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c3947c25 | 1 | .\" generated with Ronn/v0.5 |
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2 | .\" http://github.com/rtomayko/ronn/ |
3 | . | |
c3947c25 | 4 | .TH "USTCTL" "1" "May 2010" "" "" |
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5 | . |
6 | .SH "NAME" | |
7 | \fBustctl\fR \-\- a program to control the tracing of userspace applications | |
8 | . | |
9 | .SH "SYNOPSIS" | |
10 | \fBustctl\fR [\fIcommand\fR] [\fIPIDs\fR]... | |
11 | . | |
12 | .SH "DESCRIPTION" | |
c3947c25 | 13 | \fBustctl\fR is a program to control the tracing of userspace applications. It can |
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14 | list markers, start the tracing, stop the tracing, enable/disable markers, etc. |
15 | . | |
16 | .SH "OPTIONS" | |
17 | These programs follow the usual GNU command line syntax, with long options | |
18 | starting with two dashes(`\-'). A summary of options is included below. | |
19 | . | |
20 | .TP | |
21 | \fB\-h\fR, \fB\-\-help\fR | |
22 | Show summary of options. | |
23 | . | |
24 | .TP | |
25 | \fB\-\-create\-trace\fR | |
26 | Create trace. | |
27 | . | |
28 | .TP | |
29 | \fB\-\-alloc\-trace\fR | |
c3947c25 | 30 | Allocate trace. |
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31 | . |
32 | .TP | |
33 | \fB\-\-start\-trace\fR | |
34 | Start tracing. | |
35 | . | |
36 | .TP | |
37 | \fB\-\-stop\-trace\fR | |
38 | Stop tracing. | |
39 | . | |
40 | .TP | |
41 | \fB\-\-destroy\-trace\fR | |
42 | Destroy the trace. | |
43 | . | |
44 | .TP | |
45 | \fB\-\-set\-subbuf\-size\fR \fICHANNEL\fR/\fIbytes\fR | |
c3947c25 | 46 | Set the size of subbuffers in CHANNEL. |
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47 | . |
48 | .TP | |
49 | \fB\-\-set\-subbuf\-num\fR \fICHANNEL\fR | |
c3947c25 | 50 | Set the number of subbuffers per buffer for CHANNEL. Must be a power of 2. |
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51 | . |
52 | .TP | |
53 | \fB\-\-get\-subbuf\-size\fR \fICHANNEL\fR | |
c3947c25 | 54 | Print the size of subbuffers per buffer for CHANNEL. |
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55 | . |
56 | .TP | |
57 | \fB\-\-get\-subbuf\-num\fR \fICHANNEL\fR | |
c3947c25 | 58 | Print the number of subbuffers per buffer for CHANNEL. |
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59 | . |
60 | .TP | |
61 | \fB\-\-enable\-marker\fR \fICHANNEL\fR/\fIMARKER\fR | |
62 | Enable a marker. | |
63 | . | |
64 | .TP | |
65 | \fB\-\-disable\-marker\fR \fICHANNEL\fR/\fIMARKER\fR | |
66 | Disable a marker. | |
67 | . | |
68 | .TP | |
69 | \fB\-\-list\-markers\fR | |
70 | List the markers of the process, their state and format string. | |
71 | . | |
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72 | .SH "LIFE CYCLE OF A TRACE" |
73 | Typically, the first step is to enable markers with \fB\-\-enable\-marker\fR. An | |
74 | enabled marker generates an event when the control flow passes over it | |
75 | (assuming the trace is recording). A disabled marker produces nothing. Enabling | |
76 | and disabling markers may however be done at any point, including while the | |
77 | trace is being recorded. | |
78 | . | |
79 | .P | |
80 | In order to record events, a trace is first created with \fB\-\-create\-trace\fR. At | |
81 | this point, the subbuffer count and size may be changed with \fB\-\-set\-subbuf\-num\fR | |
82 | and \fB\-\-set\-subbuf\-size\fR. | |
83 | . | |
84 | .P | |
85 | Afterward, the trace may be allocated with \fB\-\-alloc\-trace\fR. This allocates the | |
86 | buffers in memory, so once this is done, the subbuffer size and count can not | |
87 | be changed. Trace allocation also causes the daemon to connect to the trace | |
88 | buffers and wait for data to arrive. Explicit allocation is optional, as it is | |
89 | done automatically at trace start. | |
90 | . | |
91 | .P | |
92 | The trace may then be started with \fB\-\-start\-trace\fR. This results in events | |
93 | being recorded in the buffer. The daemon automatically collects these events. | |
94 | . | |
95 | .P | |
96 | The trace may be stopped with \fB\-\-stop\-trace\fR, either definitely after all the | |
97 | wanted information is collected, or temporarily, before being started again | |
98 | with \fB\-\-start\-trace\fR. This results in effectively "pausing" the recording. | |
99 | . | |
100 | .P | |
101 | Finally, when \fB\-\-destroy\-trace\fR is used, the trace buffers are unallocated. | |
102 | However, the memory may not be effectively freed until the daemon finishes to | |
103 | collect them. | |
104 | . | |
105 | .SH "STRUCTURE OF A TRACE" | |
106 | Each instrumentation point that is added in a program is associated to a | |
107 | channel. | |
108 | . | |
109 | .P | |
110 | Trace events are put in buffers. There is one buffer per channel, per cpu. | |
111 | For example, on a system with 4 cores and tracing an application with 3 | |
112 | channels, there will be 12 buffers in total. The content of each of these | |
113 | buffers is put in a distinct file in the trace directory. For example, the \fBmetadata_2\fR file contains the data that was extracted from the buffer that | |
114 | contained the events from the metadata channel and having occurred on cpu 2. | |
115 | . | |
116 | .P | |
117 | In memory, each buffer is divided in subbuffers. Subbuffers are equally\-sized, | |
118 | contiguous parts of a buffer. The size of a buffer is equal to the number of | |
119 | subbuffers it contains times the size of each subbuffer. When a subbuffer is | |
120 | full, it is collected by the daemon while the others are filled. If, however, | |
121 | the buffer size is too small, buffer overflows may occur and result in event | |
122 | loss. By default, the number of subbuffers per buffer is 2. Subbuffer size | |
123 | for a given channel may be chosen with \fB\-\-set\-subbuf\-size\fR while the subbuffer | |
124 | count is set with \fB\-\-set\-subbuf\-num\fR. | |
125 | . | |
126 | .SH "SEE ALSO" | |
127 | usttrace(1), ustd(1) | |
128 | . | |
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129 | .SH "AUTHOR" |
130 | \fBustctl\fR was written by Pierre\-Marc Fournier. | |
131 | . | |
132 | .P | |
133 | This manual page was written by Jon Bernard <jbernard@debian.org>, for | |
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134 | the Debian project (and may be used by others). It was updated by Pierre\-Marc |
135 | Fournier. |