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PMU(Performance Monitoring Unit) support on imx6

Question asked by Ramappa HUgar on Jun 6, 2017
Latest reply on Feb 5, 2018 by Saiyam Doshi

Hi,

 

Working on imx6-sabresd (cortex-a9) board and Kernel - 4.1.15. Trying to do performance evaluation by making use of performance monitoring unit(PMU).

Enabled the PMU in dts file and also enabled the performance related kernel configurations. 

 

I'm running "perf stat ls" command on the target. I'm getting following output.


Performance counter stats for 'ls':

10.287337         task-clock (msec)                   #             0.428 CPUs utilized
52                      context-switches                     #             0.005 M/sec
0                        cpu-migrations                         #             0.000 K/sec
47                      page-faults                               #             0.005 M/sec
7766306            cycles                                      #             0.755 GHz
0                       stalled-cycles-frontend             #             0.00% frontend cycles idle
0                       stalled-cycles-backend            #             0.00% backend cycles idle
0                       instructions                               #             0.00 insns per cycle
0                       branches                                  #              0.000 K/sec
0                       branch-misses                         #              0.00% of all branches

0.024054000 seconds time elapsed

 

Always Bold letter entries values are zero (instructions & branches).

1. whether cortex-a9 based imx6 soc supports PMU ?

2. If it supports PMU, why these entries are zero ?

If I want to debug, where to look into the kernel ?

 

Please provide your views on it.

 

Thanks,

Ram

 

 

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