Jacques Lucke 658fd8df0b Geometry Nodes: refactor multi-threading in field evaluation
Previously, there was a fixed grain size for all multi-functions. That was
not sufficient because some functions could benefit a lot from smaller
grain sizes.

This refactors adds a new `MultiFunction::call_auto` method which has the
same effect as just calling `MultiFunction::call` but additionally figures
out how to execute the specific multi-function efficiently. It determines
a good grain size and decides whether the mask indices should be shifted
or not.

Most multi-function evaluations benefit from this, but medium sized work
loads (1000 - 50000 elements) benefit from it the most. Especially when
expensive multi-functions (e.g. noise) is involved. This is because for
smaller work loads, threading is rarely used and for larger work loads
threading worked fine before already.

With this patch, multi-functions can specify execution hints, that allow
the caller to execute it most efficiently. These execution hints still
have to be added to more functions.

Some performance measurements of a field evaluation involving noise and
math nodes, ordered by the number of elements being evaluated:
```
1,000,000: 133 ms   -> 120 ms
  100,000:  30 ms   ->  18 ms
   10,000:  20 ms   ->   2.7 ms
    1,000:   4 ms   ->   0.5 ms
      100:   0.5 ms ->   0.4 ms
```
2021-11-26 11:06:16 +01:00
2021-10-23 10:49:51 +05:30
2021-11-24 15:54:53 +01:00
2021-03-26 16:15:02 +01:00

.. Keep this document short & concise,
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   See 'release/text/readme.html' for the end user read-me.


Blender
=======

Blender is the free and open source 3D creation suite.
It supports the entirety of the 3D pipeline-modeling, rigging, animation, simulation, rendering, compositing,
motion tracking and video editing.

.. figure:: https://code.blender.org/wp-content/uploads/2018/12/springrg.jpg
   :scale: 50 %
   :align: center


Project Pages
-------------

- `Main Website <http://www.blender.org>`__
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-----------

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License
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Blender as a whole is licensed under the GNU General Public License, Version 3.
Individual files may have a different, but compatible license.

See `blender.org/about/license <https://www.blender.org/about/license>`__ for details.
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