[Beowulf] IEEE 1588 (PTP) - a better cluster clock?
patrick at myri.com
Fri Jul 20 13:07:09 PDT 2007
Patrick Ohly wrote:
> That's all for now (and probably enough stuff, too ... although perhaps
> you prefer detailed emails over bullet items on a PowerPoint
> presentation). So what do you think?
Since you are asking, here is my personal opinion: I don't think there
is a need for a system-wide PTP service. NTP's precision is good enough
for comparing log and other administration needs. The only requirement
for a high precision/high accuracy global clock reference that I would
consider legitimate is for tracing tools (that's where you come from).
In this case, why not running NTP as part of the tracing environment ?
You could say that it would be useful to factorize this functionality so
that it can be shared by several tracing libraries. I don't think it's
worth the effort, as one rarely uses two different tracing tool at the
I don't know enough about PTP to comment on the implementation, except
that relying on multicast is a bad, bad idea. It does not scale and it's
very unreliable under load (induces contention if reliable).
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