[cadynce] end to end measurements in cadynce experiments and NTP clock sync

[gthaker at atl.lmco.com]

Adam,

As you start to set up to run GT-4 and start to measure the end to end
time, to what extent are you worried about clocks of the starting and
ending nodes of the application strings being sufficiently synchronized so
as to get decent end to end time measurements? With NTP the test Blades,
assuming all are connected via gigabit net to a local NPT time server,
should stay within 1msec to 5msec of each other. However, ATL's Jonathan
Walsh, who has been attempting to test the "Case 32" 150 SCI setup and to
take end to end measurements finds that at least at Emulab (Utah's) when
the nodes comeup they are quite far and after an "ntpdate" they still
don't really get well sync'ed up. (We are going to gather some measurement
data to get better handle on what we are seeing). ANyway, I thought I
would ask if this is an issue in the Maryland testbed or not.

Gautam