Hi again,
as Jed noted, adding --with-threadcomm to configure finally gives you
the OpenMP parallelization (--with-pthreadclasses also gives you pthread
parallelization, but this may not be available on your Windows machine).
With this I get the following execution times on my laptop for e.g.
VecScale() for n=m=500:
Single-threaded: 9.3448e-01 sec
OpenMP: 4.8728e-01 sec
PThreads: 4.3991e-01 sec
This factor of two is fairly common for VecScale() and indicates a
saturation of the memory bus. Other operations may saturate later.
Best regards,
Karli
On 11/05/2013 01:26 AM, Danyang Su wrote:
Hi All,
I have test the same example under Ubuntu12.04 X64. The PETSc-dev
version is update to date (GIT Date: 2013-11-01 14:59:20 -0500) and the
installation is smooth without any error. The speedup of MPI version is
linear scalable but the speedup of OpenMP version does not change. *From
the CPU usage, the program still run in one thread when use OpenMP. *
The commands to run the test are as follows:
openmp
./ex2f -threadcomm_type openmp -threadcomm_nthreads 4 -m 1000 -n 1000
-log_summary log_ex2f_1000x1000_ubuntu1204_omp_p4.log
mpi
mpiexec -n 4 ./ex2f -m 1000 -n 1000 -log_summary
log_ex2f_1000x1000_ubuntu1204_mpi_p4.log
This problem is so tricky to me. Can anybody confirm if KSP solver is
parallelized for OpenMP version?
Thanks and regards,
Danyang
On 31/10/2013 4:54 PM, Danyang Su wrote:
Hi All,
I have a question on the speedup of PETSc when using OpenMP. I can get
good speedup when using MPI, but no speedup when using OpenMP.
The example is ex2f with m=100 and n=100. The number of available
processors is 16 (32 threads) and the OS is Windows Server 2012. The
log files for 4 and 8 processors are attached.
The commands I used to run with 4 processors are as follows:
Run using MPI
mpiexec -n 4 Petsc-windows-ex2f.exe -m 100 -n 100 -log_summary
log_100x100_mpi_p4.log
Run using OpenMP
Petsc-windows-ex2f.exe -threadcomm_type openmp -threadcomm_nthreads 4
-m 100 -n 100 -log_summary log_100x100_openmp_p4.log
The PETSc used for this test is PETSc for Windows
http://www.mic-tc.ch/downloads/PETScForWindows.zip, but I guess this
is not the problem because the same problem exists when I use
PETSc-dev in Cygwin. I don't know if this problem exists in Linux,
would anybody help to test?
Thanks and regards,
Danyang
