What is the effect of multi-core processors on the total time it takes to process information?

Question

I'm trying to understand the practical advantage of multi-core processors.
I've seen many questions on Yahoo Answers like "is Dual Core 1.5GHz as fast as single core 3GHz?" and they usually get an answer similar to "Well, it just means that the processors share the load and get it done faster but it doesn't mean anything is operating at 3Ghz"

My question is, aren't those answers sort of a theoretical cop-out? If they get the job done twice as fast then isn't it just like having a single-core 3Ghz processor even if neither processor is technically running at 3GHz?

To reframe the question: Say you have a very complex set of mathematical equations - Building a weather model, for instance, and a single core 1.5GHz processor gets it done in X amount of time.
Does that mean a Dual Core 1.5GHz processor gets it done in X/2 time and a Quad core gets it done in X/4 time? or is there some law of diminishing return when it comes to multi-core processors.
Let's assume the programming supports multi-threading.

Answer 1

Initially, during the race for speediest processor they focused on keeping cranking up the internal clock speed of the processor.

At some point, say around 3GHz, they could no longer ignore the insane amount of heat dissipated by the processor.

If you placed a metal sheet on the processor instead of the heat sink, you could literally fry a freaking egg on the thing!

The early 3 GHz chips consumed some 120 Watts, while emphasis on power consumption reduction was growing, due to all the talks about climate change.



Adding a bit of extra speed resulted in adding a LOT more heat.

The relationship wasn't just directly proportional.

They realized the way they were heading, they had just about reached the practical limit.



The methods they used in an attempt to combat blow-out in power consumption and also picking up on the race for speed once again was to use multi-core processors.

By lowering the core speed and increasing the number of cores, they could now reach the same and higher processing speeds in a more efficient chip.

In the meantime, further technology advances also allowed for further reduction of die size of the newer chips, and other power saving schemes were added, making them more efficient and candidates for pushing these up to insanely high core speeds once again.



That should clarify the reasoning behind splitting simpler single core processors into multi-core processors.



About the actual performance and relationships, whether 1.5 GHz dual core is same speed as 3.0 GHz single core, somewhat faster or somewhat slower (maybe due to overheads of signal distribution, etc.) I don't know.

Maybe someone else can enlighten that.

I expect it has also a lot to do with how well the operating system and the application handles it.

For an end user it probably suffices to check and compare some bench marks under a variety of conditions.

Answer 2

a quad core processor running at 1.5ghz is still faster than a dual core running at lets say 3.5ghz. The difference IS the number of cores. Picture one man loading boxes into a trailer by himself. It will take him much longer running back and forth from the pallet to the trailer than it would take four men standing in line passing boxes down to each other right? same thing with processors and cores. The more cores the better.

Answer 3

properly in accordance to me in Multi-center Processors the proximity of dissimilar CPU cores on the comparable die enables the cache coherency circuitry to function at a plenty bigger clock fee than is conceivable if the alerts might desire to holiday off-chip. those bigger high quality alerts enable extra archives to be despatched in a given term provided that person alerts might properly be shorter and don't might desire to be repeated as in lots of cases. A twin-center processor makes use of particularly much less means than 2 coupled single-center processors. however the biggest draw back is that addition to working device (OS) help, modifications to present day utility is had to maximise utilization of the computing factors provided by employing multi-center processors. additionally, the skill of multi-center processors to extend utility overall performance relies upon at using dissimilar threads interior purposes.