Documentation: clarify event name in lttng-ust.3

[lttng-ust.git] / doc / man / lttng-ust.3

diff --git a/doc/man/lttng-ust.3 b/doc/man/lttng-ust.3
index 26841d02e3f89ebf6ba9acdeac0b74867360c30f..0c8405fc676d4b9795a2890b344283ff4d217139 100644 (file)
--- a/doc/man/lttng-ust.3
+++ b/doc/man/lttng-ust.3
@@ -17,7 +17,38 @@ port of the low-overhead tracing capabilities of the LTTng kernel tracer
 to user-space. The library "liblttng-ust" enables tracing of
 applications and libraries.
 
-.SH "USAGE"
+.SH "USAGE WITH TRACEF"
+.PP
+The simplest way to add instrumentation to your code is by far the
+tracef() API. To do it, in a nutshell:
+
+1) #include <lttng/tracef.h>
+
+2) /* in your code, use like a printf */
+   tracef("my message, this integer %d", 1234);
+
+3) Link your program against liblttng-ust.so.
+
+4) Enable UST events when tracing with the following sequence of commands
+   from lttng-tools:
+
+   lttng create
+   lttng enable-event -u -a
+   lttng start
+   [... run your program ...]
+   lttng stop
+   lttng view
+
+That's it!
+
+If you want to have more flexibility and control on the event names,
+payload typing, etc, you can continue reading on and use the tracepoints
+below. "tracef()" is there for quick and dirty ad hoc instrumentation,
+whereas tracepoint.h is meant for thorough instrumentation of a code
+base to be integrated with an upstream project.
+.PP
+
+.SH "USAGE WITH TRACEPOINT"
 .PP
 The simple way to generate the lttng-ust tracepoint probes is to use the
 lttng-gen-tp(1) tool. See the lttng-gen-tp(1) manpage for explanation.
@@ -33,9 +64,13 @@ script, through an example:
 .nf
 
 To create a tracepoint provider, within a build tree similar to
-examples/easy-ust installed with lttng-ust documentation, a
-sample_component_provider.h for the general layout. This manpage will
-focus on the various types that can be recorded into a trace event:
+examples/easy-ust installed with lttng-ust documentation, see
+sample_component_provider.h for the general layout. You will need to
+define TRACEPOINT_CREATE_PROBES before including your tracepoint
+provider probe in one source file of your application. See tp.c from
+easy-ust for an example of a tracepoint probe source file. This manpage
+will focus on the various types that can be recorded into a trace
+event:
 
 TRACEPOINT_EVENT(
        /*
@@ -57,11 +92,11 @@ TRACEPOINT_EVENT(
        sample_component,
 
        /*
-        * tracepoint name, same format as sample provider. Does not
-        * need to be declared before. in this case the name is
-        * "message"
+        * tracepoint name, characters permitted follow the same
+        * constraints as the provider name. The name of this example
+        * event is "sample_event".
         */
-       message,
+       sample_event,
 
        /*
         * TP_ARGS macro contains the arguments passed for the tracepoint
@@ -230,7 +265,7 @@ debug information.
    debug information with line-level scope (TRACEPOINT_EVENT default)
 
    TRACE_DEBUG           14
-   debug-level message (trace_printf default)
+   debug-level message
 
 See lttng(1) for information on how to use LTTng-UST loglevels.
 
@@ -342,6 +377,13 @@ Virtual process ID: process ID as seen from the point of view of the
 process namespace.
 .PP
 
+.PP
+.IP "ip"
+Instruction pointer: Enables recording of the exact location where a tracepoint
+was emitted. Can be used to reverse-lookup the source location that caused the
+event to be emitted.
+.PP
+
 .PP
 .IP "procname"
 Thread name, as set by exec() or prctl(). It is recommended that
@@ -355,6 +397,29 @@ Pthread identifier. Can be used on architectures where pthread_t maps
 nicely to an unsigned long type.
 .PP
 
+.SH "BASE ADDRESS STATEDUMP"
+
+.PP
+If an application that uses liblttng-ust.so becomes part of a session,
+information about its currently loaded shared objects will be traced to the
+session at session-enable time. To record this information, the following event
+needs to be enabled:
+.PP
+.IP "ust_baddr_statedump:soinfo"
+This event is used to trace a currently loaded shared object. The base address
+(where the dynamic linker has placed the shared object) is recorded in the
+"baddr" field. The path to the shared object gets recorded in the
+"sopath" field (as string). The file size of the loaded object (in
+bytes) is recorded to the "size" field and its time of last modification
+(in seconds since Epoch) is recorded in the "mtime" field.
+.PP
+If the event above is enabled, a series of "ust_baddr_statedump:soinfo"
+events is recorded at session-enable time. It represents the state of
+currently loaded shared objects for the traced process. If this
+information gets combined with the lttng-ust-dl(3) instrumentation, all
+aspects of dynamic loading that are relevant for symbol and
+line number lookup are traced by LTTng.
+.PP
 .SH "ENVIRONMENT VARIABLES"
 
 .PP
@@ -371,12 +436,15 @@ specified in milliseconds. The value 0 means "don't wait". The value
 recommended for applications with time constraints on the process
 startup time.
 .PP
+.IP "LTTNG_UST_WITHOUT_BADDR_STATEDUMP"
+Prevent liblttng-ust to perform a base-address statedump on session-enable.
+.PP
 
 .SH "SEE ALSO"
 
 .PP
 lttng-gen-tp(1), lttng(1), babeltrace(1), lttng-ust-cyg-profile(3),
-lttng-sessiond(8)
+lttng-ust-dl(3), lttng-sessiond(8)
 .PP
 
 .SH "COMPATIBILITY"