igb(4) Pondering a bind to cpu patch

[Sean Bruno]

On Wed, 2012-04-25 at 06:32 -0700, John Baldwin wrote:
> CPU IDs are not guaranteed to be dense.  However, you can use
> CPU_FIRST() and 
> CPU_NEXT() with your static global instead.
> 
Ah, does CPU_NEXT() reset to 0 when it reaches the end of its list of
CPUs?


> OTOH, if igb were to just leave the interrupts alone instead of
> binding them 
> by hand, they would get round-robin assigned among available cores
> already.  I 
> think in this case the best approach might be to add a tunable to
> disable 
> igb's manual binding and instead let the default system round-robin
> be 
> preserved. 

also, yes.  Why *are* we binding to CPUs in the first place?  Are we
afraid that the scheduler won't do the right thing and we're trying to
work around some unknown performance issue ?

Sean