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

[Hani Nemati]

Hi Mathieu, 
LCC is last level cache and it is shared between CPU cores. Also, I was running several VMs in background. That's why I used sleep command. Based on Intel's manual r0109 is raw identifier for LCC-load-misses, 
The question is how can I fix the problem since Lttng is using perf symbolic name. 

Thanks, 
Hani  

     On Wednesday, November 18, 2015 3:19 PM, Hani Nemati <hani_nemati at yahoo.com> wrote:
 

 There is no PERF symbolic name for LLC-load-misses but I can use raw identifier to find out Number of code read, data read that miss the LLC. Here is the command that I used.
 
#perf stat -e r0109 sleep 2
 Performance counter stats for 'sleep 2':

               117      r0109  

Do you have any idea why I don't have the symbolic name? Is there any way to give raw identifier instead of perf:cpu:LLC-load-misses? 







     On Wednesday, November 18, 2015 9:45 AM, Mathieu Desnoyers <mathieu.desnoyers at efficios.com> wrote:
   

 

----- 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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