[digiKam-users] How to have DK utilize multiple cores for maintenance tasks

[Chris Green]

Thomas D <sdktda at gmail.com> wrote:
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> 
> Hi,
> 
> As part of another thread, I just learned how to increase the max size of
> thumbnails.
> When enabling large thumbnails in DK, I also have to rebuild all the
> thumbnails.
> This, however, is a huge computational task that takes a long time.
> I noticed that DK seems to only utilize about 7 % CPU time. My machine has
> 6 cores and I would like DK to utilize multiple cores. Maybe it already
> does and I/O is the bottleneck? Or do I need to enable multi-threaded
> thumbnail rebuilding somewhere?
> 
Very, very few things use multiple cores.  The core i/o in the Linux
kernel isn't (as far as I know) multithreaded, nor are any of the
basic libraries.  Thus, even if you run lots of different 'things' at
the same time - e.g. firefox, digikam, a mail program, etc. the CPU
still only loads one processor.

I have seen a couple of programs which do actually use more than one
processor, one was a password cracking program and the other (if I
remember right) was an image processing program of some sort.

I think the reason these programs were able to use multiple CPUs is
that, once loaded they have all the data they need and don't interact
with anything else while 'thinking'.  It's thus relatively easy to
make them multi-threaded.

-- 
Chris Green
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