Re: Add dtrace support to pmcd

[fche@xxxxxxxxxx (Frank Ch. Eigler)]

nathans wrote:

> [...]  One final suggestion - it occurred to me while looking over
> pmcd_probe once more that the existing tracing had a split between
> pdu vs non-pdu trace traffic.  It would possibly be easy to maintain
> that in these probes, such that one can choose to (eg) not wear the
> pdu traffic trace cost, just the other lower-volume tracing.  [...]

I see what you mean.  The tracing-disabled costs for both options are
zero, so what's worth comparing are the tracing-activated ones.  In
the case in point, if one was not interested in PDU tracing, one'd
still pay a couple of microseconds per PDU to filter out the event.
If e.g. these PDU events occur orders of magnitude more frequently
than the others, it may well be worth it to separate them.

- FChE