4 # Babeltrace example script with sched_switch events
6 # Copyright 2012 EfficiOS Inc.
8 # Author: Danny Serres <danny.serres@efficios.com>
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:
17 # The above copyright notice and this permission notice shall be included in
18 # all copies or substantial portions of the Software.
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)
29 from babeltrace
import *
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:
40 ret
= ctx
.add_trace(sys
.argv
[len(sys
.argv
)-1], "ctf")
42 raise IOError("Error adding trace")
45 bp
= IterPos(SEEK_BEGIN
)
46 ctf_it
= ctf
.Iterator(ctx
, bp
)
49 event
= ctf_it
.read_event()
50 while event
is not None:
52 if event
.get_name() == "sched_switch":
53 # Getting scope definition
54 sco
= event
.get_top_level_scope(ctf
.scope
.STREAM_EVENT_CONTEXT
)
56 print("ERROR: Cannot get definition scope for sched_switch")
60 pid_field
= event
.get_field_with_scope(sco
, "pid")
62 print("ERROR: Missing PID info for sched_switch")
64 pid
= pid_field
.get_value()
65 if usePID
and (pid
!= long(sys
.argv
[1])):
68 sco
= event
.get_top_level_scope(ctf
.scope
.EVENT_FIELDS
)
71 field
= event
.get_field_with_scope(sco
, "prev_comm")
73 print("ERROR: Missing prev_comm context info")
74 prev_comm
= field
.get_value()
77 field
= event
.get_field_with_scope(sco
, "prev_tid")
79 print("ERROR: Missing prev_tid context info")
80 prev_tid
= field
.get_value()
83 field
= event
.get_field_with_scope(sco
, "prev_prio")
85 print("ERROR: Missing prev_prio context info")
86 prev_prio
= field
.get_value()
89 field
= event
.get_field_with_scope(sco
, "prev_state")
91 print("ERROR: Missing prev_state context info")
92 prev_state
= field
.get_value()
95 field
= event
.get_field_with_scope(sco
, "next_comm")
97 print("ERROR: Missing next_comm context info")
98 next_comm
= field
.get_value()
101 field
= event
.get_field_with_scope(sco
, "next_tid")
103 print("ERROR: Missing next_tid context info")
104 next_tid
= field
.get_value()
107 field
= event
.get_field_with_scope(sco
, "next_prio")
109 print("ERROR: Missing next_prio context info")
110 next_prio
= field
.get_value()
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
))
125 event
= ctf_it
.read_event()
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