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Originally Posted by Randux
Hi guys,
Are these Intel dual and quad core chips really 2 and 4 individual processors or is it smoke and mirrors?
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Well, its not smoke and mirrors. And AMD have been, indirectly, making the slightly odd claim that an issue with the Intel quad core parts is that they aren't four CPUs on one die, which is slightly difficult to understand... (You might as well ignore this point! AMD is just trying to score meaningless marketing points off Intel here.)
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If you get one of these chips can you run a true SMP OS
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I'm not sure how this is a useful question. You can run an SMP OS on a single core processor. In fact, these days its often done in Linux. What you don't get, is any advantage out of doing it.
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or is it just that everything is transparent and you get approx. 2 or 4 times the power of one processor?
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I'd like to answer that question in three ways: Yes, No and It Depends.
Yes, under certain very particular circumstances, you can get a throughput approximately equal to double that of a single core at a similar frequency and with a similar amount of cache per core (and always assuming other things like the disk drives aren't a bottleneck). This may get close to occuring in, say, a server, where there are a myriad of little tasks queued for execution. It can also happen with certain specifically written apps (say applying transformations in a specifically optimised photo-processing app).
Also, No, it doesn't. This is also a correct answer. For certain apps, say one monolithic (single threaded) app, like many games (unless particularly re-written to take advantage of the cores) you get a throughput almost the same as a single core (with the usual conditions). Although, you could, maybe, be burning a CD at the same time, where, on a single core, your game might grind to a halt if you tried this kind of stupidity.
So, the real answer is probably, maybe. Maybe even definitively maybe. Somewhere in between in most cases. And if you only expect a small speed boost, then you are not going to be dissappointed. And that's probably what you'll see most of the time until apps are re-written. But the cost is small, and more and more apps will be re-written over time. And in a situation like a Linux box, there may be quite a few little processes that can be executed on the 'other' core from the one executing the 'big' application.
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I understand there is management overhead which makes 2 actual processors not as fast as 1 processor at twice the clock speed.
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Well, in most cases 'management overhead' wouldn't be quite the right description, but its the right general idea: you certainly don't simply get 2x or 4x performance.
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Are you saying these "cores" are like 2 completely separate functional processors?
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Yes. (Really, very nearly!) They are functionally separate processors. Depending on supplier (Intel and AMD) they have different arrangements with cache, and that cache sharing causes a small deviation from 2x or 4x, but that isn't the biggest problem (so you can ignore it, if you like, but you did ask).
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If they could make one CPU twice as fast at a comparable cost to a dual core they certainly would do that instead....Dual core is slightly better than two single core packages of the same specs,
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Depends somewhat on the definition of 'better' that you choose.
They could make one cpu with twice the clock speed, if that's what you mean, but the power issues would be a bit troublesome. Two cpu cores at half the clockspeed does not give you the same power consuption once we get into this regime in which power consumption climbs non-linearily with clockspeed.
Now 'one core with twice the clockspeed' may be a piece of silicon that could be churned out economically, but then there are many other costs that go into the system (bigger power supply, oh lets have watercooling or maybe even N2, fans). And then there is all the criticism that Intel got over the rather warm, and therefore noisy, Netburst Pentium D parts. You think Intel wants to go back there again? (Although avoiding a re-run of that particular debacle may not be their main motivation.) And, in particular, with all organisations claiming 'greenness', this isn't where Intel wants to be.
If your definition of 'better' leans heavily on power efficiency, then this is important. If you just want to frag the bad guys and don't care if you need your own electricity substation to do it, then that's rather different.