[Beowulf] precise synchronization of system clocks

[Lombard, David N]

On Tue, Sep 30, 2008 at 12:01:57PM -0700, Donald Becker wrote:
> On Tue, 30 Sep 2008, Lawrence Stewart wrote:
> 
> > On Sep 30, 2008, at 12:07 PM, Lux, James P wrote:
> > > On 9/30/08 8:37 AM, "Robert G. Brown" <rgb at phy.duke.edu> wrote:
> > > The grottiest grungy GPS receiver can probably do 100ns on its 1pps
> > > tick,
> > > and most are in the 20ns range.  There ARE receivers that have
> > > systematic
> > > errors (i.e. Some sort of sawtooth in the error) and, of course,
> > > there are
> > > countless schemes to compensate in one way or another.
> > So someone with some grad students and soldering irons should hook up
> > the 1 pps
> > output of a GPS to, say, the carrier detect pin on the unused RS232
> > ports of all their
> > nodes, and write some software...
> 
...
> 
> Meanwhile, I'll try to find out where I can plug a serial cable into a
> modern server...

Ah, come on ;)

A serial-USB dongle will do just fine, as will a USB-based GPS receiver...

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