Tor, Mike and all,
Here is something i'd like your opinion on...
Before programming the ETMv3/PTM, ETMCR:10 needs to be set to one and
when enabling the tracer, the bit needs to be cleared. Each time the
status of ETMSR:1 needs to be probed before moving on, something that
is quite costly. Is there a official limit of time for this operation
to be carried out?
The same question applies for ETB's FFCR:6 and FFSR:1.
At this time the driver wait for 100 usec before complaining - from
your experience, this this too short or it may need more time?
Thanks,
Mathieu
Al and Mike,
With the work on coresight/Perf integration proceeding as planned the
time to start looking at how configuration parameters can be conveyed
to the tracers using the perf cmd tool is fast approaching, and that's
where I need to pick your brain.
In your opinion and based on your experience with coresight, what are
the 5 most wanted configuration options we need to start with?
The question could also be thought of as the 5 most common thing
people configure when using coresight. Finding a way to give access
to all the configuration option of a tracer via cmd line won't be easy
but I believe it can be done. If we find a way to address the most
commonly used options as an starting point the rest should come
easily.
Please think about it and get back to me. My plan is to get the
discussion going with the perf maintainer about the best way to
proceed sometime this week or the next, depending on schedule.
Thanks,
Mathieu
Gentlemen,
As promised in the meeting the work on IntelPT done by Alex Shishkin
can be found on github [1]. All the user space integration work can
be found under tools/perf/. Adrian Hunter (formally at TI) did most
of the user space work. There is good documentation [2] that shows
how IntelPT is used and how the decoding library is called. On the
flip side the different between full trace and snapshot mode isn't all
that clear - I will touch base on that in my status update in SF. Get
back to me if you really can't wait that long and I'll be happy to
clarify.
I also bring your attention to two web pages. The first one [3] is an
awesome wiki on perf where most of the basics are highlighted. The
second one [4] is Brendan Gregg's in depth look at how he uses perf to
debug real life problems.
Regards,
Mathieu
[1]. https://github.com/virtuoso/linux-perf/tree/intel_pt
[2]. https://github.com/virtuoso/linux-perf/blob/intel_pt/tools/perf/Documentati…
[3]. https://perf.wiki.kernel.org/index.php/Tutorial
[4]. http://www.brendangregg.com/perf.html
Gentlemen,
Here is the log for this weeks team meeting.
Tor, is the timing for the meeting bad for you? You did not attend the
meeting while we all wanted to hear a few words of feedback from you for
the code Mike has published two weeks ago. Have you had a chance to look
at that?
--
Best Regards,
Serge Broslavsky <serge.broslavsky(a)linaro.org>
Core Development Project Manager, Linaro
M: +37129426328 IRC: ototo Skype: serge.broslavsky
http://linaro.org | Open source software for ARM SoCs
