[GRASS-dev] Re: [GRASS GIS] #657: add --with-openmp support to ./configure

[GRASS GIS]

#657: add --with-openmp support to ./configure
------------------------+---------------------------------------------------
  Reporter:  hamish     |       Owner:  grass-dev at lists.osgeo.org
      Type:  task       |      Status:  new                      
  Priority:  normal     |   Milestone:  7.0.0                    
 Component:  Compiling  |     Version:  svn-trunk                
Resolution:             |    Keywords:  openmp                   
  Platform:  All        |         Cpu:  All                      
------------------------+---------------------------------------------------
Comment (by huhabla):

 OpenMP support is implemented in the gpde and the gmath libraries. In the
 gmath lib many linear equation solver and all blas level 2 and 3 functions
 are parallelized with OpenMP.

 OpenMP flags are compiler dependent, thus OpenMP support should be set
 using C- and linker-flags bevor configure.
 I.e: for gcc > 4.2:
 {{{
 CFLAGS="-O3 -Wall -Werror-implicit-function-declaration -fno-common
 -fopenmp"
 LDFLAGS="-lgomp"
 }}}

 This should enable OpenMP support in the libraries and ALL depending
 modules.

 You can test the OpenMP support when compiling the gpde and gmath tests by
 hand (switch into the test directories in the lib dirs and type make). The
 test library modules "test.gmath.lib" and "test.gpde.lib" should be
 available in the path after starting grass.

 The gmath lib test module "test.gmath.lib" provides additionally
 benchmarks for blas level 2 and 3 functions and for many solver.

 {{{
 gmath/test> test.gmath.lib help

 Description:
  Performs benchmarks, unit and integration tests for the gmath library

 Usage:
  test.gmath.lib [-uia] [unit=string] [integration=string] [rows=value]
    [solverbench=string] [blasbench=string] [--verbose] [--quiet]

 Flags:
   -u   Run all unit tests
   -i   Run all integration tests
   -a   Run all unit and integration tests
  --v   Verbose module output
  --q   Quiet module output

 Parameters:
          unit   Choose the unit tests to run
                 options: blas1,blas2,blas3,solver,ccmath,matconv
   integration   Choose the integration tests to run
                 options:
          rows   The size of the matrices and vectors for benchmarking
                 default: 1000
   solverbench   Choose solver benchmark
                 options: krylov,direct
     blasbench   Choose blas benchmark
                 options: blas2,blas3

 }}}

 I.e testing the speedup of the blas level 2 and 3 functions of the latest
 svn trunk of grass7, compiled with the flags mentioned above on a 8 core
 intel xeon system:

 {{{
 gmath/test> setenv OMP_NUM_THREADS 1
 gmath/test> test.gmath.lib blasbench=blas2 rows=5000

 ++ Running blas level 2 benchmark ++
 Computation time G_math_Ax_sparse: 0.244123
 Computation time G_math_Ax_sband: 0.280636
 Computation time G_math_d_Ax: 0.134494
 Computation time G_math_d_Ax_by: 0.18556
 Computation time G_math_d_x_dyad: 0.268684

 -- gmath lib tests finished successfully --

 gmath/test> setenv OMP_NUM_THREADS 4
 gmath/test> test.gmath.lib blasbench=blas2 rows=5000

 ++ Running blas level 2 benchmark ++
 Computation time G_math_Ax_sparse: 0.072549
 Computation time G_math_Ax_sband: 0.192712
 Computation time G_math_d_Ax: 0.036652
 Computation time G_math_d_Ax_by: 0.047904
 Computation time G_math_d_x_dyad: 0.080534

 -- gmath lib tests finished successfully --

 gmath/test> setenv OMP_NUM_THREADS 1
 gmath/test> test.gmath.lib blasbench=blas3 rows=1000

 ++ Running blas level 3 benchmark ++
 Computation time G_math_d_aA_B: 0.013263
 ^[[AComputation time G_math_d_AB: 18.729

 -- gmath lib tests finished successfully --

 gmath/test> setenv OMP_NUM_THREADS 4
 gmath/test> test.gmath.lib blasbench=blas3 rows=1000

 ++ Running blas level 3 benchmark ++
 Computation time G_math_d_aA_B: 0.006946
 Computation time G_math_d_AB: 4.80446

 -- gmath lib tests finished successfully --

 }}}

 The gmath library should work fine with OpenMP support. In the gpde
 library is still a bug (race condition) in the linear equation system
 creator.

-- 
Ticket URL: <http://trac.osgeo.org/grass/ticket/657#comment:4>
GRASS GIS <http://grass.osgeo.org>