Count events

perf stat is used to count interested events: 

  1. # perf stat
  2. ^C
  3.  Performance counter stats for 'system wide':
  5.            2376.91 msec cpu-clock                 #    2.000 CPUs utilized
  6.                123      context-switches          #    0.052 K/sec
  7.                  1      cpu-migrations            #    0.000 K/sec
  8.                  0      page-faults               #    0.000 K/sec
  9.          102707402      cycles                    #    0.043 GHz                      (50.10%)
  10.           34857921      instructions              #    0.34  insn per cycle           (75.00%)
  11.            7832558      branches                  #    3.295 M/sec                    (75.02%)
  12.             168058      branch-misses             #    2.15% of all branches          (74.88%)
  14.        1.188558385 seconds time elapsed

The above example shows some default events which “perf stat“ will count. -I option can be used to set the frequency (unit is ms) of displaying result, and --interval-count is to specify how many times you want to run “perf stat“. Check following example: 

  1. # perf stat -I 1000 --interval-count 5 -e cycles
  2. #           time             counts unit events
  3.      1.000454837            5005909      cycles
  4.      2.001134074            3579497      cycles
  5.      3.001690949            4350491      cycles
  6.      4.002221214            3504926      cycles
  7.      5.002936768            4941014      cycles