On Friday 22 October 2010 11:34:19 ow...@netptc.net wrote: > In fact IIRC the additional overhead follows the square of the number > of CPUs. I seem to recall this was called Amdahl's Law after Gene > Amdahl of IBM (and later his own company)
Either that's not it, or there's more than one "Amdahl's law" -- the oen I know is about diminishing returns from increasing effort to parallelize code. I don't know it in its pithy form, but the gist of it is that you can only parallelize *some* of your code, because all algorithms have a certain amount of set-up and tear-down overhead that's typically serial. Even if you perfectly parallelize the parallelizable part of the code, so it runs N times faster, your application as a whole will run something less than N times faster, and as N gets large, this "serial offset" contribution will come to dominate the execution time, at which point additional investments in parallelization are probably wasted. -- A. -- Andrew Reid / rei...@bellatlantic.net -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/201010222005.49579.rei...@bellatlantic.net