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Qualcomm Says Eight-Core Processors Are Dumb
itwbennett writes "Following rival MediaTek's announcement of plans to release an eight-core processor in the fourth quarter, Qualcomm has declared eight-core processors 'dumb'. 'You can't take eight lawnmower engines, put them together and now claim you have an eight-cylinder Ferrari. It just doesn't make sense,' Qualcomm's senior vice president Anand Chandrasekher said, according to a transcript of his comments to Taiwan media provided on Friday. Asked whether Qualcomm would one day launch its own octa-core processor, Chandrasekher said, 'We don't do dumb things.'"
Parallelization does introduce it's own overhead. Some problems can be made to run parallel very easily without much effort. For example, lets say you have an unordered database of names and you want to count how many letter "A"s are in each name. You can very easily divide the database into eight equal parts and send it off to eight cores for processing and they will happily churn away until you have your answer with almost no additional overhead.
However, different problems cant be as easily parallelized. For example, lets say you take the same database of names and you want to sort it alphabetically. You can send each chunk of the database off to be sorted on each core, but now you have 8 pieces of the database that are all sorted and need to be merged back into the original list. This extra work of merging and communicating becomes the overhead.
This is a very simple example, but for many problems the speed gained by parallelization is reduced for every new thread. So you might get an almost 50% speedup by adding a second core, but the third core will give you maybe only 20% speedup, and the fourth 15%, etc...
And as mentioned by others, parallelization is almost always done to improve performance, not efficiency. It would be more power efficient for the one core to do the job if you are measuring efficiency by something like cycles per watt. This doesnt make much sense in a mobile device whose paramount concern is to run a long time on a battery.