Emmanuel,
The Xen-CIM team has a requirement that we should be able to remove
PCPUs from the scheduling pool. I quote..
* Support for ResourcePoolConfigurationService on some pool types,
e.g. ProcessorPool.This functionality will support for example
removing PCPUs from the pool and dedicate to management domain, thus
restricting set of PCPUs available for consumption by VMs. Does xen
support
this? Can we mask PCPUs such that they are not available to VMs?
End quote.
What needs to be done to add this functionality to the current
scheduler?
Alternately, since you mentioned that vcpu-pinning is not-soft, is it
possible that if we ran a dummy VM that was pinned to the pcpus, we
could do something so we would not be preempted (that would keep those
pcpus from being released into the general scheduling pool)? Is that
even possible? Or would it be more complicated than merely patching the
scheduler and providing a path to doing it via xend?
VCPU affinity should not be soft. By the time the set
affinity hypercall returns, the VCPU in question should be
running on a physical CPU set in its affinity mask.
Thanks
Raj