Gilles Chanteperdrix wrote: > On Jan 28, 2008 2:34 PM, Jan Kiszka <[EMAIL PROTECTED]> wrote: >> Gilles Chanteperdrix wrote: >>> ... >>> The behaviour you get may be due, for instance, to the fact that the >>> processor goes into some sleep mode when idle and to a wake-up >>> latency; if you run some load, there is no wake-up latency. It is hard >>> to say anything. In order to investigate, I would instrument the >>> kernel to trace the irq masking sections. >> Don't we have the I-pipe tracer on this platform? > > Unfortunately, the tracer on arm has too much overhead to give > meaningful results.
Hmm. Unless the system becomes unusable while running the tracer, I don't see the show-stopper yet. We are looking for an increase of the latency when triggering a certain event. That should remain measurable even if the base latency is far higher than usually. Do you know what makes the tracer so slow? My "lowest-end" experience with it are based on a 133 MHz Pentium where the tracer doubled the worst-case latencies, but the results remained useful for spotting long paths. Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
