[GRASS-dev] Compilation options

[Stefan Blumentrath]

Hei Anna,

Thanks for looking into this.

I did some tests with GRASS 7.2.1svn (r70188) and GRASS 7.3.svn (r70829) both compiled with --with-openmp

It seems that r.proj does not use multiple threads in GRASS 7.2 (not tested in 7.3. yet). v.surf.rst uses more cores in GRASS 7.2 with OpenMP but that does not bring down execution time at all. OpenMP seems to be disabled for v.surf.rst in GRASS 7.3. v.surf.bspline however, is significantly faster in GRASS 7.3 with OpenMP...

I will do some more, systematic tests and update the wiki entry as far as I can, if not someone with knowledge gets there first...

Cheers
Stefan

P.S.: Some preliminary test results:
# OpenMP support test
$ OMP_NUM_THREADS=10
$ export OMP_NUM_THREADS
$ time v.surf.rst input=points elevation=test  --o --qq

real    51m42.224s
user    398m2.766s
sys     0m18.874s

$ OMP_NUM_THREADS=1
$ export OMP_NUM_THREADS
$ time v.surf.rst input=points elevation=test  --o --qq

real    53m22.508s
user    53m10.607s
sys     0m4.793s

$ OMP_NUM_THREADS=10
$ export OMP_NUM_THREADS
$ time v.surf.bspline elevrand column=value output=elev_full --o
real    0m20.509s
user    3m11.412s
sys     0m1.963s

$ OMP_NUM_THREADS=1
$ export OMP_NUM_THREADS
$ time v.surf.bspline elevrand column=value output=elev_full --o
real    1m15.434s
user    1m14.738s
sys     0m0.447s

-----Original Message-----
From: Anna Petrášová [mailto:kratochanna at gmail.com] 
Sent: fredag 27. oktober 2017 17.00
To: Stefan Blumentrath <Stefan.Blumentrath at nina.no>
Cc: GRASS developers list (grass-dev at lists.osgeo.org) <grass-dev at lists.osgeo.org>
Subject: Re: [GRASS-dev] Compilation options

On Tue, Oct 24, 2017 at 10:27 AM, Stefan Blumentrath <Stefan.Blumentrath at nina.no> wrote:
> Hi again,
>
>
>
> Seek and ye shall find…
>
>
>
> So, there is:
>
> https://grasswiki.osgeo.org/wiki/OpenMP#OpenMP_support_in_GRASS_7 and
>
> https://grasswiki.osgeo.org/wiki/GPU
>
> Which helped me a bit further.
>
>
>
> However, my impression is that not all info there (esp. on OpenMP) is 
> up to date (e.g. latest development like here:
> https://lists.osgeo.org/pipermail/grass-dev/2017-August/085711.html).
> Neither did it became very clear to me which modules already have 
> robust and working support and which are just candidates or where 
> initial implementations are available (sometimes outside the code 
> base)…
>
>

I updated it slightly to reflect the new modules, as always, more work is needed on that page.
https://grasswiki.osgeo.org/wiki/OpenMP#OpenMP_support_in_GRASS_7

Anna

>
> Cheers
>
> Stefan
>
>
>
> From: grass-dev [mailto:grass-dev-bounces at lists.osgeo.org] On Behalf 
> Of Stefan Blumentrath
> Sent: mandag 23. oktober 2017 09.24
> To: GRASS developers list (grass-dev at lists.osgeo.org) 
> <grass-dev at lists.osgeo.org>
> Subject: [GRASS-dev] Compilation options
>
>
>
> Dear all,
>
>
>
> Does someone of you know which modules benefit from --with-openmp and 
> --with-opencl compilation options?
>
>
>
> I found this explanation of compilation options:
> https://grass.osgeo.org/grass72/source/snapshot/REQUIREMENTS.html
>
> But it does not cover OpenCL or OpenMP (as well as some few more other 
> option).
>
>
>
> If I wanted to find out myself, could I just search the code for 
> modules that import the relevant headers of the respective libraries?
>
> Or is that a bit more complex?
>
>
>
> Another question is if it would be recommended to use the different 
> options, as I understood e.g. using --with-pthread is not necessarily 
> a good choice…
>
>
>
> Thanks in advance.
>
>
>
> Cheers
>
> Stefan
>
>
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