On Sun, 10 May 2009, dokapra wrote:
>>
>> Also, is there any other way to obtain a better time resolution, like in the
>> order of 1 microsec?
>>
>> Thank you
>>
> You can patch your 2.4-ts11 kernel with a linux-2.4-ts11-hrt.patch.gz
> from Files section. It improves gettimeofday resolution to the
> microsecond level, and fixes a bug (yes a BUG) with real time sliding
> away some 15 seconds a day because of wrong calculation.
That was a very old bug - I thought TS had fixed it years ago, after I
reported it (I have one of the early TS7200 boards).
> Patch works very
> well, and time keeping comes back to maximum slide of 5 sec/day which is
> what is possible with a given hardware.
Actually you can tune the system clock, using adjtimex (it can be built
into busybox) to get accuracy of about 1 sec in a few days, dependant of
course on your environment - no large temp changes etc. My board is set up
like that and keeps very accurate time over about a week. Of course if you
are connected to the internet and use ntp you can keep the clock even more
accurate.
> Make note that this is not the
> same as having kernel scheduler working at 1021Hz - your task scheduling
> still happens with 10ms resolution. Anyway this patch does not affect
> performance as a 1021 clock does and is safe to apply.
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HomePage: http://www.comp.leeds.ac.uk/jj
TS7200 Page: http://www.comp.leeds.ac.uk/jj/linux/arm-sbc.html
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