[REVIEW/TEST] polling(4) changes

[dima]

> d> The loop body should really look like
> d>   if( mtx_try_lock( &iface_lock[i] ) ) {
> d>     pr[i].handler( pr[i].ifp, POLL_ONLY, count );
> d>     mtx_unlock( &iface_lock[i] );
> d>   }
> d> I skipped this first to make the idea clearer.
> 
> Yes, this approach should be better.
> 
> d> > Really we do not have several kernel threads in polling. netisr_poll() is always
> d> > run by one thread - swi1:net. Well, we have also idle_poll thread, but it is
> d> > very special case. Frankly speaking, it can't work without help from netisr_poll().
> d> > The current polling is designed for a single threaded kernel, for RELENG_4. We
> d> > can't achieve parallelization with strong redesign. The future plans are to create
> d> > per-interface CPU bound threads. The plans can change. You are welcome to help.
> d> 
> d> idle_poll can significantly increase network response time. I'd suggest per-CPU (not per-interface) threads. This would keep user_frac code much simpler.
> 
> No, please don't spawn more idle_poll threads! :)

Not idle_poll but swi threads actually.
Btw, the loop discussed is just the same in ether_poll() and netisr_poll(). It could be splitted as a separate (inline?) function. Such complex macros aren't any good ;)

> As said, the idle_poll thread can't work on its own. idle_poll needs netisr_poll()
> to push it sometimes out of the priority pit. It is described in first mail of
> this thread.

idle_poll should surely remain a single entity.

> 
> d> Not sure about the coding help in the next weeks. My current project is on the pre-release stage and the kid is going to be born soon. I can join a bit later though.
> 
> There is no promises in the free project. Join when you can.