Alain Martel <kua### [at] videotronca> wrote:
> So, you have one light and 8 target objects, or 2 lights and 4 target
> objects, or 4 lights and 2 target objects or 8 lights and 1 target object.
>
> The maximum number of threads used while photon mapping is the product
> of the number of light_source by the number of objects with a target block.
> To the best of my knowledge : Currently, it is not possible to divide
> that process between several threads. The algorithm used is strictly
> linear and can't get split between multiple threads.

Makes sense, thanks for clarifying.

However, POV-Ray 3.7 seems to log this incorrectly. With 16 CPU cores, 1 light
source and 3 target objects, I can clearly see 300% CPU usage during photon
mapping (so 3 cores are used), however, 19 threads instead of 3 threads are
logged.

Render Time:
  Photon Time:      0 hours  2 minutes 53 seconds (173.948 seconds)
              using 19 thread(s) with 456.834 CPU-seconds total
  Radiosity Time:   No radiosity
  Trace Time:       0 hours 11 minutes 12 seconds (672.855 seconds)
              using 16 thread(s) with 10100.757 CPU-seconds total


Regards,
Thomas.

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