On Thu, Oct 07, 2010 at 04:44:58PM +0200, Detlev Zundel wrote:
>Hi,
>
>during tests with the rt-preempt kernel on PowerPC, I stumbled across
>this really weird phenomenon of cyclictest latencies > 30ms. The test
>system is a TQM5200 supported mainline, so the complete kernel source is
>unmodified mainline + rt-patch. The -00001 in the kernel revision is
>due to the fact that I commited the results of applying the respective
>rt-patch to my local git repo.
>
>To debug the problem, I turned the latency tracers on and started
>cyclictest with 'cyclictest -n -p80'. This looks quite good, hackbench
>and the cache calibrator do not do much harm, _until_ I start to do a
>ping flood from outside. Then within a few seconds the high latencies
>occur. To test for a regression, I did the same test under
>2.6.33.7-rt29 and 2.6.31.12-rt21. Both versions yield similar results.
did you try mpc5121ads board with cyclictest test?
I wonder whether it's about powerpc arch common issue or 5200 special
issue.
Thanks
walimis
>
>Attached are the trace outputs for those events (gziped as they are
>larger than 300KiB).
>
>It looks like the scheduling goes completely wrong as there is even the
>idle task running before the runnable cyclictest gets scheduled in. Can
>someone give me a hint on what may be wrong here?
>
>Thanks
> Detlev
>
>--
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>HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
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