[time-nuts] Serial port server .. any interest in a write up on using ?

[Attila Kinali]

On Tue, 22 May 2012 17:28:47 -0700
Hal Murray <hmurray at megapathdsl.net> wrote:

> Note that 4 samples are way off scale.  The target machine is idle, but the 
> packets are going over a wifi link that has other traffic but is far from 
> overloaded.  Yes, this is wifi rather than a simple ethernet switch.
> 
> I suspect I could make similar problems with a pair of ethernet switches.

On an ethernet it looks quite different:

64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=164 ttl=64 time=0.189 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=165 ttl=64 time=0.182 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=166 ttl=64 time=0.189 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=167 ttl=64 time=0.188 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=168 ttl=64 time=0.196 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=169 ttl=64 time=0.182 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=170 ttl=64 time=0.191 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=171 ttl=64 time=0.194 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=172 ttl=64 time=0.185 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=173 ttl=64 time=0.172 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=174 ttl=64 time=0.177 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=175 ttl=64 time=0.186 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=176 ttl=64 time=0.186 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=177 ttl=64 time=0.190 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=178 ttl=64 time=0.189 ms
64 bytes from kaos.kinali.ch (82.197.186.49): icmp_req=179 ttl=64 time=0.203 ms

Network is a destkop - switch1 - switch2 - ntp box.

The switches are two Level1 Gbit smart switches.
The desktop is a ~4y old Xeon 2GHz system with a Gbit interface
The ntp box is a AMD Geode LX 500MHz system with a 100MBit interface
Both running linux.

There aren't noticable more jitter for moderate (1-2 MByte/s) traffic.
(Probably visible if i would do a statistical analysis...but..)


			Attila Kinali
-- 
Why does it take years to find the answers to
the questions one should have asked long ago?