Hi all
IMHO The problem is quite complicated because
+ common hardware is not designed for real time:
- sends multiple PDUs within one interrupt, and can be delayed
- Host adapter bus & infraestructure is not designed to garantee latency
etc...
+ software is also not designed for realtime
- drivers may timestamp in softirq's
- irqs has no deterministic latency either
etc...
So even if do_gettimeofday() has 1/CPUfreq resolution by using TSC register
packet timestamping meassurement is biased, how much?
anybody has studied this? are there reports/doc about this topic?
of course, this can be avoided by using specialiced hardware, but I'm not
interested on that and I would like to know how much I can trust this
timestamps
Any comment would be greatly appreciated
Thanks
Ulisses
Debian GNU/Linux: a dream come true
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