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Re: Issues with @perf directives in systemtap 3.1 on Ubuntu 16.04LTS


On 01/23/2017 07:50 AM, Geoffrey Blake wrote:
> Hi all,
> 
> I have been trying to make use of the perf.stp example modified for my
> own program I am trying to profile.  I set the perf.hw probes to be
> system wide by not supplying a process, but when my other probes
> trigger and I read the counters with the @perf() directive, the number
> returned for the counters is always the same junk number (it varies
> between runs, but never changes during a run).
> 
> I am not sure what could be going on.  I have tried the systemtap
> package that ships with Ubuntu 16.04LTS and compiled from the tip of
> the git repository.  Both versions have the same failure.  Any help
> would be appreciated on how to debug this further.

Does the unmodified perf.stp example work on your system? How are you
running your modified example?

-- 
David Smith
dsmith@redhat.com
Red Hat
http://www.redhat.com
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256.837.0057 (fax)


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