On Feb 16, 2016, at 7:50 PM, IWAMOTO Toshihiro <[email protected]> wrote:
> With a software switch such as openvswitch, PacketIn events may not
> happen.

That's true; that can *also* be the case with a hardware switch, though.

> And even with your situation, in a interval where there's no pending
> PacketIn event, processing of other high priority events can be
> delayed up to 5 seconds with your code.
> 

OK. Your argument, then, is that the wait-until-timeout on an empty PacketIn 
queue delays processing of higher priority events that may arrive during the 
wait.

That's a fair critique; I need to think about how best to address it.

> I think you can increase the queue size to reduce such priority
> inversions, or independent semaphores can be used to limit the number
> of low priority events in the queue.

Actually - that idea may be the closest to a solution.

How about a single priority queue, of size n, with 3 semaphores of size n/3?
Events are inserted into the queue, in priority order, and consume an 
appropriate semaphore entry upon insertion.
Events are removed from the queue in priority order, and increment the 
appropriate semaphore upon removal.

In that way, there should be no delay in awaiting events, and insertion into 
the priority queue will not be subject to priority inversion.

Best,
Victor
--
Victor J. Orlikowski <> vjo@[cs.]duke.edu


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