parallel_export has been dropped from the preferences dialogue some time ago because of the explained intrinsic parallelization.
Regards, Markus Am 06.10.2014 um 15:11 schrieb KOVÁCS István: > 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
