X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=doc%2Fman%2Flttng-ust.3;h=7cc3bfde5b7112b354d6d5c4e81fc4c0115d45dc;hb=13fb2d2c14d49d2e5457df7b5f02e99e979464c3;hp=88025c0e702727da568f9a99b7dbb70bd248cc2c;hpb=0a7c55a5916a0ff52bca2dcbfe4ac825a3bb179d;p=lttng-ust.git

diff --git a/doc/man/lttng-ust.3 b/doc/man/lttng-ust.3
index 88025c0e..7cc3bfde 100644
--- a/doc/man/lttng-ust.3
+++ b/doc/man/lttng-ust.3
@@ -238,6 +238,10 @@ For instance, add within a function:
 As a call to the tracepoint. It will only be activated when requested by
 lttng(1) through lttng-sessiond(8).
 
+Even though LTTng-UST supports tracepoint() call site duplicates having
+the same provider and event name, it is recommended to use a
+provider event name pair only once within the source code to help
+mapping events back to their call sites when analyzing the trace.
 .fi
 
 .SH "BUILDING/LINKING THE TRACEPOINT PROVIDER"
@@ -257,11 +261,11 @@ carefully:
     - If building the provider directly into the application,
       link the application with "\-llttng-ust".
     - If building a static library for the provider, link the static
-      library with "\-lllttng-ust".
+      library with "\-llttng-ust".
     - Include the tracepoint provider header into all C files using
       the provider.
     - Example:
-        tests/hello/  hello.c tp.c ust_tests_hello.h Makefile.example
+      - tests/hello/  hello.c tp.c ust_tests_hello.h Makefile.example
 
   2) Compile the Tracepoint Provider separately from the application,
      using dynamic linking:
@@ -276,15 +280,15 @@ carefully:
     - Link application with "\-ldl".
     - Set a LD_PRELOAD environment to preload the tracepoint provider
       shared object before starting the application when tracing is
-      needed.
+      needed. Another way is to dlopen the tracepoint probe when needed
+      by the application.
     - Example:
       - tests/demo/   demo.c  tp*.c ust_tests_demo*.h demo-trace
 
-  - Note about dlopen() usage: due to locking side-effects due to the
-    way libc lazily resolves Thread-Local Storage (TLS) symbols when a
-    library is dlopen'd, linking the tracepoint probe or liblttng-ust
-    with dlopen() is discouraged. They should be linked with the
-    application using "\-llibname" or loaded with LD_PRELOAD.
+  - Note about dlclose() usage: it is not safe to use dlclose on a
+    provider shared object that is being actively used for tracing due
+    to a lack of reference counting from lttng-ust to the used shared
+    object.
   - Enable instrumentation and control tracing with the "lttng" command
     from lttng-tools. See lttng-tools doc/quickstart.txt.
   - Note for C++ support: although an application instrumented with
@@ -304,6 +308,38 @@ LD_PRELOAD=liblttng-ust-fork.so appname).
 
 .fi
 
+.SH "CONTEXT"
+
+.PP
+Context information can be prepended by the tracer before each, or some,
+events. The following context information is supported by LTTng-UST:
+.PP
+
+.PP
+.IP "vtid"
+Virtual thread ID: thread ID as seen from the point of view of the
+process namespace.
+.PP
+
+.PP
+.IP "vpid"
+Virtual process ID: process ID as seen from the point of view of the
+process namespace.
+.PP
+
+.PP
+.IP "procname"
+Thread name, as set by exec() or prctl(). It is recommended that
+programs set their thread name with prctl() before hitting the first
+tracepoint for that thread.
+.PP
+
+.PP
+.IP "pthread_id"
+Pthread identifier. Can be used on architectures where pthread_t maps
+nicely to an unsigned long type.
+.PP
+
 .SH "ENVIRONMENT VARIABLES"
 
 .PP