On 21/08/2014 11:51 pm, Gedare Bloom wrote:
On Thu, Aug 21, 2014 at 3:03 AM, Sebastian Huber
<sebastian.hu...@embedded-brains.de> wrote:
On 20/08/14 16:05, Joel Sherrill wrote:
The clock handling is entirely broken on SMP and not scalable. Our clock
infrastructure is only good enough for uni-processor systems, but even here
the usage of nanosecond timestamps is suboptimal. I would rather use
something like the FreeBSD time hands:
http://phk.freebsd.dk/pubs/timecounter.pdf
Nice. It looks like it would take:
1) Convert the 64-bit timestamps into bintime: a split time_t
'seconds' + uint64_t 'frac' format. The math is shown in the paper.
2) A lock-free ring buffer for the timehands.
3) The timecounter structure that describes the hw clock source, and a
way to register timecounters from BSPs.
4) Rewrite tick handling to do the refresh operation.
Did I miss anything?
If we implement this it would be nice to get NTP working cleanly with
RTEMS. The RSB is now building NTP.
Chris
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