[time-nuts] sync computer clock ticks

[Christian Vogel]

I forgot two things!

(1) It's all Linux, with stock kernel.org kernels, see below.
(2) see comment about the application below.

Christian Vogel schrieb:
> at work, I use it to sync all servers and workstations to 4 stratum 1 
> NTP-servers. I get ~100us offset usually. Without special hardware I'd 
> say that 1usec is not possible.
> 
> Server, Gig-Ethernet, 4 hops (>=Gigabit) to ntp:
> *ntp2-rz.rrze.un .GPS. 1 u  758 1024 377 1.225 **-0.179** 0.068
> (HP DL380-G3, Dual 3.2 GHz P4, no powersaving)
> -> Temperature fluctuates +/- 3 Deg-Celsius every 20sec due to HVAC
Kernel 2.6.21.3 SMP

> 
> Client, 100Mbit, 5 hops (last 4 are better than Gigabit):
> *ntp2-rz.rrze.un .GPS. 1 u  987 1024 377 1.577 **-0.111** 0.091
> (P4-Celeron, 2.4 GHz, currently throttled to 300 MHz)
> -> Temperature currently stable and possibly very cool, have not
>  been in my office for a week :-)
Kernel 2.6.22.1 PREEMP

And: We should not forget the original poster's question about if 1 usec 
precision can be achieved? I'd say that the most important thing about 
this question is, what application the precision is needed for.

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.

Scatterbrained,
	Chris