On 02.09.2015 15:43, David Ahern wrote:
On 9/2/15 3:28 AM, Dennis Gnad wrote:
Hi,
I am interested in timestamped performance counter data (with a
specified sampling rate) as there is supposed to be saved in perf.data
when I use "perf record -T".
However, I don't understand the complete output of "perf report -D", and
can't figure out which parts of it are the timestamps. Is there any
documentation that I overlooked?
Actually if it helps, I am only interested in the name/raw event, value,
and timestamp, without any code/library information. Maybe the
information on which CPU it is from (on a multicore) could be
interesting as well.
Do I need to start looking into the code? Any good place to start? I
probably need to do this anyway, instead of parsing the really large
perf report -D output.
Use 'perf script' instead of 'perf report -D' to dump the samples.
OK, I really overlooked this. Thank you!
But now I am confused by that output. If I run for example:
$ perf record -F 100 -T -e cycles,cache-misses ./my_code
my understanding is, that at 100Hz, the values of the specified
performance counters are read. But when I run:
$ perf script -f time,event
2001301.016880: cycles:
2001301.016883: cycles:
2001301.016885: cycles:
2001301.016886: cache-misses:
2001301.016887: cache-misses:
2001301.016889: cache-misses:
2001301.016890: cycles:
2001301.016925: cache-misses:
2001301.017000: cycles:
2001301.031339: cycles:
[..]
I don't get the values of the events, only that they "happened", which
isn't that helpful if it is only sampled at a certain frequency. I also
tried other options, but don't seem to be able to get the actually
sampled values of the counters.
Any idea what am I missing? Much thanks in advance!
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