[GRASS-dev] Week 11: GRASS GIS 3D flowlines

[Newcomb, Doug]

Anna,
This parallels my experience in running v.surf.rst with OpenMP enabled and
disabled on large areas.  With OpenMP enabled on an 8 core computer, the
process used 700% of CPU time, but took about twice as long as running the
same data set on a single core with OpenMP disabled.

Doug


On Wed, Aug 6, 2014 at 10:58 PM, Anna Petrášová <kratochanna at gmail.com>
wrote:

> Hi,
>
>
> On Tue, Aug 5, 2014 at 11:04 AM, Newcomb, Doug <doug_newcomb at fws.gov>
> wrote:
>
>> Anna,
>> Will you post the  benchmarking results  for the OpenMP computation vs
>> the non-OpenMP?
>>
>>
> after some testing, my conclusion is that OpenMP does not really speed up
> gradient computation and it can even slow it down. I tried it on my laptop
> with 2 cores and on a powerful computer with 12 cores, with different sizes
> of processed blocks and I didn't get any significant speed-up. The most
> costly seems to be writing of the three 3D rasters and the gradient
> computation is relatively short. I also tested different cache settings but
> default settings seems to be optimal, I got only similar or worse results
> with different cache settings.  I hope I didn't missed anything, since this
> is quite new to me.
>
> Best,
>
> Anna
>
>
> Doug
>>
>>
>> On Fri, Aug 1, 2014 at 3:54 PM, Anna Petrášová <kratochanna at gmail.com>
>> wrote:
>>
>>> Hi,
>>>
>>> 1. What did you get done this week:
>>> I implemented adding attributes to each segment of a flowline. I added
>>> column with velocities and values of input 3D raster along the flowline.
>>> The result can be visualized by using vector color tables (v.colors) in 2D
>>> and 3D.
>>> I started writing r3.gradient module based on the gradient function in
>>> r3.flow. The module is already running and giving correct results, I will
>>> add it to addons once the gradient function is moved to library.
>>>
>>> 2. What do you plan on doing next week?
>>> I will try to parallelize the gradient computation with openMP, the
>>> structure of the code is already prepared for that. Then, I plan to add
>>> more tests.
>>>
>>> 3. Are you blocked on anything?
>>> No.
>>>
>>> Anna
>>>
>>> [1]
>>> http://trac.osgeo.org/grass/wiki/GSoC/2014/ImplementationOf3DRasterFlowLine
>>> [2]
>>> http://trac.osgeo.org/grass/browser/grass-addons/grass7/raster3d/r3.flow
>>>
>>> _______________________________________________
>>> grass-dev mailing list
>>> grass-dev at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/grass-dev
>>>
>>
>>
>>
>> --
>> Doug Newcomb
>> USFWS
>> Raleigh, NC
>> 919-856-4520 ext. 14 doug_newcomb at fws.gov
>>
>> ---------------------------------------------------------------------------------------------------------
>> The opinions I express are my own and are not representative of the
>> official policy of the U.S.Fish and Wildlife Service or Dept. of the
>> Interior.   Life is too short for undocumented, proprietary data formats.
>>
>
>


-- 
Doug Newcomb
USFWS
Raleigh, NC
919-856-4520 ext. 14 doug_newcomb at fws.gov
---------------------------------------------------------------------------------------------------------
The opinions I express are my own and are not representative of the
official policy of the U.S.Fish and Wildlife Service or Dept. of the
Interior.   Life is too short for undocumented, proprietary data formats.
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