X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=doc%2Fman%2Flttng-ust.3;h=61efa5094611d39859a88761dff90cb4eabfccc6;hb=fc0ec7f9751f28ca83d7452972e1aa1a41f6e73e;hp=55de9fd2d88cea5de0cd1fa04f6eba46c4371efd;hpb=f6df8626c40e58c39e83215a5bdbdf7a29038c35;p=lttng-ust.git

diff --git a/doc/man/lttng-ust.3 b/doc/man/lttng-ust.3
index 55de9fd2..61efa509 100644
--- a/doc/man/lttng-ust.3
+++ b/doc/man/lttng-ust.3
@@ -17,7 +17,35 @@ 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 the UST event "lttng_ust_tracef:event" when tracing with the
+   following sequence of commands from lttng-tools:
+
+   lttng create; lttng enable-event -u "lttng_ust_tracef:event"; 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.
@@ -366,9 +394,13 @@ Pthread identifier. Can be used on architectures where pthread_t maps
 nicely to an unsigned long type.
 .PP
 
-.SH "BASE ADDRESS STATEDUMP"
+.SH "BASE ADDRESS STATEDUMP (Experimental feature)"
 
 .PP
+Warning: This is an experimental feature known to cause deadlocks when the
+traced application uses fork, clone or daemon. Only use it for debugging and
+testing.  Do NOT use it in production.
+
 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
@@ -377,16 +409,17 @@ needs to be enabled:
 .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, that represents the state of currently loaded
-shared objects (of the traced application). If this information gets combined
-with the lttng-ust-dl(3) instrumentation, all aspects of dynamic loading that
-are relevant for symbol and linenumber-lookup are traced by LTTng.
+"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"
 
@@ -404,8 +437,8 @@ 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.
+.IP "LTTNG_UST_WITH_EXPERIMENTAL_BADDR_STATEDUMP"
+Experimentally allow liblttng-ust to perform a base-address statedump on session-enable.
 .PP
 
 .SH "SEE ALSO"