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How to use perf_event_open() function exposed by linux kernel to obtain RDT llc occupancy, local bandwidth and total bandwidth

Hi, 

I am trying to read RDT counters, which are llc_occupancy,llc_local_bytes,total_bytes.

These counters are available via perf list, as intel_cqm/llc_occupancy , intel_cqm/llc_local_bytes/,intel_cqm_total_bytes/

I was able to read data via these counters using perf stat.

How can I read these counter values for a specific process "P", using perf_event_open.

I did the following, and it didn't help much

                  perf stat -e intel_cqm/llc_occupancy/ -a -p 5816 -vv

and used the same perf_event_attr parameters in the perf_event_open, and the api didn't get the counters.

Also, I noticed that, when I execute the above command, it returns with 
                      sys_perf_event_open: pid 5816  cpu -1  group_fd -1  flags 0x8
                      sys_perf_event_open failed, error -22

which is an invalid argument, however at the end of the command, it displays the llc occupancy.

Is it possible to read the RDT counters for a specific process id?

Thanks,

Udaya Puvvadi

 

 

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