#!/usr/bin/stap

# usage:   fntimes.stp FUNCTIONPROBE
# e.g.     fntimes.stp 'module("ext4").function("*")'

global mincount = 100      # training: beneath this number of hits, only collect data
global note_percent = 250  # percent beyond maximum-so-far to generate report for
function time() { return gettimeofday_us() }    # time measurement function

global times, entry

probe $1.call {
   entry[probefunc(),tid()] = time()
}

probe $1.return {
   pf=probefunc()
   tid=tid()
   if ([pf,tid] in entry) {       # seen function entry?
      t = time()-entry[pf,tid]    # t: elapsed time
      delete entry[pf,tid]
      if (@count(times[pf]) >= mincount 
          && t >= @max(times[pf]) * note_percent / 100) {   # also consider @avg()
          printf("function %s well over %s time (%d vs %d)\n",
                 pf, "maximum", t, @max(times[pf]))
          # also consider: print_backtrace()
      }
      times[pf] <<< t  # (increments @count, updates @max)
   }
}