# futex contention
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# (c) 2010, Arnaldo Carvalho de Melo <acme@redhat.com>
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# Licensed under the terms of the GNU GPL License version 2
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#
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# Translation of:
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#
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# http://sourceware.org/systemtap/wiki/WSFutexContention
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#
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# to perf python scripting.
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#
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# Measures futex contention
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import os, sys
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sys.path.append(os.environ['PERF_EXEC_PATH'] + '/scripts/python/Perf-Trace-Util/lib/Perf/Trace')
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from Util import *
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process_names = {}
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thread_thislock = {}
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thread_blocktime = {}
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lock_waits = {} # long-lived stats on (tid,lock) blockage elapsed time
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process_names = {} # long-lived pid-to-execname mapping
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def syscalls__sys_enter_futex(event, ctxt, cpu, s, ns, tid, comm, callchain,
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nr, uaddr, op, val, utime, uaddr2, val3):
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cmd = op & FUTEX_CMD_MASK
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if cmd != FUTEX_WAIT:
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return # we don't care about originators of WAKE events
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process_names[tid] = comm
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thread_thislock[tid] = uaddr
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thread_blocktime[tid] = nsecs(s, ns)
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def syscalls__sys_exit_futex(event, ctxt, cpu, s, ns, tid, comm, callchain,
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nr, ret):
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if thread_blocktime.has_key(tid):
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elapsed = nsecs(s, ns) - thread_blocktime[tid]
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add_stats(lock_waits, (tid, thread_thislock[tid]), elapsed)
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del thread_blocktime[tid]
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del thread_thislock[tid]
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def trace_begin():
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print "Press control+C to stop and show the summary"
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def trace_end():
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for (tid, lock) in lock_waits:
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min, max, avg, count = lock_waits[tid, lock]
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print "%s[%d] lock %x contended %d times, %d avg ns" % \
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(process_names[tid], tid, lock, count, avg)
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