Hi Wolfgang, On Wed, Jun 18, 2008 at 10:07:05AM +0200, Wolfgang Grandegger wrote: > Hello, > > I currently re-doing latency measurement with my TQM5200 board under > Linux 2.6.25. With 2.6.24-rt1 "cyclictest -n -p80 -i1000 -t1" reported a > maximum latency of 170us. With 2.6.25.4-rt5 I'm unable to reproduce such > reasonable latencies. cyclictest shows quickly latencies up to 600 us. > What has changed in the meantime? Any ideas how to get better latencies? > I've just brought up my mpc5200b board with 2.6.25.4-rt6 and ran for serveral times cyclictest on it. I ran my tests with the same parameter as you mentioned. As non-rt workload I ran an endless loop of "ls /". Based on the issue with rcu, about which we discussed some times ago I also tried some combinations of randomly chosen debugging options. So far I was not able to reproduce your problem. Same for 2.6.25.4-rt5. Could you possibly send me your kernel configuration, so I might probably have a try here on my board? Cheers -- Dipl.-Ing. Luotao Fu | Phone: +49-5121-206917-3 Pengutronix - Linux Solutions for Science and Industry Entwicklungszentrum Nord http://www.pengutronix.de
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