DEVICE_POLLING with SMP

[Kevin Day]

Has anyone made any headway with getting polling(4) to work with a SMP 
kernel?  Last May this was discussed on here briefly with me, Luigi and 
Don Bowman, which seemed to indicate that the majority of what needed 
to be fixed to make this work would be some kind of locking in 
idle_loop to make sure only one CPU gets into the polling code at once.

I've got a case where enabling SMP gives me a 20-30% performance boost, 
or if I turn polling on I get another 10-15% boost. I'd love to see 
what the two together could do.