Re: [Xen-devel] Credit Scheduler not working correct (3.0.4-0)

[Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>]

Hi, Timo

Primary goal of Credit Scheduler is loadbalancing multiple CPU resources.
So if you pin vcpu, this condition is violated,
since vcpu cannot migrate between pcpu.

Anyway, Credit scheduler specification is defined by Emmanuel.
So I have no comment on it.

But, I hope scheduler instruction should be simple.(like vmware weight)
Current credit scheduler is very complex 
when we uses relative weight and vcpu pin with mixing these two parameter)

c.f. vmware uses absolute weight(like CPU freqency)

Thanks
Atsushi SAKAI



Timo Benk <timo.benk@xxxxxx> wrote:

> Atsushi SAKAI wrote:
> > Hi, Timo
> > 
> > If you want to divide CPU resources as you expected,
> > each vcpu weight should be same.
> > In your case, you should define xendom1 for 1vcpu
> > and xendom2 for 2vcpu(s). then after you should pin these vcpus to pcpu0.
> 
> Hm, is that a bug or a feature?
> 
> I thought the crdeit-schedulers primary goal was to avoid this pinning 
> nightmare
> you have with SEDF?
> 
> Greetings,
> -timo
> 
> > Timo Benk <timo.benk@xxxxxx> wrote:
> > 
> >> Hi,
> >>
> >> on my system, it seems that the credit scheduler does not work as 
> >> expected. The
> >> problem seems to be related to HyperThreading, if i switch off HT in the 
> >> BIOS
> >> Setup, the scheduler works as expected.
> >>
> >> I have two domains running, both pinned to the same processor:
> >>
> >> Domain-0:~ # xm vcpu-list
> >> Name                              ID  VCPU   CPU State   Time(s) CPU
> >> Affinity
> >> Domain-0                           0     0     1   ---      30.2 any cpu
> >> Domain-0                           0     1     1   r--      12.0 any cpu
> >> xendom1                            1     0     0   ---      98.6 0
> >> xendom2                            2     0     0   r--     110.3 0
> >>
> >> Both domains should consume max. 100 Percent of that processor, but
> >> xendom1 has a weight twice as big as xendom2:
> >>
> >> Domain-0:~ # xm sched-credit -d xendom1
> >> {'cap': 100, 'weight': 200}
> >> Domain-0:~ # xm sched-credit -d xendom2
> >> {'cap': 100, 'weight': 100}
> >>
> >> In my understanding of the credit scheduler, xendom1 should get twice as
> >> much CPU-time as xendom2. But:
> >>
> >> xentop - 11:05:46   Xen 3.0.4-0
> >> Mem: 2612284k total, 2603852k used, 8432k free    CPUs: 2 @ 2992MHz
> >>       NAME  STATE   CPU(sec) CPU(%)  [...]
> >>   Domain-0 -----r         42    0.6  [...]
> >>    xendom1 ------        122   49.8  [...]
> >>    xendom2 -----r        133   50.2  [...]
> >>
> >> As you can see, both domains got an equal amount of the CPU.
> >>
> >> Am i missing something or do i understand something wrong?
> >>
> >> Greetings,
> >> -timo
> >> -- 
> >> Timo Benk - Jabber ID: fry@xxxxxxxxxxxx - ICQ ID: #414944731
> >> PGP Public Key: http://m28s01.vlinux.de/timo_benk_gpg_key.asc
> >>
> >>
> >> _______________________________________________
> >> Xen-devel mailing list
> >> Xen-devel@xxxxxxxxxxxxxxxxxxx
> >> http://lists.xensource.com/xen-devel
> > 
> > 
> 
> 
> -- 
> Timo Benk - Jabber ID: fry@xxxxxxxxxxxx - ICQ ID: #414944731
> PGP Public Key: http://m28s01.vlinux.de/timo_benk_gpg_key.asc
> 



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