Real Time kernel any experience?

Andy Green andy at openmoko.com
Wed Jul 2 15:27:03 CEST 2008


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Somebody in the thread at some point said:
| A quick and awesome response ;)
|
| I will keep in mind that, 1us is a really quick reaction time (like
| your replies  ;)) but the goal is for running a plc software  so I
| need to assure a regular latency time more than  the quickest time
| possible( but it helps to know than this react time is even
| possible).

OK FIQ doesn't help :-)  "Real time" means a few different things.

| kernel is able to connect with the high precision clocks of the arm
| processor?

I don't know about any really high precision clocks (I looked in vain
for a CPU cycle counter register) a while back, but Andrzej Zaborowski
has a patch in the andy branch that allows "dynamic tick" scheduling to
much higher resolution than normal

http://git.openmoko.org/?p=kernel.git;a=commitdiff;h=c27edf64d78abb0bb8d3004a231b6a2fb4c9931e

he's planning to use it to get low jitter mplayer action.  I guess this
won't do any harm for realtime.

- -Andy
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