On Sat, Feb 8, 2020 at 4:34 PM Zhang, Hong via petsc-dev < petsc-dev@mcs.anl.gov> wrote:
> I did some further investigation. The overhead persists for both the PETSc > shared library and the static library. In the previous example, it does not > call any PETSc function, the first CUDA function becomes very slow when it > is linked to the petsc so. This indicates that the slowdown occurs if the > symbol (cudafree)is searched through the petsc so, but does not occur if > the symbol is found directly in the cuda runtime lib. > > So the issue has nothing to do with the dynamic linker. The following > example can be used to easily reproduce the problem (cudaFree(0) always > takes ~7.5 seconds). > 1) This should go to OLCF admin as Jeff suggests 2) Just to make sure I understand, a static executable with this code is still slow on the cudaFree(), since CUDA is a shared library by default. I think we should try: a) Forcing a full static link, if possible b) Asking OLCF about link resolution order It sounds like a similar thing I have seen in the past where link resolution order can exponentially increase load time. Thanks, Matt > bash-4.2$ cat ex_simple_petsc.c > #include <time.h> > #include <cuda_runtime.h> > #include <stdio.h> > #include <petscmat.h> > > int main(int argc,char **args) > { > clock_t start,s1,s2,s3; > double cputime; > double *init,tmp[100] = {0}; > PetscErrorCode ierr=0; > > ierr = PetscInitialize(&argc,&args,(char*)0,NULL);if (ierr) return ierr; > start = clock(); > cudaFree(0); > s1 = clock(); > cudaMalloc((void **)&init,100*sizeof(double)); > s2 = clock(); > cudaMemcpy(init,tmp,100*sizeof(double),cudaMemcpyHostToDevice); > s3 = clock(); > printf("free time =%lf malloc time =%lf copy time =%lf\n",((double) (s1 > - start)) / CLOCKS_PER_SEC,((double) (s2 - s1)) / CLOCKS_PER_SEC,((double) > (s3 - s2)) / CLOCKS_PER_SEC); > ierr = PetscFinalize(); > return ierr; > } > > Hong > > On Feb 7, 2020, at 3:09 PM, Zhang, Hong <hongzh...@anl.gov> wrote: > > Note that the overhead was triggered by the first call to a CUDA function. > So it seems that the first CUDA function triggered loading petsc so (if > petsc so is linked), which is slow on the summit file system. > > Hong > > On Feb 7, 2020, at 2:54 PM, Zhang, Hong via petsc-dev < > petsc-dev@mcs.anl.gov> wrote: > > Linking any other shared library does not slow down the execution. The > PETSc shared library is the only one causing trouble. > > Here are the ldd output for two different versions. For the first version, > I removed -lpetsc and it ran very fast. The second (slow) version was > linked to petsc so. > > bash-4.2$ ldd ex_simple > linux-vdso64.so.1 => (0x0000200000050000) > liblapack.so.0 => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/liblapack.so.0 > (0x0000200000070000) > libblas.so.0 => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libblas.so.0 > (0x00002000009b0000) > libhdf5hl_fortran.so.100 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/hdf5-1.10.3-pgiul2yf4auv7krecd72t6vupd7e3qgn/lib/libhdf5hl_fortran.so.100 > (0x0000200000e80000) > libhdf5_fortran.so.100 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/hdf5-1.10.3-pgiul2yf4auv7krecd72t6vupd7e3qgn/lib/libhdf5_fortran.so.100 > (0x0000200000ed0000) > libhdf5_hl.so.100 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/hdf5-1.10.3-pgiul2yf4auv7krecd72t6vupd7e3qgn/lib/libhdf5_hl.so.100 > (0x0000200000f50000) > libhdf5.so.103 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/hdf5-1.10.3-pgiul2yf4auv7krecd72t6vupd7e3qgn/lib/libhdf5.so.103 > (0x0000200000fb0000) > libX11.so.6 => /usr/lib64/libX11.so.6 (0x00002000015e0000) > libcufft.so.10 => /sw/summit/cuda/10.1.168/lib64/libcufft.so.10 > (0x0000200001770000) > libcublas.so.10 => /sw/summit/cuda/10.1.168/lib64/libcublas.so.10 > (0x0000200009b00000) > libcudart.so.10.1 => > /sw/summit/cuda/10.1.168/lib64/libcudart.so.10.1 (0x000020000d950000) > libcusparse.so.10 => > /sw/summit/cuda/10.1.168/lib64/libcusparse.so.10 (0x000020000d9f0000) > libcusolver.so.10 => > /sw/summit/cuda/10.1.168/lib64/libcusolver.so.10 (0x0000200012f50000) > libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x000020001dc40000) > libdl.so.2 => /usr/lib64/libdl.so.2 (0x000020001ddd0000) > libpthread.so.0 => /usr/lib64/libpthread.so.0 (0x000020001de00000) > libmpiprofilesupport.so.3 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libmpiprofilesupport.so.3 > (0x000020001de40000) > libmpi_ibm_usempi.so => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libmpi_ibm_usempi.so > (0x000020001de70000) > libmpi_ibm_mpifh.so.3 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libmpi_ibm_mpifh.so.3 > (0x000020001dea0000) > libmpi_ibm.so.3 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libmpi_ibm.so.3 > (0x000020001df40000) > libpgf90rtl.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgf90rtl.so > (0x000020001e0b0000) > libpgf90.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgf90.so > (0x000020001e0f0000) > libpgf90_rpm1.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgf90_rpm1.so > (0x000020001e6a0000) > libpgf902.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgf902.so > (0x000020001e6d0000) > libpgftnrtl.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgftnrtl.so > (0x000020001e700000) > libatomic.so.1 => /usr/lib64/libatomic.so.1 (0x000020001e730000) > libpgkomp.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgkomp.so > (0x000020001e760000) > libomp.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libomp.so > (0x000020001e790000) > libomptarget.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libomptarget.so > (0x000020001e880000) > libpgmath.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgmath.so > (0x000020001e8b0000) > libpgc.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgc.so > (0x000020001e9d0000) > librt.so.1 => /usr/lib64/librt.so.1 (0x000020001eb40000) > libm.so.6 => /usr/lib64/libm.so.6 (0x000020001eb70000) > libgcc_s.so.1 => /usr/lib64/libgcc_s.so.1 (0x000020001ec60000) > libc.so.6 => /usr/lib64/libc.so.6 (0x000020001eca0000) > libz.so.1 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/zlib-1.2.11-2htm7ws4hgrthi5tyjnqxtjxgpfklxsc/lib/libz.so.1 > (0x000020001ee90000) > libxcb.so.1 => /usr/lib64/libxcb.so.1 (0x000020001eef0000) > /lib64/ld64.so.2 (0x0000200000000000) > libcublasLt.so.10 => > /sw/summit/cuda/10.1.168/lib64/libcublasLt.so.10 (0x000020001ef40000) > libutil.so.1 => /usr/lib64/libutil.so.1 (0x0000200020e50000) > libhwloc_ompi.so.15 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libhwloc_ompi.so.15 > (0x0000200020e80000) > libevent-2.1.so.6 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libevent-2.1.so.6 > (0x0000200020ef0000) > libevent_pthreads-2.1.so.6 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libevent_pthreads-2.1.so.6 > (0x0000200020f70000) > libopen-rte.so.3 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libopen-rte.so.3 > (0x0000200020fa0000) > libopen-pal.so.3 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libopen-pal.so.3 > (0x00002000210b0000) > libXau.so.6 => /usr/lib64/libXau.so.6 (0x00002000211a0000) > > > bash-4.2$ ldd ex_simple_slow > linux-vdso64.so.1 => (0x0000200000050000) > libpetsc.so.3.012 => > /autofs/nccs-svm1_home1/hongzh/Projects/petsc/arch-olcf-summit-sell-opt/lib/libpetsc.so.3.012 > (0x0000200000070000) > liblapack.so.0 => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/liblapack.so.0 > (0x0000200002be0000) > libblas.so.0 => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libblas.so.0 > (0x0000200003520000) > libhdf5hl_fortran.so.100 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/hdf5-1.10.3-pgiul2yf4auv7krecd72t6vupd7e3qgn/lib/libhdf5hl_fortran.so.100 > (0x00002000039f0000) > libhdf5_fortran.so.100 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/hdf5-1.10.3-pgiul2yf4auv7krecd72t6vupd7e3qgn/lib/libhdf5_fortran.so.100 > (0x0000200003a40000) > libhdf5_hl.so.100 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/hdf5-1.10.3-pgiul2yf4auv7krecd72t6vupd7e3qgn/lib/libhdf5_hl.so.100 > (0x0000200003ac0000) > libhdf5.so.103 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/hdf5-1.10.3-pgiul2yf4auv7krecd72t6vupd7e3qgn/lib/libhdf5.so.103 > (0x0000200003b20000) > libX11.so.6 => /usr/lib64/libX11.so.6 (0x0000200004150000) > libcufft.so.10 => /sw/summit/cuda/10.1.168/lib64/libcufft.so.10 > (0x00002000042e0000) > libcublas.so.10 => /sw/summit/cuda/10.1.168/lib64/libcublas.so.10 > (0x000020000c670000) > libcudart.so.10.1 => > /sw/summit/cuda/10.1.168/lib64/libcudart.so.10.1 (0x00002000104c0000) > libcusparse.so.10 => > /sw/summit/cuda/10.1.168/lib64/libcusparse.so.10 (0x0000200010560000) > libcusolver.so.10 => > /sw/summit/cuda/10.1.168/lib64/libcusolver.so.10 (0x0000200015ac0000) > libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00002000207b0000) > libdl.so.2 => /usr/lib64/libdl.so.2 (0x0000200020940000) > libpthread.so.0 => /usr/lib64/libpthread.so.0 (0x0000200020970000) > libmpiprofilesupport.so.3 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libmpiprofilesupport.so.3 > (0x00002000209b0000) > libmpi_ibm_usempi.so => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libmpi_ibm_usempi.so > (0x00002000209e0000) > libmpi_ibm_mpifh.so.3 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libmpi_ibm_mpifh.so.3 > (0x0000200020a10000) > libmpi_ibm.so.3 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libmpi_ibm.so.3 > (0x0000200020ab0000) > libpgf90rtl.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgf90rtl.so > (0x0000200020c20000) > libpgf90.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgf90.so > (0x0000200020c60000) > libpgf90_rpm1.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgf90_rpm1.so > (0x0000200021210000) > libpgf902.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgf902.so > (0x0000200021240000) > libpgftnrtl.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgftnrtl.so > (0x0000200021270000) > libatomic.so.1 => /usr/lib64/libatomic.so.1 (0x00002000212a0000) > libpgkomp.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgkomp.so > (0x00002000212d0000) > libomp.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libomp.so > (0x0000200021300000) > libomptarget.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libomptarget.so > (0x00002000213f0000) > libpgmath.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgmath.so > (0x0000200021420000) > libpgc.so => > /autofs/nccs-svm1_sw/summit/.swci/0-core/opt/spack/20180914/linux-rhel7-ppc64le/gcc-4.8.5/pgi-19.4-6acz4xyqjlpoaonjiiqjme2aknrfnzoy/linuxpower/19.4/lib/libpgc.so > (0x0000200021540000) > librt.so.1 => /usr/lib64/librt.so.1 (0x00002000216b0000) > libm.so.6 => /usr/lib64/libm.so.6 (0x00002000216e0000) > libgcc_s.so.1 => /usr/lib64/libgcc_s.so.1 (0x00002000217d0000) > libc.so.6 => /usr/lib64/libc.so.6 (0x0000200021810000) > libz.so.1 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/zlib-1.2.11-2htm7ws4hgrthi5tyjnqxtjxgpfklxsc/lib/libz.so.1 > (0x0000200021a10000) > libxcb.so.1 => /usr/lib64/libxcb.so.1 (0x0000200021a60000) > /lib64/ld64.so.2 (0x0000200000000000) > libcublasLt.so.10 => > /sw/summit/cuda/10.1.168/lib64/libcublasLt.so.10 (0x0000200021ab0000) > libutil.so.1 => /usr/lib64/libutil.so.1 (0x00002000239c0000) > libhwloc_ompi.so.15 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libhwloc_ompi.so.15 > (0x00002000239f0000) > libevent-2.1.so.6 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libevent-2.1.so.6 > (0x0000200023a60000) > libevent_pthreads-2.1.so.6 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libevent_pthreads-2.1.so.6 > (0x0000200023ae0000) > libopen-rte.so.3 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libopen-rte.so.3 > (0x0000200023b10000) > libopen-pal.so.3 => > /autofs/nccs-svm1_sw/summit/.swci/1-compute/opt/spack/20180914/linux-rhel7-ppc64le/pgi-19.4/spectrum-mpi-10.3.0.1-20190611-4ymaahbai7ehhw4rves5jjiwon2laz3a/lib/libopen-pal.so.3 > (0x0000200023c20000) > libXau.so.6 => /usr/lib64/libXau.so.6 (0x0000200023d10000) > > > On Feb 7, 2020, at 2:31 PM, Smith, Barry F. <bsm...@mcs.anl.gov> wrote: > > > ldd -o on the executable of both linkings of your code. > > My guess is that without PETSc it is linking the static version of the > needed libraries and with PETSc the shared. And, in typical fashion, the > shared libraries are off on some super slow file system so take a long time > to be loaded and linked in on demand. > > Still a performance bug in Summit. > > Barry > > > On Feb 7, 2020, at 12:23 PM, Zhang, Hong via petsc-dev < > petsc-dev@mcs.anl.gov> wrote: > > Hi all, > > Previously I have noticed that the first call to a CUDA function such as > cudaMalloc and cudaFree in PETSc takes a long time (7.5 seconds) on summit. > Then I prepared a simple example as attached to help OCLF reproduce the > problem. It turned out that the problem was caused by PETSc. The > 7.5-second overhead can be observed only when the PETSc lib is linked. If I > do not link PETSc, it runs normally. Does anyone have any idea why this > happens and how to fix it? > > Hong (Mr.) > > bash-4.2$ cat ex_simple.c > #include <time.h> > #include <cuda_runtime.h> > #include <stdio.h> > > int main(int argc,char **args) > { > clock_t start,s1,s2,s3; > double cputime; > double *init,tmp[100] = {0}; > > start = clock(); > cudaFree(0); > s1 = clock(); > cudaMalloc((void **)&init,100*sizeof(double)); > s2 = clock(); > cudaMemcpy(init,tmp,100*sizeof(double),cudaMemcpyHostToDevice); > s3 = clock(); > printf("free time =%lf malloc time =%lf copy time =%lf\n",((double) (s1 - > start)) / CLOCKS_PER_SEC,((double) (s2 - s1)) / CLOCKS_PER_SEC,((double) > (s3 - s2)) / CLOCKS_PER_SEC); > > return 0; > } > > > > > > > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>