decrease in CPU for Parallel processing job with time

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Andy Daubenspeck 2019-7-17

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https://ww2.mathworks.cn/matlabcentral/answers/472212-decrease-in-cpu-for-parallel-processing-job-with-time

评论： Walter Roberson 2019-7-17

I am running a longish (~6 hour) simulation using the parallel processing toolbox. The Activity Monitor on my 4-core i7 iMac shows User activity of 75% of available CPU time with a small amount of idle time (~20%) at the start, but over time, the User fraction drops to <20% and the idle time increases to >75%. Can anyone explain this slowdown please?

Thanks,

Andy

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Andy Daubenspeck 2019-7-17

That makes sense though with only 4 cores working and 1000s of iterations left--I signal how far through the job along the way-- I would have expected a bit more attention to the task! The job did seem to take about as long as I had expected scaling up from previous, shorter runs, so your explanation makes sense.

Thank you!

Walter Roberson 2019-7-17

The factor I refer to would typically not be relevant until more than 90 percent was done, except in cases where there were big differences in processing time.

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