stable/7 bce(4) out of buffers

[David Christensen]

> > > dev.bce.0.com_no_buffers: 130228
> >
> > Hmm, in HEAD there looks to be a hw.bce.rx_pages that can be set to
> > 1, 2, 4, or 8.  It defaults to 2.  In the 7 driver it looks like this
> > is a #define in sys/dev/bce/if_bcereg.h (RX_PAGES on line 6710).  Try
> > changing RX_PAGES from 2 to 4 (or 8) and recompiling your kernel (or
> > bce driver) and see if that helps.
> >
> 
> Indeed, I was eyeballing that just now.  I'll post back with results.
> 

Adding buffers might help but more often than not you really should
adjust the interrupt coalescing sysctls (hw.bce.rx_quick_cons_trip, 
hw.bce.rx_ticks) so the hardware releases frames to the OS more
frequently and fetches new buffers.  Setting both values closer to 1
improves latency and small packet performance but does increase CPU
load due to the increased number of interrupts.

Dave