Re: [Xen-devel] (v2) VT-d Posted-interrupt (PI) design for XEN

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.03.15 at 09:14, <feng.wu@xxxxxxxxx> wrote:
>> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: Thursday, March 19, 2015 5:57 PM
>> >>> On 18.03.15 at 13:44, <feng.wu@xxxxxxxxx> wrote:
>> > Here are what we do for the blocked vCPU:
>> > 1. Define a per-cpu list 'blocked_vcpu_on_cpu', which stored the blocked
>> > vCPU on the pCPU.
>> > 2. When the vCPU's state is changed to RUNSTATE_blocked, insert the vCPU
>> > to the per-cpu list belonging to the pCPU it was running.
>> > 3. When the vCPU is unblocked, remove the vCPU from the related pCPU list.
>> 
>> And this works transparently not only with the generic scheduler
>> code moving the vCPU to another pCPU, but also with some of the
>> individual scheduler implementations doing such re-assignments?
> 
> I cannot quite understand this, could you please elaborate a bit more. 

There are multiple places where v->processor can get changed for a
particular vCPU, and obviously all of these need to be taken care of.
Yet a change like the one to come here would normally not be
expected to touch specific schedulers' code, and hence suitably
abstracting this may need some extra thought.

Jan


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