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Re: [Xen-devel] [PATCH][RESUBMIT] don't schedule unplugged vcpus

On 8 Jun 2005, at 22:42, Ian Pratt wrote:

I don't see why we care about vcpus that are down. From the user's point
of view they've gone for good -- it just happens that Xen hasn't freed
the memory in anticipation of it being used again. What do you think?

I'd be inclined just to enter '-1' in the vcpu_to_cpu map. BTW: we could
make it an s16 rather than s32 at the same time. I think 32,768 CPUs
should keep be enough for anyone :-)

This is how I view it. We don't free the vcpu structure only because it isn't reference counted. We can only be sure that noone has a reference to the structure when the entire domain's refcnt falls to zero. Given the small amount of memory involved, it's not worth the pain or run-time cost of adding per-vcpu reference counts.

So VCPU_down == invisible outside Xen.

 -- Keir

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