On Fri, May 23, 2003 at 12:51:13AM +0900, YAMAMOTO Takashi wrote:
> > Modified Files:
> > 	src/sys/dev/ic: wi.c
> > Track TX exceptions. This will eventually enable round-robin retries
> > (for fairness) and RTM_LOSING or some such other message to indicate
> > a losing wireless destination.
> > 
> > From FreeBSD.
> 
> why doesn't WI_INTR include WI_EV_TX_EXC?

Right now, wi only uses WI_EV_TX_EXC to update the statistics counters.
I think that if WI_INTRS contained WI_EV_TX_EXC, it would add to
the interrupt overhead without gaining us a lot in the "timeliness"
of statistics.

In a brief analysis, it did not look like the statistics can fall
further behind than the maximum number of simultaneous outstanding
transmissions, WI_NTXBUF (3), because we are guaranteed to see at least
as many WI_EV_ALLOC (which generates an interrupt) as WI_EV_TX_EXC.

We will also occasionally "forget" as many as WI_NTXBUF Tx errors on
interface up/down and also on change of media. I think that we would
stand to miss a few even if WI_EV_TX_EXC was in WI_INTRS, however.

Let me know if my explanation is not satisfactory.

Dave

-- 
David Young             OJC Technologies
dyoung@ojctech.com      Urbana, IL * (217) 278-3933