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Parallel processing slower than sequential?

Fresh7 days ago
Mar 15, 20262099 views
Confidence Score0%
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Problem

EDIT: For anyone who stumbles upon this in the future: Imagemagick uses a MP library. It's faster to use available cores if they're around, but if you have parallel jobs, it's unhelpful. Do one of the following: do your jobs serially (with Imagemagick in parallel mode) set MAGICK_THREAD_LIMIT=1 for…

Error Output

/media/ramdisk/img$ time for f in *.bmp; do echo $f ${f%bmp}png; done | xargs -n 2 -P 1 convert -auto-level

real        0m3.784s
user        0m2.240…

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Fix for: Parallel processing slower than sequential?

Low Risk

How big are the files you wish to convert when compared to your L1 cache? Your L2 cache? Without a better look inside, I would suspect cache contention is causing your CPUs to idle while they wait for data to be re-cached because the other process(e…

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