X-Git-Url: http://git.lttng.org/?p=lttng-ust.git;a=blobdiff_plain;f=README;h=78160a30f8210e0cdb9e8e6e8483aa3a6204e117;hp=23b831978a748d7acc1cd63e16c11ad7c9082714;hb=29865d1ccafc065d07e0de67b196790ed36ab396;hpb=628e1d81fe575cfd281d8e0758b672b23d890c09 diff --git a/README b/README index 23b83197..78160a30 100644 --- a/README +++ b/README @@ -67,7 +67,11 @@ USAGE: "TRACEPOINT_DEFINE" and include the tracepoint provider. - Use "-I." for the compilation unit containing the tracepoint provider include (e.g. tp.c). - - Link application with "-ldl -llttng-ust". + - Link application with "-ldl". + - 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". - Include the tracepoint provider header into all C files using the provider. - Example: @@ -86,15 +90,11 @@ USAGE: - 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. - Enable instrumentation and control tracing with the "lttng" command from lttng-tools. See lttng-tools doc/quickstart.txt. @@ -113,6 +113,10 @@ ENVIRONMENT VARIABLES: recommended for applications with time constraints on the process startup time. + - The compilation flag "-DLTTNG_UST_DEBUG_VALGRIND" should be enabled + at build time to allow liblttng-ust to be used with valgrind + (side-effect: disables per-cpu buffering). + TRACE VIEWER: @@ -140,7 +144,7 @@ PACKAGE CONTENTS: - tests Various test programs - - liblttng-ust-libc + - liblttng-ust-libc-wrapper An example library that can be LD_PRELOAD'ed to instrument some calls to libc (currently malloc() and free()) in any program without need to recompile it.