[Beowulf] IEEE 1588 (PTP) - a better cluster clock?
James.P.Lux at jpl.nasa.gov
Tue Jul 24 16:40:06 PDT 2007
At 01:11 PM 7/24/2007, Patrick Geoffray wrote:
>Jim Lux wrote:
>>Highly parallelized real time signal processing? Seems like a classic
>Wouldn't you need a real-time OS and a real-time communication layer
>to do real-time processing? Or at least within the same level of
>time accuracy ?
>The Linux scheduler is still on a 10ms quantum of time, and QoS in
>network is still about what to drop first, not guaranteeing resources.
Consider something where you had something like a frame grabber. you
might need microsecond precision for some aspects, but just
guarantees of sufficient resources for farther back in the chain.
>If PTP is as good (accuracy, resource usage) as the specialized
>methods, then using a common implementation is the best deal.
>However, application-specific/architecture-specific synchronization
>may be more efficient. The trade-off is between the performance of
>the first versus the cost of the second. That's the rule behind
James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
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