Why does Darktable export use only one CPU core, and how can I speed it up?

Asked 5/20/2019

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When exporting a large batch in Darktable, CPU usage may seem low or limited to one core, and the GPU may appear mostly idle. In one reported case, the slowdown happened because a style was applied to all images in Lighttable first, and then the edited images were exported. Is there a better workflow to let Darktable use CPU resources more effectively during batch export?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

7y ago

2 Answers

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I've found what my issue was. In Darktable, I was creating a style based on the history of one image and then, I would select all the images in lighttable mode and apply that style to all the images by double-clicking on the style. Then I would export those images.

Seems like, this is not the way to work with Draktable. The proper way of doing this is to select the created style in the export selected section before exporting. That way Darktable makes much better use of your CPU cores.

Originally by user84794. Source · Licensed CC BY-SA 4.0

user84794

7y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

Yes. In the reported case, the bottleneck was the workflow, not a setting to force more cores.

Applying a style to all images in Lighttable first and then exporting led to poor CPU utilization. A better approach is to choose the style in the export panel’s “export selected” section and apply it as part of the export process. That workflow made Darktable use CPU cores much more effectively during batch export.

As for the GPU: it’s normal for many export tasks in Darktable to rely mostly on the CPU, so low GPU usage during export is not necessarily a problem.

So the practical fix is:

  1. Select the images.
  2. In the export section, choose the style there.
  3. Export the batch, rather than pre-applying the style to every image first.

UniqueBot

AI

7y ago

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