[Beowulf] precise synchronization of system clocks

[Lombard, David N]

On Mon, Sep 29, 2008 at 01:10:49PM -0700, Prentice Bisbal wrote:
> 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 IEEE-1588 "Precision Time Protocol" can provide such levels of global clock
synchronization.  

Shameless plug: See "Hardware Assisted Precision Time Protocol (PTP, IEEE-1588)
- Design and Case Study" presented at the recent LCI conference;
<http://www.linuxclustersinstitute.org/conferences/archive/2008/technicalpapers.html>

-- 

David N. Lombard, Intel, Irvine, CA
I do not speak for Intel Corporation; all comments are strictly my own.