[Xen-users] Reading hardware performance events in xen dom0

[Tsafack Chetsa Ghislain Landry <ghislain.landry.tsafack.chetsa@xxxxxxxxxxx>]

Greetings,

Sorry for disturbing, I have just installed Xen on my system (kernel version 2.6.32-5-xen-amd64) and I would like to read hardware events in dom0, I have a program which usually do that in non-Xen kernels (see beneath).

void open_perf(struct perf_event_attr* attr) {

  static int current=0;

  int cpu;

  for(cpu=0; cpu<NBCORE; cpu++) {

    perfctr[current+cpu]=sys_perf_event_open(attr, -1, cpu, -1, 0);

    if(perfctr[current+cpu] <0) {

      printf("open : %d (%d et %d)\n", perfctr[current+cpu], attr->config, current+cpu);

      exit(1);

    }

  }

  current+=NBCORE;

} 

The problem is that the system call "sys_perf_event_open" systematically returns -1

I was wondering whether anyone has experienced the same issue and how I get rid of that.   

I tried using perf, but I guess the same thing happens:

here is an example:

Performance counter stats for 'mpirun -np 2 ./ep.A':

   55075.066063  task-clock-msecs         #      1.986 CPUs

            282  context-switches         #      0.000 M/sec

              4  CPU-migrations           #      0.000 M/sec

           2330  page-faults              #      0.000 M/sec

  <not counted>  cycles

  <not counted>  instructions

  <not counted>  cache-references

  <not counted>  cache-misses

   27.735049988  seconds time elapsed

--

Landry

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