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

[Ryan Harper <ryanh@us.ibm.com>]

* Keir Fraser <Keir.Fraser@cl.cam.ac.uk> [2005-06-08 17:07]:
> 
> On 8 Jun 2005, at 23:00, Ryan Harper wrote:
> 
> >So, when I trigger a vcpu to go down via dom0 xm operation, I have to
> >trust that it worked?  I have no way of knowing at some point later
> >which vcpus are up or down?  I don't see any cost to this other than
> >during the getdominfo hcall.
> 
> The ones you can retrieve info about are up. The ones you can't, are 
> down. :-)

Indeed. =)

> 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.  

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh@us.ibm.com