projects/linux·blob 04480094 · refs

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1# futex contention
2# (c) 2010, Arnaldo Carvalho de Melo <[email protected]>
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
13import os, sys
14sys.path.append(os.environ['PERF_EXEC_PATH'] + '/scripts/python/Perf-Trace-Util/lib/Perf/Trace')
15from Util import *
16
17process_names = {}
18thread_thislock = {}
19thread_blocktime = {}
20
21lock_waits = {} # long-lived stats on (tid,lock) blockage elapsed time
22process_names = {} # long-lived pid-to-execname mapping
23
24def 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
34def 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
42def trace_begin():
43 print "Press control+C to stop and show the summary"
44
45def 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