Re: Does oprofile suffer from aliasing?

On 2015-04-30, William Cohen <[email protected]> wrote:
>
>> AFAICT the ARM926 core doesn't have a PMU at all -- I can find no
>> mention of one in either ARM docs for the ARM926 or Atmel docs for the
>> at91 parts.
[...]
>> Is there such a thing as software-only PMU support?

> The perf command included with newer kernels (since 2.6.31) allow
> recording both performance monitoring hardware events and software
> events.

So that would be a sort of software-only PMU support (from the user's
POV)?

> Assuming that perf is working you should be able to do following to
> see what events it supports:
>
> # perf list
[...]
> # perf record --freq 1000 -e cpu-clock -a sleep 10
[...]
> # perf report

OK, thanks.  It's probably time to try to get a newer kernel running. 
IIRC, Atmel provides kernel config examples for a few different
versions up to 3.6 for my platform.

So, let's say I have a hardware interrupt I can hook stuff to (I do),
and I can generate "random enough" edges on the pin in question with a
predictable frequency distribution (that might take a bit of
soldering, but shouldn't be too difficult).

Can I stick something in the ISR for that interrupt that will cause a
"sample"?

-- 
Grant Edwards               grant.b.edwards        Yow! These PRESERVES should
                                  at               be FORCE-FED to PENTAGON
                              gmail.com            OFFICIALS!!


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