Hmm... strange. The documentation is a bit confusing: - http://www.darktable.org/usermanual/ch06s02.html.php 'number of background threads: This controls how many parallel threads are used to create thumbnails during import. On 32bit systems it is strongly recommended to set this to 1. Needs a restart if changed (default 2).' - http://www.darktable.org/usermanual/ch08.html.php#d0e15770 'number of background threads: This parameter defines the maximum number of threads that are allowed in parallel when importing film rolls or doing other background stuff. For obvious reasons on 32-bit systems you can only have one thread eating resources at a time. So you need set this parameter to 1; anything higher will kill you. For the same reason you also must set the number of parallel export threads to 1.'
Note the 2nd definition includes 'or doing other background stuff', and also mentions a setting 'parallel export threads'; that seems to refer to a setting called 'parallel_export' (default=1): 'set this variable to num_threads if you want multithreaded export to process multiple images at a time. be warned: every thread will need at the very least 1GB of memory. setting this to 1 switches on per-image parallelization'. According to the blog entry on OpenCL (http://www.darktable.org/2012/03/darktable-and-opencl/), it's best left at the default of 1: 'Before going into the details, the above already makes clear that we should not process several images in parallel with OpenCL. We already make maximum use of GPU memory by tiling and the nature of GPU processing will already parallelize processing to the max on a pixel by pixel basis. No room for additional parallelization. In preferences set "export multiple images in parallel" to 1.' Thanks for the info, Kofa On 6 October 2014 14:53, Markus Jung <[email protected]> wrote: > Because it is not just one thread ;) > > darktable exploits parallelization at different levels. Most, if not all > modules distribute their computations automagically to different > threads. Adding more concurrency by running several rendering pipes in > parallel will most likely have a negative performance impact because of > negative cache effects and increased overhead. > Additionally, this option does only affect the thumbnail generation > process. I have not observed the CPU usage during thumbnail generation, > but i am assuming there is not much benefit from running it in parallel. > > Regards, > Markus > > Am 06.10.2014 um 14:43 schrieb KOVÁCS István: >> Why do you limit yourself to just 1 thread? On my system (4 GB RAM, >> old dual-core CPU) 2 threads work fine with 8 GB of swap space. >> >> On 6 October 2014 11:38, Markus Jung <[email protected]> wrote: >>> Hello Bernhard, >>> >>> most likley, something with your darktable configuration went wrong. >>> Please take a look at your core preferences: >>> http://www.darktable.org/usermanual/ch06s02.html.php >>> >>> I am using (with the same amount of RAM): >>> mipmap cache: 1536 >>> background threads: 1 >>> host memory limit: 4096 >>> minimum single buffer size: 16 >>> >>> Regards, >>> Markus > > > ------------------------------------------------------------------------------ > Slashdot TV. Videos for Nerds. Stuff that Matters. > http://pubads.g.doubleclick.net/gampad/clk?id=160591471&iu=/4140/ostg.clktrk > _______________________________________________ > Darktable-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/darktable-users ------------------------------------------------------------------------------ Slashdot TV. Videos for Nerds. Stuff that Matters. http://pubads.g.doubleclick.net/gampad/clk?id=160591471&iu=/4140/ostg.clktrk _______________________________________________ Darktable-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-users
