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. 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 -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu@xxxxxxx
Attachment:
rt-2.6.33.7-latency-39516us.gz
Description: Binary data
Attachment:
rt-2.6.31.12-latency-33568us.gz
Description: Binary data
