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 SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  23 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  26 # SOFTWARE.
  27
  28 # The script takes one optional argument (pid)
  29 # The script will read events based on pid and
  30 # print the scheduler switches happening with the process.
  31 # If no arguments are passed, it displays all the scheduler switches.
  32 # This can be used to understand which tasks schedule out the current
  33 # process being traced, and when it gets scheduled in again.
  34 # The trace needs PID context (lttng add-context -k -t pid)
  35
  36 import sys
  37 from babeltrace import *
  38
  39 if len(sys.argv) < 2 or len(sys.argv) > 3:
  40     raise TypeError("Usage: python sched_switch.py [pid] path/to/trace")
  41 elif len(sys.argv) == 3:
  42     filterPID = True
  43 else:
  44     filterPID = False
  45
  46 traces = TraceCollection()
  47 ret = traces.add_trace(sys.argv[len(sys.argv) - 1], "ctf")
  48 if ret is None:
  49     raise IOError("Error adding trace")
  50
  51 for event in traces.events:
  52     if event.name != "sched_switch":
  53         continue
  54
  55     # Getting PID
  56     pid = event.field_with_scope("pid", CTFScope.STREAM_EVENT_CONTEXT)
  57     if pid is None:
  58         print("ERROR: Missing PID info for sched_switch")
  59         continue  # Next event
  60
  61     if filterPID and (pid != long(sys.argv[1])):
  62         continue  # Next event
  63
  64     prev_comm = event["prev_comm"]
  65     prev_tid = event["prev_tid"]
  66     prev_prio = event["prev_prio"]
  67     prev_state = event["prev_state"]
  68     next_comm = event["next_comm"]
  69     next_tid = event["next_tid"]
  70     next_prio = event["next_prio"]
  71
  72     # Output
  73     print("sched_switch, pid = {}, TS = {}, prev_comm = {},\n\t"
  74           "prev_tid = {}, prev_prio = {}, prev_state = {},\n\t"
  75           "next_comm = {}, next_tid = {}, next_prio = {}".format(
  76               pid, event.timestamp, prev_comm, prev_tid,
  77               prev_prio, prev_state, next_comm, next_tid, next_prio))