Thanks for the help. Yah, running the example again using core binding, I get similar results to Junchao as well: 1 core: 2808 ms 2 core: 1398 ms 4 core: 989 ms 8 core: 1083 ms
On Fri, Sep 8, 2023 at 4:39 PM Junchao Zhang <[email protected]> wrote: > Hi, Chris, > this is my result of running your test on a local machine (8 cores, 16 > hardware threads). I use OpenMPI with command line like > mpirun --bind-to core -n <np> ./main > np=1 Solve duration: 2132 > np=2 Solve duration: 1116 > np=4 Solve duration: 990 > np=8 Solve duration: 1257 > > Note when I used > $ mpirun -n 4 ./main > Solve duration: 22693 > > It suggests binding is important. > > --Junchao Zhang > > > On Fri, Sep 8, 2023 at 4:53 PM Barry Smith <[email protected]> wrote: > >> >> For the size problem you are running this is very unexpected. The >> reductions should only start to dominate for thousands of MPI ranks, not 2. >> >> First thing I recommend is to run the streams benchmark. Then check the >> binding that MPI is doing for the two processes. You want to bind to cores >> in different NUMA regions. It could be that it is binding both processes to >> cores that share the same cache. The MatSolve should be embarressingly >> parallel but you are getting almost no speed up in it, so something very >> "wrong" is happening. >> >> >> >> Event Count Time (sec) Flop >> --- Global --- --- Stage ---- Total >> Max Ratio Max Ratio Max Ratio Mess AvgLen >> Reduct %T %F %M %L %R %T %F %M %L %R Mflop/s >> >> VecDot 182 1.0 1.9998e-01 1.0 2.26e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 7 5 0 0 0 7 5 0 0 0 1129 >> VecDotNorm2 91 1.0 6.6214e-02 1.0 2.26e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 2 5 0 0 0 2 5 0 0 0 3409 >> VecNorm 92 1.0 1.4790e-01 1.0 1.14e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 5 3 0 0 0 5 3 0 0 0 771 >> >> VecDot 198 1.0 2.1037e+00 1.1 1.23e+08 1.0 0.0e+00 0.0e+00 >> 2.0e+02 33 5 0 0 43 33 5 0 0 45 117 >> VecDotNorm2 99 1.0 5.0169e-01 1.2 1.23e+08 1.0 0.0e+00 0.0e+00 >> 9.9e+01 7 5 0 0 22 7 5 0 0 22 489 >> VecNorm 100 1.0 1.3131e+00 1.0 6.20e+07 1.0 0.0e+00 0.0e+00 >> 1.0e+02 21 3 0 0 22 21 3 0 0 23 94 >> VecScatterEnd 198 1.0 7.6160e-01 1.7 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 10 0 0 0 0 10 0 0 0 0 0 >> >> MatSolve 183 1.0 1.0882e+00 1.0 1.43e+09 1.0 0.0e+00 0.0e+00 >> 0.0e+00 40 35 0 0 0 40 35 0 0 0 1318 >> MatSolve 199 1.0 8.9666e-01 1.2 7.75e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 13 35 0 0 0 13 35 0 0 0 1729 >> >> >> On Sep 8, 2023, at 5:22 PM, Chris Hewson <[email protected]> wrote: >> >> Thanks for the quick response. >> >> The links to the log view files are below: >> 2 ranks: >> >> https://drive.google.com/file/d/1PGRsiHypWtN5h3uxdJBKy9WzEkE0mUgO/view?usp=drive_link >> >> 1 rank: >> >> https://drive.google.com/file/d/1hB2XyoNtLMHseZUT7jCuiixTQeBi_tjJ/view?usp=drive_link >> >> I'll also attach them to this email: >> **************************** 1 RANK ****************************** >> ------------------------------------------------------------------ PETSc >> Performance Summary: >> ------------------------------------------------------------------ >> >> ./petsc-testing on a named ubuntu-office with 1 processor, by chewson >> Fri Sep 8 15:16:51 2023 >> Using Petsc Release Version 3.19.5, unknown >> >> Max Max/Min Avg Total >> Time (sec): 2.746e+00 1.000 2.746e+00 >> Objects: 2.100e+01 1.000 2.100e+01 >> Flops: 4.117e+09 1.000 4.117e+09 4.117e+09 >> Flops/sec: 1.499e+09 1.000 1.499e+09 1.499e+09 >> MPI Msg Count: 0.000e+00 0.000 0.000e+00 0.000e+00 >> MPI Msg Len (bytes): 0.000e+00 0.000 0.000e+00 0.000e+00 >> MPI Reductions: 0.000e+00 0.000 >> >> Flop counting convention: 1 flop = 1 real number operation of type >> (multiply/divide/add/subtract) >> e.g., VecAXPY() for real vectors of length N >> --> 2N flops >> and VecAXPY() for complex vectors of length N >> --> 8N flops >> >> Summary of Stages: ----- Time ------ ----- Flop ------ --- Messages >> --- -- Message Lengths -- -- Reductions -- >> Avg %Total Avg %Total Count >> %Total Avg %Total Count %Total >> 0: Main Stage: 2.7458e+00 100.0% 4.1167e+09 100.0% 0.000e+00 >> 0.0% 0.000e+00 0.0% 0.000e+00 0.0% >> >> >> ------------------------------------------------------------------------------------------------------------------------ >> See the 'Profiling' chapter of the users' manual for details on >> interpreting output. >> Phase summary info: >> Count: number of times phase was executed >> Time and Flop: Max - maximum over all processors >> Ratio - ratio of maximum to minimum over all processors >> Mess: number of messages sent >> AvgLen: average message length (bytes) >> Reduct: number of global reductions >> Global: entire computation >> Stage: stages of a computation. Set stages with PetscLogStagePush() >> and PetscLogStagePop(). >> %T - percent time in this phase %F - percent flop in this >> phase >> %M - percent messages in this phase %L - percent message >> lengths in this phase >> %R - percent reductions in this phase >> Total Mflop/s: 10e-6 * (sum of flop over all processors)/(max time >> over all processors) >> >> ------------------------------------------------------------------------------------------------------------------------ >> Event Count Time (sec) Flop >> --- Global --- --- Stage ---- Total >> Max Ratio Max Ratio Max Ratio Mess AvgLen >> Reduct %T %F %M %L %R %T %F %M %L %R Mflop/s >> >> ------------------------------------------------------------------------------------------------------------------------ >> >> --- Event Stage 0: Main Stage >> >> MatMult 182 1.0 8.0351e-01 1.0 1.43e+09 1.0 0.0e+00 0.0e+00 >> 0.0e+00 29 35 0 0 0 29 35 0 0 0 1775 >> MatSolve 183 1.0 1.0882e+00 1.0 1.43e+09 1.0 0.0e+00 0.0e+00 >> 0.0e+00 40 35 0 0 0 40 35 0 0 0 1318 >> MatLUFactorNum 1 1.0 1.3892e-02 1.0 1.30e+07 1.0 0.0e+00 0.0e+00 >> 0.0e+00 1 0 0 0 0 1 0 0 0 0 934 >> MatILUFactorSym 1 1.0 2.1567e-02 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 1 0 0 0 0 1 0 0 0 0 0 >> MatAssemblyBegin 1 1.0 1.0420e-06 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> MatAssemblyEnd 1 1.0 6.9049e-03 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> MatGetRowIJ 1 1.0 3.8500e-07 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> MatGetOrdering 1 1.0 1.7026e-03 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> MatLoad 1 1.0 6.6749e-02 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 2 0 0 0 0 2 0 0 0 0 0 >> VecDot 182 1.0 1.9998e-01 1.0 2.26e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 7 5 0 0 0 7 5 0 0 0 1129 >> VecDotNorm2 91 1.0 6.6214e-02 1.0 2.26e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 2 5 0 0 0 2 5 0 0 0 3409 >> VecNorm 92 1.0 1.4790e-01 1.0 1.14e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 5 3 0 0 0 5 3 0 0 0 771 >> VecCopy 2 1.0 6.8473e-04 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> VecSet 3 1.0 1.3256e-03 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> VecAXPBYCZ 182 1.0 1.6542e-01 1.0 4.51e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 6 11 0 0 0 6 11 0 0 0 2729 >> VecWAXPY 182 1.0 1.4476e-01 1.0 2.26e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 5 5 0 0 0 5 5 0 0 0 1559 >> VecLoad 2 1.0 1.0104e-02 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> KSPSetUp 1 1.0 9.9204e-03 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> KSPSolve 1 1.0 2.6210e+00 1.0 4.10e+09 1.0 0.0e+00 0.0e+00 >> 0.0e+00 95 100 0 0 0 95 100 0 0 0 1566 >> PCSetUp 1 1.0 3.7232e-02 1.0 1.30e+07 1.0 0.0e+00 0.0e+00 >> 0.0e+00 1 0 0 0 0 1 0 0 0 0 349 >> PCApply 183 1.0 1.0885e+00 1.0 1.43e+09 1.0 0.0e+00 0.0e+00 >> 0.0e+00 40 35 0 0 0 40 35 0 0 0 1318 >> >> --- Event Stage 1: Unknown >> >> >> ------------------------------------------------------------------------------------------------------------------------ >> >> Object Type Creations Destructions. Reports information only >> for process 0. >> >> --- Event Stage 0: Main Stage >> >> Viewer 4 1 >> Matrix 3 1 >> Vector 9 1 >> Krylov Solver 1 0 >> Preconditioner 1 0 >> Index Set 3 0 >> >> --- Event Stage 1: Unknown >> >> >> ======================================================================================================================== >> Average time to get PetscTime(): 1.51e-08 >> #PETSc Option Table entries: >> -log_view # (source: command line) >> #End of PETSc Option Table entries >> Compiled without FORTRAN kernels >> Compiled with full precision matrices (default) >> sizeof(short) 2 sizeof(int) 4 sizeof(long) 8 sizeof(void*) 8 >> sizeof(PetscScalar) 8 sizeof(PetscInt) 4 >> Configure options: --with-debugging=0 --prefix=/opt/anl/petsc-3.19.5 >> --download-mumps --download-scalapack --with-mpi=1 >> --with-mpi-dir=/opt/anl/mpich COPTFLAGS=-O2 CXXOPTFLAGS=-O2 FOPTFLAGS=-O2 >> ----------------------------------------- >> Libraries compiled on 2023-09-08 16:27:49 on ubuntu-office >> Machine characteristics: Linux-6.2.0-26-generic-x86_64-with-glibc2.35 >> Using PETSc directory: /opt/anl/petsc-3.19.5 >> Using PETSc arch: >> ----------------------------------------- >> >> Using C compiler: /opt/anl/mpich/bin/mpicc -fPIC -Wall -Wwrite-strings >> -Wno-unknown-pragmas -Wno-lto-type-mismatch -Wno-stringop-overflow >> -fstack-protector -fvisibility=hidden -O2 >> Using Fortran compiler: /opt/anl/mpich/bin/mpif90 -fPIC -Wall >> -ffree-line-length-none -ffree-line-length-0 -Wno-lto-type-mismatch >> -Wno-unused-dummy-argument -O2 >> ----------------------------------------- >> >> Using include paths: -I/opt/anl/petsc-3.19.5/include >> -I/opt/anl/mpich/include >> ----------------------------------------- >> >> Using C linker: /opt/anl/mpich/bin/mpicc >> Using Fortran linker: /opt/anl/mpich/bin/mpif90 >> Using libraries: -Wl,-rpath,/opt/anl/petsc-3.19.5/lib >> -L/opt/anl/petsc-3.19.5/lib -lpetsc -Wl,-rpath,/opt/anl/petsc-3.19.5/lib >> -L/opt/anl/petsc-3.19.5/lib -Wl,-rpath,/opt/anl/mpich/lib >> -L/opt/anl/mpich/lib -Wl,-rpath,/usr/lib/gcc/x86_64-linux-gnu/11 >> -L/usr/lib/gcc/x86_64-linux-gnu/11 -ldmumps -lmumps_common -lpord -lpthread >> -lscalapack -llapack -lblas -lm -lX11 -lmpifort -lmpi -lgfortran -lm >> -lgfortran -lm -lgcc_s -lquadmath -lstdc++ -lquadmath >> ----------------------------------------- >> >> ************************* 2 RANKS ************************************ >> ------------------------------------------------------------------ PETSc >> Performance Summary: >> ------------------------------------------------------------------ >> >> ./petsc-testing on a named ubuntu-office with 2 processors, by chewson >> Fri Sep 8 15:16:43 2023 >> Using Petsc Release Version 3.19.5, unknown >> >> Max Max/Min Avg Total >> Time (sec): 6.167e+00 1.001 6.164e+00 >> Objects: 3.200e+01 1.000 3.200e+01 >> Flops: 2.233e+09 1.000 2.233e+09 4.467e+09 >> Flops/sec: 3.625e+08 1.001 3.623e+08 7.247e+08 >> MPI Msg Count: 2.050e+02 1.000 2.050e+02 4.100e+02 >> MPI Msg Len (bytes): 3.437e+07 1.000 1.676e+05 6.874e+07 >> MPI Reductions: 4.580e+02 1.000 >> >> Flop counting convention: 1 flop = 1 real number operation of type >> (multiply/divide/add/subtract) >> e.g., VecAXPY() for real vectors of length N >> --> 2N flops >> and VecAXPY() for complex vectors of length N >> --> 8N flops >> >> Summary of Stages: ----- Time ------ ----- Flop ------ --- Messages >> --- -- Message Lengths -- -- Reductions -- >> Avg %Total Avg %Total Count >> %Total Avg %Total Count %Total >> 0: Main Stage: 6.1642e+00 100.0% 4.4670e+09 100.0% 4.100e+02 >> 100.0% 1.676e+05 100.0% 4.400e+02 96.1% >> >> >> ------------------------------------------------------------------------------------------------------------------------ >> See the 'Profiling' chapter of the users' manual for details on >> interpreting output. >> Phase summary info: >> Count: number of times phase was executed >> Time and Flop: Max - maximum over all processors >> Ratio - ratio of maximum to minimum over all processors >> Mess: number of messages sent >> AvgLen: average message length (bytes) >> Reduct: number of global reductions >> Global: entire computation >> Stage: stages of a computation. Set stages with PetscLogStagePush() >> and PetscLogStagePop(). >> %T - percent time in this phase %F - percent flop in this >> phase >> %M - percent messages in this phase %L - percent message >> lengths in this phase >> %R - percent reductions in this phase >> Total Mflop/s: 10e-6 * (sum of flop over all processors)/(max time >> over all processors) >> >> ------------------------------------------------------------------------------------------------------------------------ >> Event Count Time (sec) Flop >> --- Global --- --- Stage ---- Total >> Max Ratio Max Ratio Max Ratio Mess AvgLen >> Reduct %T %F %M %L %R %T %F %M %L %R Mflop/s >> >> ------------------------------------------------------------------------------------------------------------------------ >> >> --- Event Stage 0: Main Stage >> >> BuildTwoSided 1 1.0 3.1824e-05 1.0 0.00e+00 0.0 2.0e+00 4.0e+00 >> 1.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> MatMult 198 1.0 1.3480e+00 1.4 7.76e+08 1.0 4.0e+02 9.4e+04 >> 0.0e+00 19 35 97 54 0 19 35 97 54 0 1151 >> MatSolve 199 1.0 8.9666e-01 1.2 7.75e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 13 35 0 0 0 13 35 0 0 0 1729 >> MatLUFactorNum 1 1.0 7.1852e-03 1.0 6.43e+06 1.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 1789 >> MatILUFactorSym 1 1.0 1.0472e-02 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> MatAssemblyBegin 1 1.0 9.8700e-07 1.4 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> MatAssemblyEnd 1 1.0 6.8341e-03 1.1 0.00e+00 0.0 4.0e+00 2.3e+04 >> 5.0e+00 0 0 1 0 1 0 0 1 0 1 0 >> MatGetRowIJ 1 1.0 1.9930e-06 6.3 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> MatGetOrdering 1 1.0 7.4472e-04 1.1 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> MatLoad 1 1.0 9.8562e-02 1.0 0.00e+00 0.0 1.0e+01 2.7e+06 >> 1.7e+01 2 0 2 39 4 2 0 2 39 4 0 >> VecDot 198 1.0 2.1037e+00 1.1 1.23e+08 1.0 0.0e+00 0.0e+00 >> 2.0e+02 33 5 0 0 43 33 5 0 0 45 117 >> VecDotNorm2 99 1.0 5.0169e-01 1.2 1.23e+08 1.0 0.0e+00 0.0e+00 >> 9.9e+01 7 5 0 0 22 7 5 0 0 22 489 >> VecNorm 100 1.0 1.3131e+00 1.0 6.20e+07 1.0 0.0e+00 0.0e+00 >> 1.0e+02 21 3 0 0 22 21 3 0 0 23 94 >> VecCopy 2 1.0 7.4971e-04 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> VecSet 202 1.0 8.0035e-02 1.5 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 1 0 0 0 0 1 0 0 0 0 0 >> VecAXPBYCZ 198 1.0 1.2889e-01 1.5 2.46e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 2 11 0 0 0 2 11 0 0 0 3811 >> VecWAXPY 198 1.0 9.1526e-02 1.0 1.23e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 1 5 0 0 0 1 5 0 0 0 2683 >> VecLoad 2 1.0 9.8983e-03 1.0 0.00e+00 0.0 4.0e+00 1.2e+06 >> 1.6e+01 0 0 1 7 3 0 0 1 7 4 0 >> VecScatterBegin 198 1.0 1.2941e-03 1.0 0.00e+00 0.0 4.0e+02 9.4e+04 >> 0.0e+00 0 0 97 54 0 0 0 97 54 0 0 >> VecScatterEnd 198 1.0 7.6160e-01 1.7 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 10 0 0 0 0 10 0 0 0 0 0 >> SFSetGraph 1 1.0 7.6630e-05 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> SFSetUp 1 1.0 1.2410e-04 1.0 0.00e+00 0.0 4.0e+00 2.3e+04 >> 1.0e+00 0 0 1 0 0 0 0 1 0 0 0 >> SFPack 198 1.0 5.1814e-05 1.3 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> SFUnpack 198 1.0 3.8273e-05 1.3 0.00e+00 0.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> KSPSetUp 2 1.0 4.7077e-03 1.1 0.00e+00 0.0 0.0e+00 0.0e+00 >> 2.0e+00 0 0 0 0 0 0 0 0 0 0 0 >> KSPSolve 1 1.0 6.0344e+00 1.0 2.23e+09 1.0 4.0e+02 9.4e+04 >> 4.0e+02 98 100 97 54 87 98 100 97 54 90 738 >> PCSetUp 2 1.0 1.8496e-02 1.0 6.43e+06 1.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 695 >> PCSetUpOnBlocks 1 1.0 1.8435e-02 1.0 6.43e+06 1.0 0.0e+00 0.0e+00 >> 0.0e+00 0 0 0 0 0 0 0 0 0 0 697 >> PCApply 199 1.0 9.5103e-01 1.1 7.75e+08 1.0 0.0e+00 0.0e+00 >> 0.0e+00 15 35 0 0 0 15 35 0 0 0 1630 >> >> --- Event Stage 1: Unknown >> >> >> ------------------------------------------------------------------------------------------------------------------------ >> >> Object Type Creations Destructions. Reports information only >> for process 0. >> >> --- Event Stage 0: Main Stage >> >> Viewer 4 1 >> Matrix 5 1 >> Vector 13 2 >> Index Set 5 2 >> Star Forest Graph 1 0 >> Krylov Solver 2 0 >> Preconditioner 2 0 >> >> --- Event Stage 1: Unknown >> >> >> ======================================================================================================================== >> Average time to get PetscTime(): 2.47e-08 >> Average time for MPI_Barrier(): 4.406e-07 >> Average time for zero size MPI_Send(): 4.769e-06 >> #PETSc Option Table entries: >> -log_view # (source: command line) >> #End of PETSc Option Table entries >> Compiled without FORTRAN kernels >> Compiled with full precision matrices (default) >> sizeof(short) 2 sizeof(int) 4 sizeof(long) 8 sizeof(void*) 8 >> sizeof(PetscScalar) 8 sizeof(PetscInt) 4 >> Configure options: --with-debugging=0 --prefix=/opt/anl/petsc-3.19.5 >> --download-mumps --download-scalapack --with-mpi=1 >> --with-mpi-dir=/opt/anl/mpich COPTFLAGS=-O2 CXXOPTFLAGS=-O2 FOPTFLAGS=-O2 >> ----------------------------------------- >> Libraries compiled on 2023-09-08 16:27:49 on ubuntu-office >> Machine characteristics: Linux-6.2.0-26-generic-x86_64-with-glibc2.35 >> Using PETSc directory: /opt/anl/petsc-3.19.5 >> Using PETSc arch: >> ----------------------------------------- >> >> Using C compiler: /opt/anl/mpich/bin/mpicc -fPIC -Wall -Wwrite-strings >> -Wno-unknown-pragmas -Wno-lto-type-mismatch -Wno-stringop-overflow >> -fstack-protector -fvisibility=hidden -O2 >> Using Fortran compiler: /opt/anl/mpich/bin/mpif90 -fPIC -Wall >> -ffree-line-length-none -ffree-line-length-0 -Wno-lto-type-mismatch >> -Wno-unused-dummy-argument -O2 >> ----------------------------------------- >> >> Using include paths: -I/opt/anl/petsc-3.19.5/include >> -I/opt/anl/mpich/include >> ----------------------------------------- >> >> Using C linker: /opt/anl/mpich/bin/mpicc >> Using Fortran linker: /opt/anl/mpich/bin/mpif90 >> Using libraries: -Wl,-rpath,/opt/anl/petsc-3.19.5/lib >> -L/opt/anl/petsc-3.19.5/lib -lpetsc -Wl,-rpath,/opt/anl/petsc-3.19.5/lib >> -L/opt/anl/petsc-3.19.5/lib -Wl,-rpath,/opt/anl/mpich/lib >> -L/opt/anl/mpich/lib -Wl,-rpath,/usr/lib/gcc/x86_64-linux-gnu/11 >> -L/usr/lib/gcc/x86_64-linux-gnu/11 -ldmumps -lmumps_common -lpord -lpthread >> -lscalapack -llapack -lblas -lm -lX11 -lmpifort -lmpi -lgfortran -lm >> -lgfortran -lm -lgcc_s -lquadmath -lstdc++ -lquadmath >> ----------------------------------------- >> >> Chris >> >> >> On Fri, Sep 8, 2023 at 3:00 PM Barry Smith <[email protected]> wrote: >> >>> >>> It would be very helpful if you could run on 1 and 2 ranks with >>> -log_view and send all the output. >>> >>> >>> >>> On Sep 8, 2023, at 4:52 PM, Chris Hewson <[email protected]> wrote: >>> >>> Hi There, >>> >>> I am trying to solve a linear problem and am having an issue when I use >>> more MPI processes with the KSPsolve slowing down considerably the more >>> processes I add. >>> >>> The matrix itself is 620100 X 620100 with ~5 million non-zero entries, I >>> am using petsc version 3.19.5 and have tried with a couple different >>> versions of mpich getting the same behavior (v4.1.2 w/ device ch4:ofi and >>> v3.3.2 w/ ch3:sock). >>> >>> In testing, I've noticed the following trend for speed for the KSPSolve >>> function call: >>> 1 core: 4042 ms >>> 2 core: 7085 ms >>> 4 core: 26573 ms >>> 8 core: 65745 ms >>> 16 core: 149283 ms >>> >>> This was all done on a single node machine w/ 16 non-hyperthreaded >>> cores. We solve quite a few different matrices with PETSc using MPI and >>> haven't noticed an impact like this on performance before. >>> >>> I am very confused by this and am a little stumped at the moment as to >>> why this was happening. I've been using the KSPBCGS solver to solve the >>> problem. I have tried with multiple different solvers and pre-conditioners >>> (we usually don't use a pre-conditioner for this part of our code). >>> >>> It did seem that using the piped BCGS solver did help improve the >>> parallel speed slightly (maybe 15%), but it still doesn't come close to the >>> single threaded speed. >>> >>> I'll attach a link to a folder that contains the specific A, x and b >>> matrices for this problem, as well as a main.cpp file that I was using for >>> testing. >>> >>> >>> https://drive.google.com/drive/folders/1CEDinKxu8ZbKpLtwmqKqP1ZIDG7JvDI1?usp=sharing >>> >>> I was testing this in our main code base, but don't include that here, >>> and observe very similar speed results to the ones above. We do use Metis >>> to graph partition in our own code and checked the vector and matrix >>> partitioning and that all made sense. I could be doing the partitioning >>> incorrectly in the example (not 100% sure how it works with the viewer/load >>> functions). >>> >>> Any insight or thoughts on this would be greatly appreciated. >>> >>> Thanks, >>> >>> *Chris Hewson* >>> Senior Reservoir Simulation Engineer >>> ResFrac >>> +1.587.575.9792 >>> >>> >>> >>
