OpenMP & throughput

The number of algorithms in development GraphicsMagick which have been 
updated for OpenMP and verified to run much faster continues to grow. 
Unfortunately, testing suggests that certain basic bottlenecks in 
common operations such as reading/writing files and the 'resize' 
algorithm take up the majority of the time so throughput of certain 
operations that I often do is not improved very much.

Complex operations on medium to large images should definitely benefit 
significantly from OpenMP since the image processing times are 
dramatically improved.  However simple one-shot type operations are 
often not going much faster.  For example, this the command I often 
use to prepare a smaller set of images to mail to people:

   gm mogrify -output-directory ~/pics -resize 40% -sharpen 0x0.5 *.jpg

But as it turns out, the -resize still takes a lot of time and OpenMP 
only really helps it when creating thumbnail sized images.  To me, 
this means that OpenMP has been inserted in the wrong spot for resize.

As usual, I will try to address bottlenecks to the best of my 
abilities.

I still await feedback from others as to what benefits (or not) they 
are seeing from an OpenMP-infused GraphicsMagick.

Bob
======================================
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/


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