Re: RFC: NAPI packet weighting patch

[Andi Kleen <ak@xxxxxxx>]

> This is very hw-dependent, since there are NICs that read descriptors in
> batches anyways - but the second argument below is compelling.

The computing time must be quite long to be really a win.
You need to waste a few hundred cycles at least on a modern fast CPU.

-Andi
> > 
> > 2) As shown above, it gives you compute time which can be used to
> >    schedule the prefetch.  This nearly makes RX replenishment free.
> >    Instead of having the CPU spin on a cache miss when we run
> >    eth_type_trans() during those cycles, we do useful work.