fntimes.stp - Show Functions Taking Longer Than Usual

  The fntimes.stp script monitors the execution time history of a given
  function family (assumed non-recursive).  Each time (beyond a warmup
  interval) is then compared to the historical maximum.  If it exceeds
  a certain threshold (250%), a message is printed.

$ stap fntimes.stp 'kernel.function("sys_*")' -T 7

function SyS_ioctl well over maximum time (32 vs 12)
function SyS_open well over maximum time (2832 vs 188)
function SyS_newfstat well over maximum time (5 vs 2)
function SyS_mmap_pgoff well over maximum time (282 vs 12)
function SyS_mmap well over maximum time (286 vs 15)
function SyS_access well over maximum time (35 vs 11)
function SyS_access well over maximum time (92 vs 35)
function SyS_mprotect well over maximum time (44 vs 13)
function SyS_futex well over maximum time (9753 vs 3260)
function SyS_newstat well over maximum time (4882 vs 133)
function SyS_recvmsg well over maximum time (607 vs 44)
function SyS_futex well over maximum time (55896 vs 9753)
function SyS_futex well over maximum time (500089 vs 55927)
function SyS_poll well over maximum time (832629 vs 53308)

Getting no output is not a bad thing; it means that means that functions
did not exceed the threshold.

This output was gathered by running ls repeatedly in another terminal
a few seconds after the script started.