[comp.protocols.time.ntp] Unix clock resolution revisited

rbthomas@JOVE.RUTGERS.EDU (10/31/90)

>
>                                            Think we should apply for
> a grant of some Cray time to run clockres on it?  I'm not that curious.
> 
> Marion
> 

I was (curious, that is), so I ran it on the Y/MP at PSC.  This is
what I got.

Script started on Tue Oct 30 23:19:03 1990
pscymp$ for i in 1 2 3 4 5 6 7 8 9 0
> do
> clockres
> done
Clock step resolution 29 microseconds or better
Clock step resolution 30 microseconds or better
Clock step resolution 32 microseconds or better
Clock step resolution 29 microseconds or better
Clock step resolution 32 microseconds or better
Clock step resolution 33 microseconds or better
Clock step resolution 30 microseconds or better
Clock step resolution 30 microseconds or better
Clock step resolution 30 microseconds or better
Clock step resolution 30 microseconds or better
pscymp$ <EOF>
<EOF>
Script done on Tue Oct 30 23:19:23 1990

For comparison purposes, I ran it on a Convex C1/XP we have locally,
and got this.  Does this mean that the Y/MP is only 30 percent faster
than the C1/XP ? (;->)

Script started on Tue Oct 30 23:27:32 1990
kingtut$ for i in 1 2 3 4 5 6 7 8 9 0
> do
> clockres
> done
Clock step resolution 36 microseconds or better
Clock step resolution 38 microseconds or better
Clock step resolution 39 microseconds or better
Clock step resolution 36 microseconds or better
Clock step resolution 36 microseconds or better
Clock step resolution 36 microseconds or better
Clock step resolution 38 microseconds or better
Clock step resolution 38 microseconds or better
Clock step resolution 36 microseconds or better
Clock step resolution 38 microseconds or better
kingtut$ ^D

script done on Tue Oct 30 23:28:08 1990

========================================================================
Rick Thomas, Manager
Supercomputer Remote Access Center, Rm D117
Rutgers University, College of Engineering
Brett and Bowser Roads
Piscataway, NJ 08855-0909

Phone: (201) 932-4301
Internet: rbthomas@jove.rutgers.edu
UUCP: {any backbone site}!rutgers!rbthomas
Alternate UUCP: {convex|c1apple|karna}!kingtut!rbthomas

"Soap and education are not as sudden as a massacre,
	but they are more deadly in the long run."  -- Mark Twain
========================================================================

Mills@udel.edu (10/31/90)

Rick,

I have reports that the Cray can keep time to the basic CPU cycle,
something less than 10 ns. If that really is the case, NTP can
locate your CPU within the machine room to less than ten feet.

Dave