[time-nuts] sync computer clock ticks

[M. Warner Losh]

In message: <477E816D.5010803 at vogel.cx>
            Christian Vogel <vogelchr at vogel.cx> writes:
: For example, do you want to timestamp interrupts to synchronize 
: machinery? Or just note down the timestamps of bittorrent downloads very 
: precisely? Just synchronizing an otherwise idling computer is probably 
: much easier than a machine that is doing a lot of additional work that 
: can mess up the timekeeping by clogging the processor or just creating 
: varying stress on the power-supply lines.

That's the real question.  Like I said before, when you are down to
the microsecond level, what good is that?  The jitter from system
calls and such is going to be high enough to make that not completely
useful.  And if you are trying to do things to hardware with software
that requires that level of synchronization, you aren't going to get
it without timestamping done in hardware of some mutually observable
event (pps, packets on the network, etc).

Warner