[Beowulf] precise synchronization of system clocks

[Prentice Bisbal]

In the previous thread I instigated about running services in cluster
nodes, there was some mentioning of precisely synchronizing the system
clocks and this issue is also mentioned in this paper:

"The Case of Missing Supercomputer Performance: Achieving Optimal
Performance on the 8,192 processor ASCI Q" (Petrini, Kerbisin and Pakin)
http://hpc.pnl.gov/people/fabrizio/papers/sc03_noise.pdf

I've also read a few other papers on the topic, and it seems you need to
sync the system clocks to ~1 uS. On top of that, I imagine you also need
to synch the activities of each system so they all stop to do the same
system-level tasks at the same time.

The papers I read all mentioned different OSes, or at least specialized
hardware. Can this level of synchronization be achieved in Linux on
commodity hardware?  I imagine NTP doesn't have the resolution needed
for this, and Don Becker has some strong feelings against NTP.

I've tried googling on my own, but everything I come up with references
NTP, or just the papers I've already read.


-- 
Prentice