tools/perf/scripts/python/futex-contention.py

   1 # futex contention
   2 # (c) 2010, Arnaldo Carvalho de Melo <acme@redhat.com>
   3 # Licensed under the terms of the GNU GPL License version 2
   4 #
   5 # Translation of:
   6 #
   7 # http://sourceware.org/systemtap/wiki/WSFutexContention
   8 #
   9 # to perf python scripting.
  10 #
  11 # Measures futex contention
  12
  13 import os, sys
  14 sys.path.append(os.environ['PERF_EXEC_PATH'] + '/scripts/python/Perf-Trace-Util/lib/Perf/Trace')
  15 from Util import *
  16
  17 process_names = {}
  18 thread_thislock = {}
  19 thread_blocktime = {}
  20
  21 lock_waits = {} # long-lived stats on (tid,lock) blockage elapsed time
  22 process_names = {} # long-lived pid-to-execname mapping
  23
  24 def syscalls__sys_enter_futex(event, ctxt, cpu, s, ns, tid, comm,
  25                               nr, uaddr, op, val, utime, uaddr2, val3):
  26         cmd = op & FUTEX_CMD_MASK
  27         if cmd != FUTEX_WAIT:
  28                 return # we don't care about originators of WAKE events
  29
  30         process_names[tid] = comm
  31         thread_thislock[tid] = uaddr
  32         thread_blocktime[tid] = nsecs(s, ns)
  33
  34 def syscalls__sys_exit_futex(event, ctxt, cpu, s, ns, tid, comm,
  35                              nr, ret):
  36         if thread_blocktime.has_key(tid):
  37                 elapsed = nsecs(s, ns) - thread_blocktime[tid]
  38                 add_stats(lock_waits, (tid, thread_thislock[tid]), elapsed)
  39                 del thread_blocktime[tid]
  40                 del thread_thislock[tid]
  41
  42 def trace_begin():
  43         print "Press control+C to stop and show the summary"
  44
  45 def trace_end():
  46         for (tid, lock) in lock_waits:
  47                 min, max, avg, count = lock_waits[tid, lock]
  48                 print "%s[%d] lock %x contended %d times, %d avg ns" % \
  49                       (process_names[tid], tid, lock, count, avg)
  50