[GRASS-dev] [SoC] GSoC 2021 - Parallelization of raster modules for GRASS GIS

[Aaron Saw Min Sern]

Hi everyone,

Week 5 has concluded and here's my report for this week.

1) What did I get done this week?
To benchmark both r.mfilter and r.neighbor implementation, I have made use of the recently merged benchmark library on randomly generated raster using r.surf.fractal.

The preliminary result is as follows for both modules (y-axis - time/secs, x-axis - nprocs | benchmarked on my local workstation):
[cid:ab3537de-3128-4b41-89d0-248b273e37cf][cid:ba251de1-c387-4b3d-8e88-c3da9f94c378]
Furthermore, checks are done to compare between performance on master branch vs after implementation (nprocs = 1), and the results are comparable.

These two implementations make use of extensive disk I/O to write to temporary file buffer before transferring to the final raster file format. This behavior is default in r.mfilter, but is explicitly introduced in r.neighbors to allow for parallelization. Upon discussion with the mentors, we decided that we should make better use of memory over disk. Ideally, the user will be able to input the size of memory usage to be used for buffer. However, r.mfilter will still preserve its original usage of temporary files buffer.

2) What do I plan on doing next week?

  *   Complete rework of r.neighbors implementation
  *   Compare benchmark between the two implementations

3) Am I blocked on anything?
No major roadblock, but I need to catch up a bit to rework my r.neighbor implementation.

Thanks,
Aaron
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