Linux Perf
futex-contention.py
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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, callchain,
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, callchain,
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 
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 
def syscalls__sys_exit_futex(event, ctxt, cpu, s, ns, tid, comm, callchain, nr, ret)
static unsigned int nsecs
Definition: futex-hash.c:32
def syscalls__sys_enter_futex(event, ctxt, cpu, s, ns, tid, comm, callchain, nr, uaddr, op, val, utime, uaddr2, val3)
def add_stats(dict, key, value)
Definition: Util.py:35