This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


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

On 8 Jun 2005, at 23:18, Ryan Harper wrote:

Let me put it this way: I reserve the right in future to change my mind
and free the vcpu info structures for vcpus that are down (and
re-allocate when they come back up). If I do that then you will not get
info about them via hypercalls. There's no good reason to return info
about them -- you can infer they are 'down'/non-existent from their
absence -- so why bother?

It seemed nicer/easier/cheaper (to me) to mark up/down in the dominfo
hypercall rather than issue MAX_VIRT_CPUS vcpucontext hypercalls.

Setting vcpu_to_cpu[vcpu] to -1 for down vcpus sounds sensible to me. Then you only need to issue vcpucontext calls for vcpus for which vcpu_to_cpu[] >= 0.

If it might also be possible to have vcpus that aren't down, but also aren;t allocated to a cpu right now for some reason, we probably want two invalid values to distinguish the two cases. Perhaps the latter situation doesn't make sense though, in which case we can ignore it.

 -- Kier

Xen-devel mailing list