Scheduling Theory and types of “speed-up”
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Re:Diminishing rate of return (Score:4, Interesting)
by godrik (1287354) on Wednesday March 10, @11:46PM (#31434598)
There are two things here. Several things can happen in term of ’scheduling theory’
-you can have ’super linear speed up’ : put 2 workers and go 4 times faster. Think about building an ikea furniture that REQUIRES 2 people alone. Or about specialized workers : it might be better to add a microwave to a kitchen than a second oven. In computer systems, cache/memory can lead to super linear speed or dedicated hardware acceleration like graphic cards.
-you can have ‘linear speed up’ : put 2 workers and go 2 times faster. This is usally the case when the problem can be divided in a lot of independent task like painting 20000 doors. In computer systems this happens when uncompressing videos for instance.
-you can have ’sublinear speed up’ : put 2 workers and go 1.3 times faster. This happens when you need to do extra work to allow some several workers to work at the same time. As in tagging files so that other people can handle them (In computer science, computing a prefix sum array in parallel follows this principle). It also happens when there is not enough work for everybody (the 9 pregnant women case)
-you can also have ‘negative speed up’ : put 2 workers and go 1.3 times slower. This happens when people get in each others way fighting for the brush to paint. In computer systems, this is often the case when adding processors increase communication too much.
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