On 01/04/2011 12:08 PM, Peter Zijlstra wrote:
On Wed, 2011-01-05 at 00:51 +0800, Hillf Danton wrote:
Where is the yield_to callback in the patch for RT schedule class?
If @p is RT, what could you do?
RT guests are a pipe dream, you first need to get the hypervisor (kvm in
this case) to be RT, which it isn't. Then you either need to very
statically set-up the host and the guest scheduling constraints (not
possible with RR/FIFO) or have a complete paravirt RT scheduler which
communicates its requirements to the host.
There's a limited use case.
One host can have a few RT guests, say a host with 8 CPUs
can have up to 6 or 7 RT VCPUs. Those guests get top
priority.
The host can then have some other, low priority, guests
that scavenge remaining CPU time.
In this case, no yield_to is required for RT guests,
because they do not do overcommit.
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