Recently I've gotten into the habit of staring at the Task Manager on my computer during CPU, RAM, and HDD intensive tasks. One such task for the CPU is rendering large image files (i.e. 10187px x 5093px) in GIMP. Today I noticed that during the rendering process, only about 29% of my CPU was being used. GIMP capped out at around 25% which suggests that GIMP is only using one of my 4 cores for rendering. Looking into the preferences, I noticed there was an option to set how many CPUs or Cores I wanted GIMP to use but it was already set to four.

This confused me so I did some research and the only link I was able to find that explained anything was this one: http://www.artistsguidetogimp.com/?p=267 . In the article, the author explain which functions in GIMP actually use the amount of cores you set in the Preferences and rendering doesn't seem to be one of them.

My questions now are, is there any way to enable multi core rendering in GIMP? Is it even possible or does the current exporting code not support multi core rendering in any way? If there is no way to do this, are there plans to make it possible in future version of GIMP?

Thank you,

Kasim Ahmic

Alright, I'll test it out and see how the performance differs during exporting. Thanks! Also, how would I get in contact with Øyvind?

Kasim Ahmić

Sent from my iPhone

On Nov 20, 2015, at 10:35 AM, Alexandre Prokoudine wrote:

On Thu, Nov 19, 2015 at 3:15 AM, Kasim Ahmic wrote:

My questions now are, is there any way to enable multi core rendering in GIMP? Is it even possible or does the current exporting code not support multi core rendering in any way? If there is no way to do this, are there plans to make it possible in future version of GIMP?

There is _some_ experimental support in GEGL for multithreading. If you want to test it, please use GEGL_THREADS= in the environment along with dev version of GIMP.

E.g.

$ GEGL_THREADS=4 gimp-2.9

I'm not 100% sure which part of GIMP features are covered by multithreading via GEGL, Øyvind Kolås is your guy here.

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So after playing around with it, it's safe to say using GEGL_THREADS=4 doesn't help when it comes to exporting. It does seem to have an effect on scaling images however, but all that happens is 100% of my processor is used and then GIMP 2.9 crashes. It should also be noted that scaling down large images in GIMP 2.9 (whether GEGL_THREADS is used or not) just causes it to crash.

Oh well, hopefully more stable multi core usage is being worked on and isn't too far off. It would certainly help productivity!

Kasim Ahmić

Sent from my iPhone

On Nov 20, 2015, at 11:29 AM, Alexandre Prokoudine wrote:

20 нояб. 2015 г. 19:05 пользователь "Kasim Ahmic" написал:

Alright, I'll test it out and see how the performance differs during

exporting. Thanks! Also, how would I get in contact with Øyvind?

I don't know if he reads this list, but he does read gimp/gegl-developer lists.

Alex
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