-c      Count time, calls, and errors for each system call and report a
        summary on program exit.  On Linux, this attempts to show system
        time (CPU  time  spent  running in the kernel) independent of wall
        clock time.  If -c is used with -f or -F (below), only aggregate
        totals for all traced processes are kept.

$ strace -c systemctl list-unit-files --type=service
...
...
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 51.81    0.001831        1831         1           waitid
  8.15    0.000288           7        39           mmap
  7.89    0.000279          19        15           read
  6.11    0.000216           8        26           mprotect
  4.56    0.000161          11        15           open
  2.91    0.000103         103         1           connect
  2.24    0.000079          79         1           clone
  2.15    0.000076          38         2           statfs
  2.01    0.000071           4        19           close
  1.95    0.000069           5        13           poll
  1.90    0.000067           5        14         2 recvmsg
  1.70    0.000060           4        16           fstat
  0.88    0.000031           8         4         3 stat
  0.82    0.000029          29         1           socket
  0.65    0.000023           8         3           munmap
  0.57    0.000020           5         4           sendto
  0.42    0.000015           5         3           ioctl
  0.40    0.000014           7         2           lstat
  0.40    0.000014           7         2           sendmsg
  0.34    0.000012           4         3           brk
  0.23    0.000008           8         1           pipe
  0.23    0.000008           4         2           fcntl
  0.20    0.000007           4         2           rt_sigaction
  0.20    0.000007           7         1         1 access
  0.20    0.000007           4         2           geteuid
  0.17    0.000006           6         1           execve
  0.14    0.000005           5         1           getsockname
  0.11    0.000004           4         1           dup2
  0.11    0.000004           4         1           getresuid
  0.11    0.000004           4         1           getresgid
  0.11    0.000004           4         1           arch_prctl
  0.08    0.000003           3         1           rt_sigprocmask
  0.08    0.000003           3         1           getrlimit
  0.08    0.000003           3         1           set_tid_address
  0.08    0.000003           3         1           set_robust_list
  0.00    0.000000           0         4           write
  0.00    0.000000           0         1           kill
------ ----------- ----------- --------- --------- ----------------
100.00    0.003534                   207         6 total