CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 08/17/2017 01:00 PM, Michael Bieri wrote:
> Hi again,
>
> Thanks Sebastian for your answer.
>
> I finally managed to make it work. I'll describe what I did and I also
> have some questions about it:
>
> - The cgal_create_cmake_script and cgal_create_CMakeLists do not create
> any TBB-related code, at all, never. Is that correct?
Yes.

> - So I had to merge the TBB-related stuff from your above linked
> CMakeLists into the CMakeLists of my project.
>
> - Compiling TBB is easy, BUT it does not offer any installation routine.
> So I had to specify all TBB_* variables in my project with ccmake or
> -D... manually. Or does CGAL/TBB offer anything to automatically detect
> those variables?

TBBROOT should be sufficient as documented here:
http://doc.cgal.org/latest/Manual/installation.html#title57

> - Once it compiled, the meshing will run with a reasonable number of
> threads right away. Or should I configure something manually?

This is handled by the default task scheduler created by TBB.
Look at TBB's doc for more info.

Sebastien.


> Best regards,
> Michael
>
> On Thu, Aug 17, 2017 at 9:02 AM, Sebastien Loriot (GeometryFactory)
> <
>  
> <mailto:>>
>  wrote:
>
>     On 08/16/2017 12:17 PM, Michael Bieri wrote:
>
>         Hi all
>
>         The CGAL documentation just says that I have to enable the
>         parallel tag,
>         like:
>
>         typedef CGAL::Parallel_tag Concurrency_tag;
>         typedef
>         
> CGAL::Mesh_triangulation_3<Mesh_domain,CGAL::Default,Concurrency_tag>::type
>         Tr;
>
>         Surprisingly, it compiled right after that modification, even
>         though I
>         neither set any link flags for the Intel TBB nor did I find any
>         traces
>         that I already have Intel TBB on my system (Mac Book Pro) at all.
>
>
>     If you copy-paste a cmake script from CGAL it might be automatically
>     done. I know this a proposal to issue a warning when the user ask
>     for parallel support while it is not available but it was not
>     implemented IIRC. One way to check is to verify that
>     CGAL_LINKED_WITH_TBB is defined.
>     Otherwise have a look at this cmake script for example:
>     
> https://github.com/CGAL/cgal/blob/master/Mesh_3/examples/Mesh_3/CMakeLists.txt
>     
> <https://github.com/CGAL/cgal/blob/master/Mesh_3/examples/Mesh_3/CMakeLists.txt>
>
>         What exactly do I need to do to use parallel meshing? How can I
>         control
>         the number of threads? Is there an example?
>
>
>     You should refer to the Intel TBB documentation.
>     Something like this should work:
>
>     {
>       tbb::task_scheduler_init tsi(6); // 6 threads
>       run_parallel_algo1(); // Uses 6 threads
>     }
>
>     Sebastien.
>
>
>         Thanks a lot and best regards,
>         Michael
>
>
>
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