* Harald Gustafsson ([email protected]) wrote: > 2011/4/6 Mathieu Desnoyers <[email protected]>: > > Hrm, I should probably do this, can you try this patch out ? Can you > > test it and report if it fixes your problem ? > > Thanks it fixes the problem. I made the corresponding changes in my > architecture's trace-clock.h which is a copy & paste of the omap > version. So I assume this would also work for the OMAP. > > Now I only have the clock mismatch between the cores to deal with, > lttv complains for threads that are inserted before they are forked > (range is 10 us - 10 ms mismatch depending on run). I think it is due > to that the cores enters/leaves WFI unsynced and hence runs on cycle > counter and 32kHz clock in a different pattern and I get some error > due to this. So far I run cpufreq on performance to not introduce > even more uncertainty. Have you tried the code on a OMAP4?
I haven't tested this on OMAP4 personally, so I'm really interested in your feedback. I did my development on OMAP3 UP, but I designed the trace clock to support SMP (but it's not tested by myself, others have reported success though). You might want to try with and without: - power management suspend/resume - cpufreq changes There is code in trace clock to support each of these. 10 ms offset between the cores is way too much, so I guess there is something wrong there. First identifying if it's suspend/resume or cpufreq that are causing the problems would help us there. What do you mean by "enters/leaves WFI" ? (WFI TLA means ?) Given what you say above, cpufreq running in performance mode should make it OK as far as cpufreq is concerned, although there might be some discrepancy at boot time if the cpufreq mode is only changed later. I suspect that the problem might come from that your OMAP4 architecture does not call the trace clock resync after power management resume, like OMAP3 is doing. You might also want to have a look at the Linaro 2.6.38 git tree, which integrates LTTng with Linaro, which might have better support for OMAP4 suspend/resume. I'm really interested in fixing this up, but I'll need your help for testing. Thanks! Mathieu > > Regards, > Harald > -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com _______________________________________________ ltt-dev mailing list [email protected] http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
