Dear List, I have a hybrid MPI/Pthreads program named "my_hybrid_app", this program is memory-intensive and take advantage of multi-threading to improve memory throughput. I run "my_hybrid_app" on two machines, which have same hardware configuration but different OS and GCC. The problem is: when I run "my_hybrid_app" with one process, two machines behaves the same: the more number of threads, the better the performance; however, when I run "my_hybrid_app" with two or more processes. The first machine still increase performance with more threads, the second machine degrades in performance with more threads.
Since running "my_hybrid_app" with one process behaves correctly, I suspect my linking to MPI library has some problem. Would somebody point me in the right direction? Thanks in advance. Attached are the commandline used, my machine informantion and link informantion. p.s. 1: Commandline single process: ./my_hybrid_app <number of threads> multiple process: mpirun -np 2 ./my_hybrid_app <number of threads> p.s. 2: Machine Informantion The first machine is CentOS 5.3 with GCC 4.1.2: Target: x86_64-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=x86_64-redhat-linux Thread model: posix gcc version 4.1.2 20080704 (Red Hat 4.1.2-44) The second machine is SUSE Enterprise Server 11 with GCC 4.3.4: Target: x86_64-suse-linux Configured with: ../configure --prefix=/usr --infodir=/usr/share/info --mandir=/usr/share/man --libdir=/usr/lib64 --libexecdir=/usr/lib64 --enable-languages=c,c++,objc,fortran,obj-c++,java,ada --enable-checking=release --with-gxx-include-dir=/usr/include/c++/4.3 --enable-ssp --disable-libssp --with-bugurl=http://bugs.opensuse.org/--with-pkgversion='SUSE Linux' --disable-libgcj --disable-libmudflap --with-slibdir=/lib64 --with-system-zlib --enable-__cxa_atexit --enable-libstdcxx-allocator=new --disable-libstdcxx-pch --enable-version-specific-runtime-libs --program-suffix=-4.3 --enable-linux-futex --without-system-libunwind --with-cpu=generic --build=x86_64-suse-linux Thread model: posix gcc version 4.3.4 [gcc-4_3-branch revision 152973] (SUSE Linux) p.s. 3: ldd Informantion The first machine: $ ldd my_hybrid_app libm.so.6 => /lib64/libm.so.6 (0x000000358d400000) libmpi.so.0 => /usr/local/openmpi/lib/libmpi.so.0 (0x00002af0d53a7000) libopen-rte.so.0 => /usr/local/openmpi/lib/libopen-rte.so.0 (0x00002af0d564a000) libopen-pal.so.0 => /usr/local/openmpi/lib/libopen-pal.so.0 (0x00002af0d5895000) libdl.so.2 => /lib64/libdl.so.2 (0x000000358d000000) libnsl.so.1 => /lib64/libnsl.so.1 (0x000000358f000000) libutil.so.1 => /lib64/libutil.so.1 (0x000000359a600000) libgomp.so.1 => /usr/lib64/libgomp.so.1 (0x00002af0d5b07000) libpthread.so.0 => /lib64/libpthread.so.0 (0x000000358d800000) libc.so.6 => /lib64/libc.so.6 (0x000000358cc00000) /lib64/ld-linux-x86-64.so.2 (0x000000358c800000) librt.so.1 => /lib64/librt.so.1 (0x000000358dc00000) The second machine: $ ldd my_hybrid_app linux-vdso.so.1 => (0x00007fff3eb5f000) libmpi.so.0 => /root/opt/openmpi/lib/libmpi.so.0 (0x00007f68627a1000) libm.so.6 => /lib64/libm.so.6 (0x00007f686254b000) libopen-rte.so.0 => /root/opt/openmpi/lib/libopen-rte.so.0 (0x00007f68622fc000) libopen-pal.so.0 => /root/opt/openmpi/lib/libopen-pal.so.0 (0x00007f68620a5000) libdl.so.2 => /lib64/libdl.so.2 (0x00007f6861ea1000) libnsl.so.1 => /lib64/libnsl.so.1 (0x00007f6861c89000) libutil.so.1 => /lib64/libutil.so.1 (0x00007f6861a86000) libgomp.so.1 => /usr/lib64/libgomp.so.1 (0x00007f686187d000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f6861660000) libc.so.6 => /lib64/libc.so.6 (0x00007f6861302000) /lib64/ld-linux-x86-64.so.2 (0x00007f6862a58000) librt.so.1 => /lib64/librt.so.1 (0x00007f68610f9000) I installed openmpi-1.4.2 to a user directory /root/opt/openmpi and use "-L/root/opt/openmpi -Wl,-rpath,/root/opt/openmpi" when linking. -- Huiwei Lv PhD. student at Institute of Computing Technology, Beijing, China http://asg.ict.ac.cn/lhw
