxxxx> wrote:
> 
> > If there are two guest running one with 1 VCPU and other with 2 VCPU
> > with equal weight and no cap on a dual core machine, how will Xen
> assign
> > the physical CPUs to guests? Does Xen treats weight on domain basis?
> If
> > that's true then VCPU of domain with one VCPU will be scheduled twice
> as
> > often then the VCPU of other domain. Right?
> > 
> 
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