Help regarding -enable-openMP

graph-tool
1

Hi
I asked earlier as to how utilize the parallel processing in my code. Now I
installed it using the precompiled packages for Ubuntu. does that mean I'll
have to reinstall it from source using the openmp option in the configure
command?
Shubham

attachment.html (447 Bytes)

2

Hi

I asked earlier as to how utilize the parallel processing in my
code. Now I installed it using the precompiled packages for
Ubuntu. does that mean I'll have to reinstall it from source using the
openmp option in the configure command? Shubham

No, the ubuntu packages were already compiled with openmp enabled. You can
always verify if openmp was enabled or not by calling the show_config()
function. You should get something like this on Ubuntu:

    >>> graph_tool.show_config()
    version: 2.2.31 (commit 245d1e2c, Thu Mar 27 11:28:39 2014 +0100)
    gcc version: 4.8.2
    compilation flags: -D_FORTIFY_SOURCE=2 -I/usr/include/python2.7 -I/usr/include -I/usr/lib/python2.7/dist-packages/numpy/core/include/numpy -I/usr/lib/python2.7/dist-packages/scipy -I/usr/include -DSPARSEHASH_PREFIX=google -Wall -Wextra -Wno-unused-local-typedefs -Wno-unused-parameter -O3 -std=gnu++11 -ftemplate-depth-250 -Wno-deprecated -Wno-unknown-pragmas -O3 -fvisibility=default -fvisibility-inlines-hidden -fopenmp -I/usr/include -DSPARSEHASH_PREFIX=google -Wl,-Bsymbolic-functions -Wl,-z,relro -L/usr/lib -lpython2.7
    install prefix: /usr
    python dir: /usr/lib/python2.7/dist-packages
    graph filtering: True
    openmp: True
    uname: Linux sputnik 3.13.0-24-generic #46-Ubuntu SMP Thu Apr 10 19:11:08 UTC 2014 x86_64

The 'openmp: True' line above indicates openmp was enabled during compilation.

Best,
Tiago

3

Hi, I already installed graph_tool from precompiled packages for ubuntu and
I'm running dfs_search into a random graph generated earlier. This indicates
that I'm running dfs_search with openmp enabled already? I would like to run
without openmp just to compare times. It's possible?

thanks!

4

Hi, I already installed graph_tool from precompiled packages for ubuntu and
I'm running dfs_search into a random graph generated earlier. This indicates
that I'm running dfs_search with openmp enabled already?

Yes.

I would like to run without openmp just to compare times. It's
possible?

You can set the number of threads at run-time to 1, by calling
graph_tool.openmp_set_num_threads(1). This effectively turns off openmp.

But note that not all algorithms are parallelizable. DFS search, for
instance, cannot be written in parallel, since the vertices must be
followed in a specific order.

Best,
Tiago