Re: [Xen-devel] Fwd: [v3 14/15] Update Posted-Interrupts Descriptor during vCPU scheduling

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Thu, Jul 9, 2015 at 12:19 PM, George Dunlap
<George.Dunlap@xxxxxxxxxxxxx> wrote:
> On Thu, Jul 9, 2015 at 4:09 AM, Wu, Feng <feng.wu@xxxxxxxxx> wrote:
>>> That does not necessarily means "we need to do something" in
>>> vcpu_runstate_change(). Actually, that's exactly what I'm asking: can
>>> you check whether this thing that you need doing can be done somewhere
>>> else than in vcpu_runstaete_change() ?
>>
>> Why do you think vcpu_runstaete_change() is not the right place to do this?
>
> Because what the vcpu_runstate_change() function does at the moment is
> *update the vcpu runstate variable*.  It doesn't actually change the
> runstate -- the runstate is changed in the various bits of code that
> call it; and it's not designed to be a generic place to put hooks on
> the runstate changing.

At first glance vcpu_urgent_count_update() might be seen as such a
hook; but the key here is that vcpu_urgent_count_update() is mainly
updating the is_urgent flag *of the vcpu* based on the various
scheduler-related flags.  In that sense it's doing exactly what
vcpu_runstate_change() is doing.

 -George

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