documentation update

[ust.git] / doc / man / ustctl.1

diff --git a/doc/man/ustctl.1 b/doc/man/ustctl.1
index bb942ae0a5de53db5d736016aa52d2f5c726d525..e77251d4faad33b57782765c9e7e7ef3bb42131c 100644 (file)
--- a/doc/man/ustctl.1
+++ b/doc/man/ustctl.1
@@ -1,7 +1,7 @@
-.\" generated with Ronn/v0.4.1
+.\" generated with Ronn/v0.5
 .\" http://github.com/rtomayko/ronn/
 .
-.TH "USTCTL" "1" "March 2010" "" ""
+.TH "USTCTL" "1" "May 2010" "" ""
 .
 .SH "NAME"
 \fBustctl\fR \-\- a program to control the tracing of userspace applications
@@ -10,7 +10,7 @@
 \fBustctl\fR [\fIcommand\fR] [\fIPIDs\fR]...
 .
 .SH "DESCRIPTION"
-\fBustclt\fR is a program to control the tracing of userspace applications. It can
+\fBustctl\fR is a program to control the tracing of userspace applications. It can
 list markers, start the tracing, stop the tracing, enable/disable markers, etc.
 .
 .SH "OPTIONS"
@@ -27,7 +27,7 @@ Create trace.
 .
 .TP
 \fB\-\-alloc\-trace\fR
-Alloc trace.
+Allocate trace.
 .
 .TP
 \fB\-\-start\-trace\fR
@@ -43,19 +43,19 @@ Destroy the trace.
 .
 .TP
 \fB\-\-set\-subbuf\-size\fR \fICHANNEL\fR/\fIbytes\fR
-Set the size of subbuffers per channel.
+Set the size of subbuffers in CHANNEL.
 .
 .TP
 \fB\-\-set\-subbuf\-num\fR \fICHANNEL\fR
-Set the number of subbuffers per channel.
+Set the number of subbuffers per buffer for CHANNEL. Must be a power of 2.
 .
 .TP
 \fB\-\-get\-subbuf\-size\fR \fICHANNEL\fR
-Get the size of subbuffers per channel.
+Print the size of subbuffers per buffer for CHANNEL.
 .
 .TP
 \fB\-\-get\-subbuf\-num\fR \fICHANNEL\fR
-Get the number of subbuffers per channel.
+Print the number of subbuffers per buffer for CHANNEL.
 .
 .TP
 \fB\-\-enable\-marker\fR \fICHANNEL\fR/\fIMARKER\fR
@@ -69,9 +69,67 @@ Disable a marker.
 \fB\-\-list\-markers\fR
 List the markers of the process, their state and format string.
 .
+.SH "LIFE CYCLE OF A TRACE"
+Typically, the first step is to enable markers with \fB\-\-enable\-marker\fR. An
+enabled marker generates an event when the control flow passes over it
+(assuming the trace is recording). A disabled marker produces nothing. Enabling
+and disabling markers may however be done at any point, including while the
+trace is being recorded.
+.
+.P
+In order to record events, a trace is first created with \fB\-\-create\-trace\fR. At
+this point, the subbuffer count and size may be changed with \fB\-\-set\-subbuf\-num\fR
+and \fB\-\-set\-subbuf\-size\fR.
+.
+.P
+Afterward, the trace may be allocated with \fB\-\-alloc\-trace\fR. This allocates the
+buffers in memory, so once this is done, the subbuffer size and count can not
+be changed. Trace allocation also causes the daemon to connect to the trace
+buffers and wait for data to arrive. Explicit allocation is optional, as it is
+done automatically at trace start.
+.
+.P
+The trace may then be started with \fB\-\-start\-trace\fR. This results in events
+being recorded in the buffer. The daemon automatically collects these events.
+.
+.P
+The trace may be stopped with \fB\-\-stop\-trace\fR, either definitely after all the
+wanted information is collected, or temporarily, before being started again
+with \fB\-\-start\-trace\fR. This results in effectively "pausing" the recording.
+.
+.P
+Finally, when \fB\-\-destroy\-trace\fR is used, the trace buffers are unallocated.
+However, the memory may not be effectively freed until the daemon finishes to
+collect them.
+.
+.SH "STRUCTURE OF A TRACE"
+Each instrumentation point that is added in a program is associated to a
+channel.
+.
+.P
+Trace events are put in buffers. There is one buffer per channel, per cpu.
+For example, on a system with 4 cores and tracing an application with 3
+channels, there will be 12 buffers in total. The content of each of these
+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
+contained the events from the metadata channel and having occurred on cpu 2.
+.
+.P
+In memory, each buffer is divided in subbuffers. Subbuffers are equally\-sized,
+contiguous parts of a buffer. The size of a buffer is equal to the number of
+subbuffers it contains times the size of each subbuffer. When a subbuffer is
+full, it is collected by the daemon while the others are filled. If, however,
+the buffer size is too small, buffer overflows may occur and result in event
+loss. By default, the number of subbuffers per buffer is 2. Subbuffer size
+for a given channel may be chosen with \fB\-\-set\-subbuf\-size\fR while the subbuffer
+count is set with \fB\-\-set\-subbuf\-num\fR.
+.
+.SH "SEE ALSO"
+usttrace(1), ustd(1)
+.
 .SH "AUTHOR"
 \fBustctl\fR was written by Pierre\-Marc Fournier.
 .
 .P
 This manual page was written by Jon Bernard <jbernard@debian.org>, for
-the Debian project (and may be used by others).
+the Debian project (and may be used by others). It was updated by Pierre\-Marc
+Fournier.