Hi Mehran, I'll try to correct you where I can.
On 21 January 2014 18:34, Mehran Khan <i...@mehrankhan.com> wrote: > Hello everyone, > I have been trying to instrument the Apache web server, the latest version > (2.4.7 from the URL http://httpd.apache.org/download.cgi#apache24) for LTTng > UST tracing > 1. To start with the simplest case, I created a *.tp file named > smallestTracePoint.tp with the content below > TRACEPOINT_EVENT( > mk, > apache_process_entry, > TP_ARGS(), > TP_FIELDS() > ) This is good. > 2. Then I ran the following > lttng-gen-tp smallestTracePoint.tp -o smallestTracePoint.h -o > smallestTracePoint.c > > which generated the files smallestTracePoint.c and smallestTracePoint.h You can just say $ lttng-gen-tp smallestTracePoint.tp and it will generate the .h and .c. > 3. Then, I put the smallestTracePoint.h and smallestTracePoint.c in > httpd-2.4.7/server directory, > included smallestTracePoint.h in the main.c file and added trace points in > the int main(int argc, const char * const argv[]) and *init_process(int > *argc, const char * const * *argv) functions. That's good. > 4. Then I added -finstrument-functions in the configure file (Line number > 2830) in the extracted httpd-2.4.7 directory, full line below > ac_compile='$CC -c $CFLAGS -finstrument-functions $CPPFLAGS > conftest.$ac_ext >&5' As Suchakra said, -finstrument-functions is not related. You can use it later if you want, but let's leave it out for now. Also, if you want to add compilation flags like this, pass them at configure time. Also, _never_ change generated files (such as the configure script of Makefiles). They are way too complicated for a human and will get overwritten anyway. Instead, you should modify the configure.in or Makefile.in files, in this case. To add a compilation flag, you could do: $ ./configure CFLAGS="-finstrument-function" > 5. Then, from the /httpd-2.4.7 directory, I ran the following command to > configure the installation, it completed without any error. > ./configure --libdir=/usr/lib/usr/lib/liblttng-ust.so > --with-included-apr This is wrong. --libdir is used to tell autotools in which directory to install the compiled libraries. ./configure --with-included-apr is sufficient. > 6. When I ran the command 'make', I get the following error after a while > ... > make[1]: Entering directory `/root/httpd-2.4.7' > /root/httpd-2.4.7/srclib/apr/libtool --silent --mode=compile gcc -std=gnu99 > -g -O2 -pthread -DLINUX -D_REENTRANT -D_GNU_SOURCE -I. > -I/root/httpd-2.4.7/os/unix -I/root/httpd-2.4.7/include > -I/root/httpd-2.4.7/srclib/apr/include > -I/root/httpd-2.4.7/srclib/apr-util/include > -I/root/httpd-2.4.7/srclib/apr-util/xml/expat/lib > -I/root/httpd-2.4.7/modules/aaa -I/root/httpd-2.4.7/modules/cache > -I/root/httpd-2.4.7/modules/core -I/root/httpd-2.4.7/modules/database > -I/root/httpd-2.4.7/modules/filters -I/root/httpd-2.4.7/modules/ldap > -I/root/httpd-2.4.7/modules/loggers -I/root/httpd-2.4.7/modules/lua > -I/root/httpd-2.4.7/modules/proxy -I/root/httpd-2.4.7/modules/session > -I/root/httpd-2.4.7/modules/ssl -I/root/httpd-2.4.7/modules/test > -I/root/httpd-2.4.7/server -I/root/httpd-2.4.7/modules/arch/unix > -I/root/httpd-2.4.7/modules/dav/main -I/root/httpd-2.4.7/modules/generators > -I/root/httpd-2.4.7/modules/mappers -prefer-non-pic -static -c modules.c && > touch modules.lo > gcc -std=gnu99 -g -O2 -pthread -DLINUX -D_REENTRANT -D_GNU_SOURCE > -I. -I/root/httpd-2.4.7/os/unix -I/root/httpd-2.4.7/include > -I/root/httpd-2.4.7/srclib/apr/include > -I/root/httpd-2.4.7/srclib/apr-util/include > -I/root/httpd-2.4.7/srclib/apr-util/xml/expat/lib > -I/root/httpd-2.4.7/modules/aaa -I/root/httpd-2.4.7/modules/cache > -I/root/httpd-2.4.7/modules/core -I/root/httpd-2.4.7/modules/database > -I/root/httpd-2.4.7/modules/filters -I/root/httpd-2.4.7/modules/ldap > -I/root/httpd-2.4.7/modules/loggers -I/root/httpd-2.4.7/modules/lua > -I/root/httpd-2.4.7/modules/proxy -I/root/httpd-2.4.7/modules/session > -I/root/httpd-2.4.7/modules/ssl -I/root/httpd-2.4.7/modules/test > -I/root/httpd-2.4.7/server -I/root/httpd-2.4.7/modules/arch/unix > -I/root/httpd-2.4.7/modules/dav/main -I/root/httpd-2.4.7/modules/generators > -I/root/httpd-2.4.7/modules/mappers -c /root/httpd-2.4.7/server/buildmark.c > /root/httpd-2.4.7/srclib/apr/libtool --silent --mode=link gcc -std=gnu99 -g > -O2 -pthread -o httpd modules.lo buildmark.o -export-dynamic > server/libmain.la modules/core/libmod_so.la modules/http/libmod_http.la > server/mpm/event/libevent.la os/unix/libos.la -L/usr/lib/x86_64-linux-gnu > -lpcre /root/httpd-2.4.7/srclib/apr-util/libaprutil-1.la > /root/httpd-2.4.7/srclib/apr-util/xml/expat/libexpat.la > /root/httpd-2.4.7/srclib/apr/libapr-1.la -luuid -lrt -lcrypt -lpthread -ldl > server/.libs/libmain.a(main.o): In function `main': > /root/httpd-2.4.7/server/main.c:443: undefined reference to > `__tracepoint_mk___apache_process_entry' > server/.libs/libmain.a(main.o): In function `init_process': > /root/httpd-2.4.7/server/main.c:284: undefined reference to > `__tracepoint_mk___apache_process_entry' > server/.libs/libmain.a(main.o): In function > `__tracepoint_cb_mk___apache_process_entry': > /root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to > `tracepoint_dlopen' > /root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to > `__tracepoint_mk___apache_process_entry' > /root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to > `tracepoint_dlopen' > /root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to > `tracepoint_dlopen' > /root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to > `tracepoint_dlopen' > /root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to > `__tracepoint_mk___apache_process_entry' > /root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to > `tracepoint_dlopen' > /root/httpd-2.4.7/server/smallestTracePoint.h:13: undefined reference to > `tracepoint_dlopen' > collect2: ld returned 1 exit status > make[1]: *** [httpd] Error 1 > make[1]: Leaving directory `/root/httpd-2.4.7' > make: *** [all-recursive] Error 1 > > I have tried including the smallestTracePoint.c file in the local makefile > (/root/httpd-2.4.7/MakeFile)... didn't do me any good. > Any idea what I am doing wrong ? That's right, you have to compile the .c file somewhere. I suggest you check where main.c is mentionned in a Makefile.in, and add smallestTracePoint.c there. Don't forget to re-run configure, and try to make again. This should get rid of the undefined references to __tracepoint_mk___apache_process_entry. For the other undefined references, it is because your tracepoint requires additional libraries, libdl and liblttng-ust. You should then add "-ldl -llttng-ust" to where the final executable is linked. When inspecting the build log, we see that this is done by the top-level Makefile, so we will go edit the top-level Makefile.in. (there might be a better place to put -ldl -llttng-ust, but it will do for now) Apache should now build with the tracepoint included. Then, doing $ lttng create $ lttng enable-event -u -a $ lttng start $ ./httpd (httpd complains about missing config file, but hits the tracepoint anyway) $ lttng stop $ lttng view ... [08:30:18.522789766] (+0.000173646) simark apache:apache_process_entry: { cpu_id = 2 }, { } ... Yay ! I made a commit here to show the modifications I made to make it work: https://github.com/simark/httpd/commit/2c6d73c47156350233b346e9eaa49ffb07a58e6e Hopefully this can help you get started. Iif you instrument apache in an interesting/useful way, feel free to share your work, it could be useful for others! Simon > > LTTng version on the instance: 2.4.0-rc2 - Époque Opaque > > Linux Distribution: Ubuntu 12.04.3 LTS > > > Thanks, > > > -- > Mehran > > > _______________________________________________ > lttng-dev mailing list > lttng-dev@lists.lttng.org > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev > _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
