It is cumbersome to manually calculate the total time spent in a given
syscall by multiplying the average value with the number of calls.

Instead, we now do this directly inside perf trace.

Note that this is also done by 'strace', which even adds a column with
relative numbers - something we could do in the future.

Example:

  perf trace -s find /some/folder > /dev/null

   Summary of events:

   find (19976), 700123 events, 100.0%, 0.000 msec

     syscall            calls    total       min       avg       max      stddev
                                 (msec)    (msec)    (msec)    (msec)        (%)
     --------------- -------- --------- --------- --------- ---------     ------
     read                   4     0.006     0.001     0.002     0.003     27.42%
     write               8046     9.617     0.001     0.001     0.035      0.56%
     open               34196    40.384     0.001     0.001     0.071      0.30%
     close              68375    57.104     0.001     0.001     0.076      0.25%
     stat                   4     0.004     0.001     0.001     0.001      3.14%
     fstat              34189    27.518     0.001     0.001     0.060      0.34%
     mmap                  13     0.029     0.001     0.002     0.003     10.74%
     mprotect               6     0.018     0.002     0.003     0.005     17.04%
     munmap                 3     0.014     0.003     0.005     0.006     24.87%
     brk                   87     0.490     0.001     0.006     0.016      6.50%
     ioctl                  3     0.004     0.001     0.001     0.003     36.39%
     access                 1     0.004     0.004     0.004     0.004      0.00%
     uname                  1     0.001     0.001     0.001     0.001      0.00%
     getdents           68393   143.600     0.001     0.002     0.187      0.95%
     fchdir             68371    56.980     0.001     0.001     0.111      0.39%
     arch_prctl             1     0.001     0.001     0.001     0.001      0.00%
     openat             34184    41.737     0.001     0.001     0.102      0.41%
     newfstatat         34184    41.180     0.001     0.001     0.064      0.34%
Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
LPU-Reference: 1438853069-5902-1-git-send-email-milian.wolff@kdab.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>