Legacy ImageMagick Discussions Archive

Hi, all
Environment: centos6.0, 16 cores, 8G mem
My lab want to use magick++ to sample local images(the number of images is about 70,000). i write an auto-processing program using c to sample the images. when run it by single thread, type top in command line, found that CPU usage is about 1400-1500%. when run it by multi-thread, CPU usage is however about 150-300%. After reading some articales on the forum, i re-install from the source configured with --disable-openmp, under single thread, CPU usage is about 90-200%, multi-thread is about 200-300%. Obviously time cost increase 3 times.
The work is done, but i want to know why. Or i can control it's CPU usage. Or i can use the IM effectively. it's just personal interests.
thanks all.

mem usage is normal about 0.8%

See MAGICK_THROTTLE @ http://www.imagemagick.org/script/resou ... nvironment. It periodically yields the CPU for at least the time specified in milliseconds. You can also set this value in the policy.xml configuration file.

i modify the policy.xml in install dir,<policy domain="resource" name="throttle" value="10"/>
CPU usage is normal. But it's not the result i want. If there is a compatible way that cut down the
CPU usage and do not slow the process,cost more time
i just want to find out a acceptable way to use the IM. Forgive me that i only deep into IM only several weeks,
IM needs more detail knowlege to understand for me.
thank u, magick.

Try setting the threads policy. The default is to use all the cores. You could set it to 1, to only use one core.

magick wrote:Try setting the threads policy. The default is to use all the cores. You could set it to 1, to only use one core.

i just tried, it doesn't work.<policy domain="resource" name="thread" value="1"/>. the experiment result indicates just CPU usage abnormal(1300-1500%).
If i configure IM with --disable-openmp, the CPU usage is about 100%. Parhaps it's the solution?