bindings/python/examples/sched_switch.py

   1 #!/usr/bin/env python3
   2 # sched_switch.py
   3 #
   4 # Babeltrace example script with sched_switch events
   5 #
   6 # Copyright 2012 EfficiOS Inc.
   7 #
   8 # Author: Danny Serres <danny.serres@efficios.com>
   9 #
  10 # Permission is hereby granted, free of charge, to any person obtaining a copy
  11 # of this software and associated documentation files (the "Software"), to deal
  12 # in the Software without restriction, including without limitation the rights
  13 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14 # copies of the Software, and to permit persons to whom the Software is
  15 # furnished to do so, subject to the following conditions:
  16 #
  17 # The above copyright notice and this permission notice shall be included in
  18 # all copies or substantial portions of the Software.
  19
  20 # The script takes one optional argument (pid)
  21 # The script will read events based on pid and
  22 # print the scheduler switches happening with the process.
  23 # If no arguments are passed, it displays all the scheduler switches.
  24 # This can be used to understand which tasks schedule out the current
  25 # process being traced, and when it gets scheduled in again.
  26 # The trace needs PID context (lttng add-context -k -t pid)
  27
  28 import sys
  29 from babeltrace import *
  30
  31 if len(sys.argv) < 2 or len(sys.argv) > 3:
  32         raise TypeError("Usage: python sched_switch.py [pid] path/to/trace")
  33 elif len(sys.argv) == 3:
  34         usePID = True
  35 else:
  36         usePID = False
  37
  38 traces = TraceCollection()
  39 ret = traces.add_trace(sys.argv[len(sys.argv)-1], "ctf")
  40 if ret is None:
  41         raise IOError("Error adding trace")
  42
  43 for event in traces.events:
  44         while True:
  45                 if event.name == "sched_switch":
  46                         # Getting PID
  47                         pid = event.field_with_scope("pid", CTFScope.STREAM_EVENT_CONTEXT)
  48                         if pid is None:
  49                                 print("ERROR: Missing PID info for sched_switch")
  50                                 break # Next event
  51
  52                         if usePID and (pid != long(sys.argv[1])):
  53                                 break # Next event
  54
  55                         prev_comm = event["prev_comm"]
  56                         prev_tid = event["prev_tid"]
  57                         prev_prio = event["prev_prio"]
  58                         prev_state = event["prev_state"]
  59                         next_comm = event["next_comm"]
  60                         next_tid = event["next_tid"]
  61                         next_prio = event["next_prio"]
  62
  63                         # Output
  64                         print("sched_switch, pid = {}, TS = {}, prev_comm = {},\n\t"
  65                                 "prev_tid = {}, prev_prio = {}, prev_state = {},\n\t"
  66                                 "next_comm = {}, next_tid = {}, next_prio = {}".format(
  67                                 pid, event.timestamp, prev_comm, prev_tid,
  68                                 prev_prio, prev_state, next_comm, next_tid, next_prio))
  69
  70                 break # Next event