11.07 oprofile on panda busted?
dave.long at linaro.org
Thu Sep 15 17:48:05 UTC 2011
>Sorry, who is working on this and when is it going back in? perf is a
>significant feature and Panda is a very common board...
I have been unable to reproduce the boot hang problem after unreverting
the interrupt patch. Can those experiencing it please verify they are
using the latest released lmc tools to create their SD card? And can
you please send me your config file and Pandaboard revision?
It has been suggested that the limited sample count in the given example
is consistent with the fact the ARM oprofile code uses HZ as the
sampling frequency (even though it uses a separate timer). I'm not yet
familiar with the x86 code for setting the profiling interval on the fly
but Frederic Turgis's suggesting of doing the same thing on ARM makes a
whole lot of sense. We should make this a new requirement.
Once the interrupt issue is resolved I might suggest sampling cpu-cycles
as a workaround to real-time sampling granularity, except that there
apparently is an issue with reliably getting interrupts from the PMU.
Does anyone know if this is still a problem in the A9 (I've only seen it
discussed regarding the A8)? If it's still an issue I think it simply
kills using PMU event counters with oprofile.
We need to do a little work to make configuring hardware events counters
into the kernel easier. A recent change means that you need to set at
least a couple independent config options for this. This should be
simple to fix.
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