linaro-release team mailing list archive

[Fathi Boudra <fathi.boudra@xxxxxxxxxx>]

>From Dave L. (http://lists.linaro.org/pipermail/linaro-
dev/2011-September/007560.html) :

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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https://bugs.launchpad.net/bugs/843628

Title:
  perf failure on panda (omap4)

Status in Linaro Ubuntu Evaluation Builds:
  Confirmed
Status in “linux-linaro-omap” package in Ubuntu:
  Confirmed

Bug description:
  Though perf lists the PMU events but fails to gather performance
  counter statistics on panda

  # perf list

  List of pre-defined events (to be used in -e):

    cpu-cycles OR cycles                       [Hardware event]
    instructions                               [Hardware event]
    cache-references                           [Hardware event]
    cache-misses                               [Hardware event]
    branch-instructions OR branches            [Hardware event]
    branch-misses                              [Hardware event]
    bus-cycles                                 [Hardware event]

    cpu-clock                                  [Software event]
    task-clock                                 [Software event]
    page-faults OR faults                      [Software event]
  [...]

  # perf stat sleep 1
    Error: cache-misses event is not supported. 
    Fatal: Not all events could be opened.

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