From: compudj Date: Thu, 9 Mar 2006 23:33:39 +0000 (+0000) Subject: readme update X-Git-Tag: v0.12.20~1833 X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=c47538ac4c17d7627fb77de078235415a841a5c0;p=lttv.git readme update git-svn-id: http://ltt.polymtl.ca/svn@1656 04897980-b3bd-0310-b5e0-8ef037075253 --- diff --git a/ltt-usertrace/README b/ltt-usertrace/README index 4bdbf293..9e658d9e 100644 --- a/ltt-usertrace/README +++ b/ltt-usertrace/README @@ -28,14 +28,15 @@ gzip -cd ltt-usertrace-x.x.tar.gz | tar xvof - * Build the sample programs and install the headers and librairies into your system : su -cd /usr/src/usertrace-generic +cd /usr/src/ltt-usertrace make make install Feel free to look at the sample programs and the Makefile : they demonstrate very well the features of the usertrace package and how to use them. -* There are three ways to trace information from your application : +* There are three ways to trace information from your application. The choice + will principally depend on the trace data rate. 1) Easy way, but slow (printf style) See sample-printf.c for code example. @@ -84,15 +85,15 @@ user_generic.slow_printf: 35886.925685289 (/cpu_0), 15521, 7453, SYSCALL { "in: -2) The second way to log events is still easy, yet faster. It requires creating - your own XML description of your data structures. It will make it easier to - identify your data in the trace. Please read the comments in method 1) - explained previously, as they are not repeated here. - See sample.c for code example. +2) The second way to log events is still easy. The advantage is that it + will make it easier to identify your data in the trace viewer afterward. + Please read the comments in method 1) explained previously, as they + are not repeated here. + See sample.c and sample-thread-slow.c for code example. -- Go to the usertrace-generic directory +- Go to the ltt-usertrace directory su -cd /usr/src/usertrace-generic +cd /usr/src/ltt-usertrace - Create your own facility (i.e. user_myfacility.xml). See the ones available in /usr/share/LinuxTraceToolkitViewer/facilities for @@ -165,6 +166,50 @@ It will show, for example : user_myfacility.myevent: 39507.805584526 (/cpu_1), 15829, 15736, SYSCALL { "myapp.c", "main", 8, 1234, 0xf0f0f0f0 } +3) The third way to trace information from your application + +This method is cleary the _FASTEST_. It is principally I/O (disk and memory) +bound. It will create a companion process for each of you program's thread which +will dump the tracing information into /tmp/ltt-usertrace. + +See sample-highspeed.c and sample-thread-fast.c for code example. + +- Add the following statements to your program source (the define must come + _before_ the includes!) : + +#define LTT_TRACE +#define LTT_TRACE_FAST +#include + +- Add a call following the trace_user_myfacility_myevent function found in + /usr/include/ltt/ltt-facility-user_myfacility.h in your program. +For instance : +trace_user_myfacility_myevent(__FILE__, __func__, __LINE__, 1234, (void*)0xF0F0F0F0); + +- Compile your application with at least these parameters to gcc (it is splitted + on two lines, joined by a "\") : +gcc -lltt-usertrace-fast -I /usr/src/usertrace-generic -o myapp myapp.c \ + /usr/src/usertrace-generic/ltt-facility-loader-user_myfacility.c + +It requires a supplementary operation when you take the trace : +- Start tracing (with lttctl) +- Start your application +- Let your application run... +- Stop tracing +- Move or copy /tmp/ltt-usertrace info your trace. +i.e., if your trace is in /tmp/trace1 : +su +mv /tmp/ltt-usertrace /tmp/trace1 + + +Then, to see only the user_myfacility events : +lttv -m textDump -t /tmp/trace1 -e "event.facility=user_myfacility" + +It will show, for example : +user_myfacility.myevent: 39507.805584526 (/ltt-usertrace/process-26174.26174.39236180500380_0), 15829, 15736, USER_MODE { "myapp.c", "main", 8, 1234, 0xf0f0f0f0 } + + + * Fun feature : function instrumentation Here is how to generate a full trace of you program function calls. @@ -183,8 +228,8 @@ Then, to see only the function_entry and function_exit events : lttv -m textDump -t /tmp/trace1 -e "event.facility=user_generic & (event.name=function_entry & event.name=function_exit)" It will show, for example : -user_generic.function_entry: 59329.709939111 (/cpu_0), 19250, 18581, SYSCALL { 0x8048454, 0x80484c2 } -user_generic.function_exit: 59329.709944613 (/cpu_0), 19250, 18581, SYSCALL { 0x8048454, 0x80484c2 } +user_generic.function_entry: 59329.709939111 (/ltt-usertrace/process-26202.0.39949996866578_0), 19250, 18581, USER_MODE { 0x8048454, 0x80484c2 } +user_generic.function_exit: 59329.709944613 (/ltt-usertrace/process-26202.0.39949996866578_0), 19250, 18581, USER_MODE { 0x8048454, 0x80484c2 } you can then use (from the binutils package) addr2line -e sample-instrument-fct -i -f 0x8048454