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Using Tikki with Gnu OpenMP runtime

Last edited by Philippe Virouleau

The GNU OpenMP runtime, libGOMP, does not support the OMPT API yet. Therefore to use Tikki for a program compiled with GCC you will need to execute it with an OMPT-ready runtime.

Thankfully the LLVM OpenMP runtime has a compatibility layer with the GNU OpenMP runtime. By default installing the LLVM runtime will also install symbolic links from libgomp.so to libomp.so, but depending on the version of GCC the library may be named libgomp.so.1, in which case you will need to setup a symbolic link yourself to libomp.so.

Then you will just need to make sure your LD_LIBRARY_PATH is appropriately set to detect this symbolic link before the original libGOMP library.

For instance here is what happens when I compile the hello-task.c example:

$ /usr/bin/gcc -o test-task -fopenmp test/hello-task.c -lm   
$ ldd test-task 
	linux-vdso.so.1 (0x00007fff6a3f8000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f9c945c8000)
	libgomp.so.1 => /usr/lib/x86_64-linux-gnu/libgomp.so.1 (0x00007f9c9439b000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f9c9417e000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f9c93ddf000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f9c94acf000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f9c93bdb000)
$ LD_LIBRARY_PATH=$HOME/install/libkomp-hashmaps/lib:$LD_LIBRARY_PATH ldd test-task 
	linux-vdso.so.1 (0x00007fff35dac000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f84bd589000)
	libgomp.so.1 => /home/openmp/install/llvm-openmp/lib/libgomp.so.1 (0x00007f84bd2bf000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f84bd0a2000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f84bcd03000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f84bda90000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f84bcaff000)
$ ls $HOME/install/llvm-openmp/lib -al
total 1052
drwxr-xr-x 2 openmp openmp   4096 Sep 11 16:10 .
drwxr-xr-x 4 openmp openmp   4096 Jun  3 16:57 ..
lrwxrwxrwx 1 openmp openmp      9 Sep 11 16:10 libgomp.so -> libomp.so
lrwxrwxrwx 1 openmp openmp      9 Aug  6 11:15 libgomp.so.1 -> libomp.so
lrwxrwxrwx 1 openmp openmp      9 Sep 11 16:10 libiomp5.so -> libomp.so
-rw-r--r-- 1 openmp openmp 988280 Sep 11 16:05 libomp.so
-rw-r--r-- 1 openmp openmp  75728 Sep 11 16:10 libomptarget.so

Running your application with the appropriate LD_LIBRARY_PATH will let it use the LLVM runtime and will enable you to load the Tikki tool, as described here.

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