parallel computing speed question when the body of the parfor loop takes about 2 seconds
1 view (last 30 days)
I have a question about parallel:
parfor ii=1:N dosomething%% end
in the parfor loop, the time of dosomething is 2 seconds in each loop, and N is about 100. In that condition, is it efficient to use parfor here???
I feel confused about that as I test the time and find the more core I use, the more time I spend!!!!!! Could someone help to answer this question?!!!!
Ken Atwell on 13 May 2015
It really depends on what "dosomething" is doing. If it is pure computation, it should be a big win. If there is file or network I/O going on, your mileage will vary depending on the application and hardware.
Also keep an eye on memory usage on your computer -- if you're using all of your physical RAM, your computer may be spending much of its time swapping, more than offsetting and gain you'd get from multiprocessor operation.