Subject: Re: microtime
To: Sean Doran <smd@ab.use.net>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: tech-kern
Date: 08/22/2002 13:50:23
[[ Sean Doran says much...]
All of this is very hard to object with.
However, dont forget that:
* NTP is very carefully crafted so that what matters ot it
is not aboslute delay, but *variance* in delay (aka jitter).
Dave Mills has this down to where he can pull the minimum
rtt out of the filters on his local-campus machines
and give very good estimates of the raw,
guaranteed-not-to-exceed forwarding latency of local switches.
* In internets (small i, aka intranets) the end-systems often are the
bottleneck. I dunno about you, but i have more gigabit-connected
machines than I can keep track of, and I'm waiting for prices on
10-gig blades to start falling.
* the coarseness of NetBSD (and lack of Mill's "nanokernel") is
already a drawback of NetBSD. Even I am looking serious at FreeBSD
for my GPS radio. This thread has also kicked off some discussion
of PHK's timecounter abstraction (the idea, not necessarily the extant
code or kernel API).