Re: [Xen-devel] another scheduler problem, on x86_64 only?

[Stephan Diestelhorst <sd386@xxxxxxxxxxxx>]

Just for clarification:
   Andrew: Which scheduler did you use? sedf? or bvt?
   Jun: did you try the bvt scheduler too?

Stephan
> Andrew Theurer wrote:
> > I Noticed that dom0 is only getting about 50% cpu after seeing about
> > 1/2 the performance on some benchmarks, xen0 vs baremetal.  I just
> > ran a quick cpu bound script:
> >
> > while [ 1 ]; do x=1; done&
> >
> > ..and I get this cpu util:
> >
> >     total   domains
> >     ------- ----------
> >  cpu0:  [050.7] d0-0[050.7]
> >
> >  cpu0:  [049.8] d0-0[049.8]
> >
> >  cpu0:  [049.8] d0-0[049.8]
> >
> >  cpu0:  [049.8] d0-0[049.8]
> >
> >
> > Anyone else seen this on x86_64 dom0 with BVT?
>
> I also see this problem. For example, if I run lmbench on dom0, I used
> to see almost 100% CPU load, but it's clearly limited to <= 50% (and
> performance is bad). This stared to happen when the default scheduler is
> switched to sedf. I also tried various parameters with sedf, the results
> were basically same, i.e. never got > 50%. To me it looks like the
> scheduler is always giving 50% CPU cycles to the idle domain(?)
> regardless of the scheduling policy.
>
> > I do not see this in i386 with BVT.
>
> So maybe it assumes that the guest kernels run in ring1.
>
> > [root@e326-1 src]# xm dmesg | grep sched
> > (XEN) Using scheduler: Borrowed Virtual Time (bvt)
> >
> > [root@e326-1 src]# xm dmesg | grep -i changeset
> >  Latest ChangeSet: Tue Jul 12 08:19:10 2005
> > 9f6057761c8f485b1948fdd3308ae10e3ea66ad5
> >
> >
> > -Andrew
>
> Jun
> ---
> Intel Open Source Technology Center
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel