I've been wondering recently why parallel processors weren't developed or utilized more, at least on personal computers, before 2004. It seems like a fairly obvious way to speed up the processor. So was it more due to the fact that ILP, clock rate, data size, etc. were just so easily improvable that it didn't make sense to focus on parallelism? Or were there some serious technical issues that had to be tackled before parallel cores became widespread?
bpr
@tclarke, before 2004, your computer would double in performance every ~2 years (often even less). Parallel processors were already in use in servers, but what do you do even today that regularly requires multiple processors in your desktop / laptop?
ferozenaina
Back then, it would have been cheaper for companies to increase clock speed than fabricate with two processor cores.
@bpr - when I'm running multiple programs + background processes (say browser, word processor, compiler and dropbox/anti-virus), wouldn't it have helped to have 2+ cores to handle threads simultaneously even pre-2004?
bpr
@ferozenaina, yes, it would have helped. But remember two things:
1) how often does a computer actually need more than one processor to run the required load? Desktop and laptop processors are mostly idle, so the benefit is small.
2) at the time, if you wanted multiple cores, then you bought multiple processors and a motherboard that had multiple sockets. If a processor company instead wanted to fabricate two cores, then each core would only have half as much chip area, and this would reduce the performance of each core.
I've been wondering recently why parallel processors weren't developed or utilized more, at least on personal computers, before 2004. It seems like a fairly obvious way to speed up the processor. So was it more due to the fact that ILP, clock rate, data size, etc. were just so easily improvable that it didn't make sense to focus on parallelism? Or were there some serious technical issues that had to be tackled before parallel cores became widespread?
@tclarke, before 2004, your computer would double in performance every ~2 years (often even less). Parallel processors were already in use in servers, but what do you do even today that regularly requires multiple processors in your desktop / laptop?
Back then, it would have been cheaper for companies to increase clock speed than fabricate with two processor cores.
@bpr - when I'm running multiple programs + background processes (say browser, word processor, compiler and dropbox/anti-virus), wouldn't it have helped to have 2+ cores to handle threads simultaneously even pre-2004?
@ferozenaina, yes, it would have helped. But remember two things: 1) how often does a computer actually need more than one processor to run the required load? Desktop and laptop processors are mostly idle, so the benefit is small. 2) at the time, if you wanted multiple cores, then you bought multiple processors and a motherboard that had multiple sockets. If a processor company instead wanted to fabricate two cores, then each core would only have half as much chip area, and this would reduce the performance of each core.