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 from __future__ import print_function
14
15 import os
16 import sys
17 sys.path.append(os.environ['PERF_EXEC_PATH'] +
18 '/scripts/python/Perf-Trace-Util/lib/Perf/Trace')
19 from Util import *
20
21 process_names = {}
22 thread_thislock = {}
23 thread_blocktime = {}
24
25 lock_waits = {} # long-lived stats on (tid,lock) blockage elapsed time
26 process_names = {} # long-lived pid-to-execname mapping
27
28
29 def syscalls__sys_enter_futex(event, ctxt, cpu, s, ns, tid, comm, callchain,
30 nr, uaddr, op, val, utime, uaddr2, val3):
31 cmd = op & FUTEX_CMD_MASK
32 if cmd != FUTEX_WAIT:
33 return # we don't care about originators of WAKE events
34
35 process_names[tid] = comm
36 thread_thislock[tid] = uaddr
37 thread_blocktime[tid] = nsecs(s, ns)
38
39
40 def syscalls__sys_exit_futex(event, ctxt, cpu, s, ns, tid, comm, callchain,
41 nr, ret):
42 if tid in thread_blocktime:
43 elapsed = nsecs(s, ns) - thread_blocktime[tid]
44 add_stats(lock_waits, (tid, thread_thislock[tid]), elapsed)
45 del thread_blocktime[tid]
46 del thread_thislock[tid]
47
48
49 def trace_begin():
50 print("Press control+C to stop and show the summary")
51
52
53 def trace_end():
54 for (tid, lock) in lock_waits:
55 min, max, avg, count = lock_waits[tid, lock]
56 print("%s[%d] lock %x contended %d times, %d avg ns [max: %d ns, min %d ns]" %
57 (process_names[tid], tid, lock, count, avg, max, min))
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