[lttng-dev] Lttng add-context perf commands gives me error

[Mathieu Desnoyers]

----- On Nov 17, 2015, at 4:46 PM, Hani Nemati <hani_nemati at yahoo.com> wrote: 

> Hi,
> I am trying to count last level cache misses by using lttng add-context command.
> I use add-context to add perf:cpu:LLC-load-misses to my channel but I see an
> error. There is no error for other perf events. Just two perf events including
> perf:cpu:LLC-load-misses and perf:cpu:LLC-store-misses give me the following
> error:
> Error: perf:cpu:LLC-load-misses: Add kernel context failed
> Warning: Some command(s) went wrong

> Here is result of "uname -a" on my computer:
> Linux nemati 3.16.0-51-generic #69~14.04.1-Ubuntu SMP Wed Oct 7 15:32:41 UTC
> 2015 x86_64 x86_64 x86_64 GNU/Linux

> Here is the command that I used:
> #lttng enable-channel -k test
> #Kernel channel test enabled for session hh
> #lttng add-context -k -t perf:cpu:LLC-load-misses -c test
> Error: perf:cpu:LLC-load-misses: Add kernel context failed
> Warning: Some command(s) went wrong

> I also tried it on other machines.

It is possible that your architecture does not expose this counter to perf. 
Did you try using this PMC with the perf tool ? 

Thanks, 

Mathieu 

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-- 
Mathieu Desnoyers 
EfficiOS Inc. 
http://www.efficios.com 
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