I've configured and built gpreftools. however, I can't seem to find the generated profile file of my program to display it.
I took the following actions:
Adding the -lprofiler linker flag to my .pro, building the program and the flag is added correctly at the linking stage.
QMAKE_LFLAGS += -lprofiler
Running with:
$ CPUPROFILE=/tmp/prof.out /path/to/executable
Executing:
$ pprof --gv /path/to/MyExe /tmp/prof.out
Then I get the following:
Failed to get profile: curl -s --max-time 90 'http:///pprof/profile?seconds=30' > /home/eslam/pprof/.tmp.MyExe.1509005857.: No such file or directory.
Anyone has a resolve on this?
Check that your program actually links to libprofiler.so. Some OSes (e.g. AFAIK some versions of ubuntu) do not actually add .so if none of it's symbols are actually used. E.g. ldd ./yourprogram should list libprofiler.so. If this does not happen, then you should prepend something like -Wl,--no-as-needed to your linker flags.
LD_PRELOAD method without rebuild
Besides passing -Wl,--no-as-needed,-lprofiler,--as-needed at build time mentioned by Eslam, you can also get it to work without modifying the build by passing the LD_PRELOAD option at runtime as:
LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libprofiler.so CPUPROFILE=prof.out ./main.out
You can find libprofiler.so easily with locate libprofiler.so.
See also: How can I profile C++ code running on Linux?
Tested in Ubuntu 18.04.
Related
Main question:
In Ubuntu trying to debug an embedded application running in QNX, I am getting the following error message from gdb:
warning: Shared object "$SOLIB_PATH/libc.so.4" could not be validated and will be ignored.,
Q: What is the "validation" operation going on ?
After some research I found that the information reported by readelf -n libfoo.so contains a build-id and that this is compared against something and there could be a mismatch causing gdb to refuse to load the library. If that's the case what ELF file's build-id is the shared object's build-id compared against ? Can I find this information parsing the executable file ?
More context:
I have a .core file for this executable. I am using a version of gdb provided by QNX and making sure I use set sysroot and set solib-search-path to where I installed the QNX toolchain.
My full command to launch gdb in Ubuntu is :
$QNX_TOOLCHAIN_PATH/ntox86_64-gdb --init-eval-command 'set sysroot $SYSROOT_PATH' --init-eval-command 'set solib-search-path $SOLIB_PATH --init-eval-command 'python sys.path.append("/usr/share/gcc-8/python");' -c path-to-exe.core path-to-executable-bin
Gdb is complaining that it cannot load shared objects :
warning: Shared object "$SOLIB_PATH/libc.so.4" could not be validated and will be ignored.
The big thing here is to make sure you're using the exact same binary that is on the target (that the program runs over). This is often quite difficult with libc, especially because libc/ldqnx are sometimes "the same thing" and it confuses gdb.
The easiest way to do this is to log your mkifs output (on the linux host):
make 2>&1 | tee build-out.txt
and read through that, search for libc.so.4, and copy the binary that's being pulled onto the target into . (wherever you're running gdb) so you don't need to mess with SOLIB paths (the lazy solution).
Alternatively, scp/ftp a new libc (one that you want to use, and ideally one that you have associated symbols for) into /tmp and use LD_LIBRARY_PATH to pull that one (and DL_DEBUG=libs to confirm, if you need). Use that same libc to debug
source: I work at QNX and even we struggle with gdb + libc sometimes
I have found several conflicting answers over this topic. This blog post requires libuwind, but that doesn't work on Mac OS X. I included #include <google/profiler.h> in my code, however my compiler (g++) could not find the library. I installed gperftools via homebrew. In addition, I found this stackoverflow question showing this:
Then I ran pprof to generate the output:
[hidden ~]$ pprof --text ./a.out cpu.profile
Using local file ./a.out.
Using local file cpu.profile.
Removing __sigtramp from all stack traces.
Total: 282 samples
107 37.9% 37.9% 107 37.9% 0x000000010d72229e
16 5.7% 43.6% 16 5.7% 0x000000010d721a5f
12 4.3% 47.9% 12 4.3% 0x000000010d721de8
...
Running that command (without any of the prior steps) gets me this:
[hidden]$ pprof --text ./a.out cpu.profile
Using remote profile at ./a.out.
Failed to get the number of symbols from http://cpu.profile/pprof/symbol
Why does it try to access an internet site on my machine and a local file on his/hers?
Attempting to link lib profiler as a dry run with g++ gets me:
[hidden]$ g++ -l libprofiler
ld: library not found for -llibprofiler
clang: error: linker command failed with exit code 1 (use -v to see invocation)
I have looked at the man pages, the help option text, the official online guide, blog posts, and many other sources.
I am so confused right now. Can someone help me use gperftools?
The result of my conversation with #osgx was this script. I tried to clean it up a bit. It likely contains quite a few unnecessary options too.
The blog post https://dudefrommangalore.wordpress.com/2012/02/09/profiling-c-code-using-google-performance-tools/ "Profiling C++ code using Google Performance Tools" 2012 by dudefrommangalore missed the essential step.
You should link your program (which you want to be profiled) with cpu profiler library of gperftools library.
Check official manual: http://goog-perftools.sourceforge.net/doc/cpu_profiler.html, part "Linking in the Library"
add -lprofiler to the link-time step for your executable. (It's also probably possible to add in the profiler at run-time using LD_PRELOAD, but this isn't necessarily recommended.)
Second step is to collect the profile, run the code with profiling enabled. In linux world it was done by setting controlling environment variable CPUPROFILE before running:
CPUPROFILE=name_of_profile ./program_to_be_profiled
Third step is to use pprof (google-pprof in ubuntu world). Check that there is not-empty name_of_profile profile file generated; it there is no such file, pprof will try to do remote profile fetch (you see output of such try).
pprof ./program_to_be_profiled name_of_profile
First you need to run your program with profiling enabled.
This is usually first linking your program with libprofiler and then running it with CPUPROFILE=cpu.profile.
I.e.
$ CPUPROFILE=cpu.profile my_program
I think that later step is what you have been missing.
The program will create this cpu.profile file when it exits. And then you can use pprof (preferably from github.com/google/pprof) on it to visualize/analyze.
I am having trouble compiling Fortran code with references to DISLIN. I have downloaded DISLIN from the website, unzipped the file and ran the setup. I have added an environment variable called DISLIN (C:\dislin) and added C:\dislin\win to the PATH section of my system variables.
I am trying to compile some example code of the DISLIN website which includes line
USE DISLIN
I am using a MinGW shell to compile with command gfortran -o progrname -ldislin EX11_1.f90 and am getting the following error:
Fatal Error: Cant open module file 'dislin.mod' for reading at (1): No such file or directory.
I have tried changing the variable path and even moving the dislin.mod file (which is there) but still get the same message.
Ok I fixed this problem so thought I come back and post what worked for me incase any one else needs it...
Install both DISLIN and MinGW on the c drive
Copy disgf.a from /c/dislin and dislin.f90 from /c/dislin/gf into the directory containing your fortran files
(for me this is /c/MinGW/pnote)
Using the MinGW shell navigate to you files: cd /c/MinGW/pnote
compile dislin.f90 and your fortran program: gfortran -c dislin.f90 progName.f90 (dislin.f90 obviously only needs to be done once)
link libraries etc and compile: gfortran progName.o disgf.a -luser32 -lgdi32 -lopengl32 -o exeName
'run' exeName
You probably need to specify the path to the DISLIN module files:
gfortran EX11_1.f90 -o progrname -ldislin -I/path/to/DISLIN/modules
and, if not already configured like described here, also the path to the library itself:
gfortran EX11_1.f90 -o progrname -ldislin -I/path/to/DISLIN/modules \
-L/path/to/DISLIN/library
They provide a batch file (windows) to do the compiling and linking for you.
f90link -c My_Program
This is located in c:\dislin\Win
Also, if you are having trouble with the dislin.mod file which resides in c:\dislin\gf then recompile that with the -c compile option. I found all of this info in c:\dislin\readme.inf
near as I can tell (Jan 2018) dislin (64 bit) fails miserably with gfortran 7.2, period; and probably with many other newer compilers.
When trying to link, gfortran 7 says 'dislin.mod' is an unrecognizable format.
I think this program is highly dependent on exactly correct version synchronization - something that renders such software useless imho after many years in research.
and no, the correctness of various 'paths' seems not to help.
after all, gnuplot works, "at all". Not sure why I spent so much time on brand x.
jrc
I'm trying to debug a CUDA program, but when I'm launching gdb like so:
$ gdb -i=mi <program name>
$ r <program arguments>
I'm getting:
/home/wvxvw/Projects/cuda/exercise-1-udacity/cs344/HW2/hw:
error while loading shared libraries: libcudart.so.5.0:
cannot open shared object file: No such file or directory
Process gdb-inferior killed
(formatted for readability)
(I'm running gdb using M-xgdb) If that matters, then CUDA libraries are in the .bashrc
export PATH="/usr/local/cuda/bin:$PATH"
export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:/usr/local/cuda/lib64"
error while loading shared libraries: libcudart.so.5.0
This error has nothing to do with GDB: your executable, when run from inside GDB, can't find the library it needs.
export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:/usr/local/cuda/lib64"
GDB runs your program in a new $SHELL, so that should have worked. I wonder if there is some interaction with emacs.
In any case, this:
(gdb) set env LD_LIBRARY_PATH /usr/local/cuda/lib64
(gdb) run
should fix this problem.
Update:
as I've mentioned it before, ld path is set properly
No, it isn't. If it was, you wouldn't have the problem.
Now, I don't know why it isn't set properly. If you really want to find out, start by running GDB outside emacs (to exclude possible emacs interactions).
If the problem is still present, gdb show env, shell env, adding echo "Here" to your ~/.basrc, etc. should help you find where things are not working as you expect them.
I've had this problem as well. One way to look at it is that even if the LD_LIBRARY_PATH variable is correct when you enter show env into gdb, it may not be correct when you actually execute the program because gdb executes $SHELL -c <program> to run the program. Try this as a test, run $SHELL from the command line and then echo $LD_LIBRARY_PATH. Is it correct? If not, then you probably need to add it to your rc (.tcshrc in my case).
I had a similar problem when trying to run gdb on windows 7. I use MobaXterm to access a Linux toolbox. I installed gdb separately from http://www.gnu.org/software/gdb/ . I got it to work by making sure gdb could find the correct .dll files as mentioned by Employed Russian. If you have MobaXterm installed the .dll files should appear in your home directory in MobaXterm/slash/bin.
gdb however did not recognize the LD_LIBRARY_PATH variable. For me, it worked when I used the PATH variable instead:
(gdb) set env PATH C:\Users\Joshua\Documents\MobaXterm\slash\bin
(gdb) run
I would think using PATH instead of LD_LIBRARY_PATH might work for you provided you put the correct path to your library.
gdb is looking for a library, so why are you concerned with the include path? You may want to try to set the gdb option "solib-search-path" to point to the location of the libcudart.so.5.0 library.
I have two different version of a library let's say
libxyz.so
at two different location
1) /home/maverick/dev/libxyz.so ( development Version)
2) /home/maverick/prod/libxyz.so ( Production Version )
I have a setup that compile my program and link with appropriate version of the library depending on LD_LIBRARY_PATH. for example If I want to link my program with dev version of libxyz.so i change my LD_LIBRARY_PATH to add /home/maverick/dev and if I want to link with prod version I change LD_LIBRARY_PATH to add /home/maverick/prod instead.
I compiled my program by linking with dev version and the output of
ldd MyProg
is
libxyz.so => /home/maverick/dev/libxyz.so
If i run the program it loads the libxyz.so from
/home/maverick/dev/libxyz.so
and runs fine.
it this point my LD_LIBRARY_PATH includes /home/maverick/dev not /home/maverick/prod
but when I try to debug this program through GDB
gdb MyProg
it loads the libxyz.so from location
/home/maverick/prod/libxyz.so
I have trouble making GDB load the correct version of the library during debug. So till now what I am doing is first launch the program (that load the dev version) and attach gdb to that PID this way its works fine. but if it run like
gdb MyProg
it dosen't
I tried every thing to fix this like setting up sysroot, solib-search-path in GDB but nothing is working.
if fact when I set up sysroot to point to the debug version of the library gdb gave some message like
.dynamic section for XXX is not at the expected address
any suggestion would be appreciated.
I have trouble making GDB load the correct version of the library during debug.
Let me guess: you are using tcsh, right?
The problem most likely comes from yoour ~/.cshrc resetting LD_LIBRARY_PATH to /home/maverick/prod.
When you run the program in GDB, it executes $SHELL -c your-program [args...] (so as to allow you to use I/O redirection).
Solution: don't touch environment in your .cshrc for non-interactive shell, e.g. start it with:
if ($?prompt == 0) exit