1d9f671961a608f5454a2b429d972b09a9070505
[babeltrace.git] / 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
39 ctx = Context()
40 ret = ctx.add_trace(sys.argv[len(sys.argv)-1], "ctf")
41 if ret is None:
42 raise IOError("Error adding trace")
43
44 # Setting iterator
45 bp = IterPos(SEEK_BEGIN)
46 ctf_it = CTFReader.Iterator(ctx, bp)
47
48 # Reading events
49 event = ctf_it.read_event()
50 while event is not None:
51 while True:
52 if event.get_name() == "sched_switch":
53 # Getting scope definition
54 sco = event.get_top_level_scope(CTFReader.scope.STREAM_EVENT_CONTEXT)
55 if sco is None:
56 print("ERROR: Cannot get definition scope for sched_switch")
57 break # Next event
58
59 # Getting PID
60 pid_field = event.get_field_with_scope(sco, "pid")
61 if pid_field is None:
62 print("ERROR: Missing PID info for sched_switch")
63 break # Next event
64 pid = pid_field.get_value()
65 if usePID and (pid != long(sys.argv[1])):
66 break # Next event
67
68 sco = event.get_top_level_scope(CTFReader.scope.EVENT_FIELDS)
69
70 # prev_comm
71 field = event.get_field_with_scope(sco, "prev_comm")
72 if field is None:
73 print("ERROR: Missing prev_comm context info")
74 prev_comm = field.get_value()
75
76 # prev_tid
77 field = event.get_field_with_scope(sco, "prev_tid")
78 if field is None:
79 print("ERROR: Missing prev_tid context info")
80 prev_tid = field.get_value()
81
82 # prev_prio
83 field = event.get_field_with_scope(sco, "prev_prio")
84 if field is None:
85 print("ERROR: Missing prev_prio context info")
86 prev_prio = field.get_value()
87
88 # prev_state
89 field = event.get_field_with_scope(sco, "prev_state")
90 if field is None:
91 print("ERROR: Missing prev_state context info")
92 prev_state = field.get_value()
93
94 # next_comm
95 field = event.get_field_with_scope(sco, "next_comm")
96 if field is None:
97 print("ERROR: Missing next_comm context info")
98 next_comm = field.get_value()
99
100 # next_tid
101 field = event.get_field_with_scope(sco, "next_tid")
102 if field is None:
103 print("ERROR: Missing next_tid context info")
104 next_tid = field.get_value()
105
106 # next_prio
107 field = event.get_field_with_scope(sco, "next_prio")
108 if field is None:
109 print("ERROR: Missing next_prio context info")
110 next_prio = field.get_value()
111
112 # Output
113 print("sched_switch, pid = {}, TS = {}, prev_comm = {},\n\t"
114 "prev_tid = {}, prev_prio = {}, prev_state = {},\n\t"
115 "next_comm = {}, next_tid = {}, next_prio = {}".format(
116 pid, event.get_timestamp(), prev_comm, prev_tid,
117 prev_prio, prev_state, next_comm, next_tid, next_prio))
118
119 break # Next event
120
121 # Next event
122 ret = ctf_it.next()
123 if ret < 0:
124 break
125 event = ctf_it.read_event()
126
127 del ctf_it
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