Subject: Re: Interface traffic timestamps
To: Martin Husemann <martin@duskware.de>
From: Jonathan Stone <jonathan@dsg.stanford.edu>
List: tech-kern
Date: 06/11/2004 10:46:21
In message <20040611065026.GB26170@drowsy.duskware.de>,
Martin Husemann writes:

>Any big objections? I'll post patches here otherwise.


I'd say: please don't even try to do this on gigabit or 10GbE links;
the performance hit simply isn't worth it.  (My back-of-the-finger
estimate leaves me suspecting mono-time is too coarse to be useful.

Or turn it around: bumping a microsecond mono_time once per input
frame, when frames are only 50 ns long, is going to completely stuff
up your time-keeping.

Please consider that a very loud objection. :-/.  To me, that suggests
a per-interface flag, to control whether to do the mono_time
timestamps, or not.

Alternatively: is the seconds portion of (mono_)time good enough for
your purposes? Do you really care about microseconds or milliseconds,
for whether to drop a connect-time-charged ISDN line?