linux perf analysis

$ gcc -Wall -O2 -g3 -o sum sum.c
$ sudo perf stat ./sum 5000

 Performance counter stats for './sum 5000':

      10778.084202      task-clock (msec)         #    0.999 CPUs utilized
               388      context-switches          #    0.036 K/sec
                 0      cpu-migrations            #    0.000 K/sec
                53      page-faults               #    0.005 K/sec
    46,340,712,834      cycles                    #    4.300 GHz
    32,565,164,787      instructions              #    0.70  insn per cycle
    10,014,271,202      branches                  #  929.133 M/sec
     1,614,607,275      branch-misses             #   16.12% of all branches

      10.783577509 seconds time elapsed

$ gcc -Wall -O3 -g3 -o sum sum.c
$ sudo perf stat ./sum 5000

 Performance counter stats for './sum 5000':

       1169.886277      task-clock (msec)         #    0.999 CPUs utilized
                43      context-switches          #    0.037 K/sec
                 0      cpu-migrations            #    0.000 K/sec
                55      page-faults               #    0.047 K/sec
     5,029,957,464      cycles                    #    4.300 GHz
    18,779,056,473      instructions              #    3.73  insn per cycle
     1,257,536,422      branches                  # 1074.922 M/sec
         1,018,874      branch-misses             #    0.08% of all branches

       1.170696400 seconds time elapsed