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1 | # sched_switch.py |
2 | # | |
3 | # Babeltrace example script with sched_switch events | |
4 | # | |
5 | # Copyright 2012 EfficiOS Inc. | |
6 | # | |
7 | # Author: Danny Serres <danny.serres@efficios.com> | |
8 | # | |
9 | # Permission is hereby granted, free of charge, to any person obtaining a copy | |
10 | # of this software and associated documentation files (the "Software"), to deal | |
11 | # in the Software without restriction, including without limitation the rights | |
12 | # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
13 | # copies of the Software, and to permit persons to whom the Software is | |
14 | # furnished to do so, subject to the following conditions: | |
15 | # | |
16 | # The above copyright notice and this permission notice shall be included in | |
17 | # all copies or substantial portions of the Software. | |
18 | ||
19 | # The script takes one optional argument (pid) | |
20 | # The script will read events based on pid and | |
21 | # print the scheduler switches happening with the process. | |
22 | # If no arguments are passed, it displays all the scheduler switches. | |
23 | # This can be used to understand which tasks schedule out the current | |
24 | # process being traced, and when it gets scheduled in again. | |
25 | # The trace needs PID context (lttng add-context -k -t pid) | |
26 | ||
27 | import sys | |
28 | from babeltrace import * | |
29 | ||
30 | if len(sys.argv) < 2 or len(sys.argv) > 3: | |
31 | raise TypeError("Usage: python sched_switch.py [pid] path/to/trace") | |
32 | elif len(sys.argv) == 3: | |
33 | usePID = True | |
34 | else: | |
35 | usePID = False | |
36 | ||
37 | ||
38 | ctx = Context() | |
39 | ret = ctx.add_trace(sys.argv[len(sys.argv)-1], "ctf") | |
40 | if ret is None: | |
41 | raise IOError("Error adding trace") | |
42 | ||
43 | # Setting iterator | |
44 | bp = IterPos(SEEK_BEGIN) | |
45 | ctf_it = ctf.Iterator(ctx, bp) | |
46 | ||
47 | # Reading events | |
48 | event = ctf_it.read_event() | |
49 | while event is not None: | |
50 | while True: | |
51 | if event.get_name() == "sched_switch": | |
52 | # Getting scope definition | |
53 | sco = event.get_top_level_scope(ctf.scope.STREAM_EVENT_CONTEXT) | |
54 | if sco is None: | |
55 | print("ERROR: Cannot get definition scope for sched_switch") | |
56 | break # Next event | |
57 | ||
58 | # Getting PID | |
59 | pid_field = event.get_field(sco, "_pid") | |
60 | pid = pid_field.get_int64() | |
61 | ||
62 | if ctf.field_error(): | |
63 | print("ERROR: Missing PID info for sched_switch") | |
64 | break # Next event | |
65 | ||
66 | if usePID and (pid != long(sys.argv[1])): | |
67 | break # Next event | |
68 | ||
69 | sco = event.get_top_level_scope(ctf.scope.EVENT_FIELDS) | |
70 | ||
71 | # prev_comm | |
72 | field = event.get_field(sco, "_prev_comm") | |
73 | prev_comm = field.get_char_array() | |
74 | if ctf.field_error(): | |
75 | print("ERROR: Missing prev_comm context info") | |
76 | ||
77 | # prev_tid | |
78 | field = event.get_field(sco, "_prev_tid") | |
79 | prev_tid = field.get_int64() | |
80 | if ctf.field_error(): | |
81 | print("ERROR: Missing prev_tid context info") | |
82 | ||
83 | # prev_prio | |
84 | field = event.get_field(sco, "_prev_prio") | |
85 | prev_prio = field.get_int64() | |
86 | if ctf.field_error(): | |
87 | print("ERROR: Missing prev_prio context info") | |
88 | ||
89 | # prev_state | |
90 | field = event.get_field(sco, "_prev_state") | |
91 | prev_state = field.get_int64() | |
92 | if ctf.field_error(): | |
93 | print("ERROR: Missing prev_state context info") | |
94 | ||
95 | # next_comm | |
96 | field = event.get_field(sco, "_next_comm") | |
97 | next_comm = field.get_char_array() | |
98 | if ctf.field_error(): | |
99 | print("ERROR: Missing next_comm context info") | |
100 | ||
101 | # next_tid | |
102 | field = event.get_field(sco, "_next_tid") | |
103 | next_tid = field.get_int64() | |
104 | if ctf.field_error(): | |
105 | print("ERROR: Missing next_tid context info") | |
106 | ||
107 | # next_prio | |
108 | field = event.get_field(sco, "_next_prio") | |
109 | next_prio = field.get_int64() | |
110 | if ctf.field_error(): | |
111 | print("ERROR: Missing next_prio context info") | |
112 | ||
113 | # Output | |
114 | print("sched_switch, pid = {}, TS = {}, prev_comm = {},\n\t" | |
115 | "prev_tid = {}, prev_prio = {}, prev_state = {},\n\t" | |
116 | "next_comm = {}, next_tid = {}, next_prio = {}".format( | |
117 | pid, event.get_timestamp(), prev_comm, prev_tid, | |
118 | prev_prio, prev_state, next_comm, next_tid, next_prio)) | |
119 | ||
120 | break # Next event | |
121 | ||
122 | # Next event | |
123 | ret = ctf_it.next() | |
124 | if ret < 0: | |
125 | break | |
126 | event = ctf_it.read_event() | |
127 | ||
128 | del ctf_it |