# cache_grow.stp
# This script captures tallies stack back traces each time the slab cache
# size is increased. The program is run with the following command:
#
# stap  cache_grow.stp
#
# When the script completes it prints out top twenty executable that
# caused slabs to grow. This is followed by stack backtraces showing path
# in kernel to the cache_grow function.

global stats, stacks

probe kernel.function("cache_grow") {
  name = kernel_string($cachep->name)
  exec = execname()
  stats[exec, name] <<< 1
  stacks[exec, name, backtrace()] <<< 1
}


probe begin {
  printf("Type ctrl-c to stop script, and print out data (top 20 lists)\n")
}

probe end {
  printf("Number of cache_grow called by process and slab name\n")
  foreach ([exec, name] in stats- limit 20) {
    printf("%s, %s:\t%d\n", exec, name, @count(stats[exec, name]))
  }

  printf("\nBacktrace of processes when cache_grow called\n")
  foreach ([exec, cache, bt] in stacks- limit 20) {
    printf("Exec: %s Slab name: %s  Count: %d\n",
       exec, cache, @count(stacks[exec, cache, bt]))
    print_stack(bt)
    printf("\n-------------------------------------------------------\n\n")
  }
}