RE: [Xen-devel] Re: IDLE domain is scheduled more than dom0

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> > cpu0:  [075.3] d0-0[075.3]
> > cpu1:  [075.3] d0-1[075.3]
> > cpu2:  [075.3] d0-2[075.3]
> > cpu3:  [074.8] d0-3[074.8]
> >  
> >
> This is the current default behaviour of domain 0, it gets 
> 75% of the CPU time and no slack time. This is easily 
> changeable, and I guess it is usefull to do so!

All domains should certainly be eligible for slack time by default
otherwise we'll just confuse people. 

If there are parameter tweaks that help dom0 work better as an IO domain
that's fine, but we should at least it make work as expected for
computer bound stuff too (not that people should really be doing such
stuff in dom0..)

[I suspect most people are only interested in using the weight parameter
rather than setting actual gurantees anyhow] 

I suspect the logic behind giving dom0 a large guarantee is that it that
when it blocks (which it will frequently) its large guarantee will
likely cause it to be scheduled immediately it unblocks, which is
"often" good for IO (not always, as promoting batching may be better in
other circumstances).

We need to get more benchmark numbers that compare sedf and bvt under
more realistic workloads. I'll be particularly interested in reaim and
kernel build numbers.

Stephan: please can you post a fix to the default parameters.

Thanks,
Ian

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