Is there a (or what is the) difference between a processor and a core?

[razorweb]

So the new Xbox360 specs were released and my friend and I were talking about it thusly:

A: "So the new Xbox has three processors."

B: "No, it has three cores. A core is not a processor."

A: "Yes, a core is a processor. They are effectively the same thing."

Who is right? Can anyone give a comprehensive explanation on this matter?

 

[Matthias99]

A "processor" is a chip that does processing.

Generally a "processor" contains one "core" (or "processing core") -- the hunk of silicon logic that actually does the processing. However, it is possible to have a "multi-core processor" -- a single "processor" (chip) that contains multiple logical processor cores.

It's not clear from the descriptions whether or not the "Xenon" (Xbox360) has multiple processor chips, or is a multi-core design. I know they were rumored to be using multi-core CPUs, but it hasn't been explicitly stated in the releases I've seen. It sounded more like they were using three separate CPUs that were each capable of running two threads simultaneously (like Intel's HyperThreading technology).

 

[Spencer278]

Originally posted by: Matthias99
A "processor" is a chip that does processing.

Generally a "processor" contains one "core" (or "processing core") -- the hunk of silicon logic that actually does the processing. However, it is possible to have a "multi-core processor" -- a single "processor" (chip) that contains multiple logical processor cores.

It's not clear from the descriptions whether or not the "Xenon" (Xbox360) has multiple processor chips, or is a multi-core design. I know they were rumored to be using multi-core CPUs, but it hasn't been explicitly stated in the releases I've seen. It sounded more like they were using three separate CPUs that were each capable of running two threads simultaneously (like Intel's HyperThreading technology).

I think they have a multi-core design. Basicly for a multi-core design you take your one processor copy and paste it and then decreases the size until it fits in the area you want. It is not the same thing as HyperThreading whcih is also implmented in the Xbox360.

Whether multiple dies is better then a one die with mutliple core is debatable. The multicore design limits cache size but allows for tigher intergation of two threads.

 

[TuxDave]

Originally posted by: Spencer278

Originally posted by: Matthias99
A "processor" is a chip that does processing.

Generally a "processor" contains one "core" (or "processing core") -- the hunk of silicon logic that actually does the processing. However, it is possible to have a "multi-core processor" -- a single "processor" (chip) that contains multiple logical processor cores.

It's not clear from the descriptions whether or not the "Xenon" (Xbox360) has multiple processor chips, or is a multi-core design. I know they were rumored to be using multi-core CPUs, but it hasn't been explicitly stated in the releases I've seen. It sounded more like they were using three separate CPUs that were each capable of running two threads simultaneously (like Intel's HyperThreading technology).

I think they have a multi-core design. Basicly for a multi-core design you take your one processor copy and paste it and then decreases the size until it fits in the area you want. It is not the same thing as HyperThreading whcih is also implmented in the Xbox360.

Whether multiple dies is better then a one die with mutliple core is debatable. The multicore design limits cache size but allows for tigher intergation of two threads.

I think multi-core designs also allow higher bandwidth between cores due to the reduced distance, increased number of wires and no bond wires to screw you over.

 

[kpb]

Processor typically refers to a single chip able to process information. Currently and for rescent memory typical computers have had a single processor capable of handling anything they needed to and working on one thing at a time. If you go back to the 486 or earlier days you might run into a Math coprocessor. It was a seperate additional processor designed just to do FP operations that the main processor couldn't do. 486 DX and anything pentium had the FP operations integrated into the main processor so you didn't run into any coprocessors since then in the typical sense.

Rescently the pentium 4's got hyperthreading. Simply put that was a way to pretend they could work on 2 things at once even tho they didn't have any additional resources to work with them. The processor it's self can still only perform the same number of integery, floating point etc operations that it could before. It can just now keep track of 2 things at once to work on with that single set of resources. Why would you do this? Because alot of the processors time is spent waiting. Waiting for information to be loaded from memory or cache. Waiting to find out the result of a branch etc. If one is thread is stuck waiting you can do work on the other thread. Potentially allowing you to spend more time actually doing work.

A core is a seperate logical using able to work on something of it's own. Taking the idea one step past hyperthreading and actually allowing it to completely work on 2 things simultainously. Why do that? Because it's become increasingly hard to make one thing run faster and to make chips run at higher speed. So if you can't make the chip run faster or make it work on one thing at a time faster you make it work on multiple things at once and get more total work done that way.

What exactly is duplicated in the chip to make a core depends on the chip. In the case of the pentium D chips it's pretty literally 2 pentium 4's in one chip. Nothing really shared and no real special high speed connections or shared resources. The pentium 4 doesn't really seem to have been designed with dual core's in mind. It just couldn't ramp up clock speeds like expected and had to find some way to keep up with amd.

Amd on the other hand is more complicated. The chip was designed with dual or more cores in mind. The on board memory controller and the HT links (connection to chip set and/or other chips depending on what processor it is exactly are shared). The core is connected to everything else by a crossbar which allows it to swich around which core is talking to what as needed to let them share resources. Previous single core amd chips have had this and it just really didn't do much. Each chip does have it's on L2 cache so those arent shared.

There isn't alot of info about the xbox 360 yet but I suspect that it's gonna be multicore just because using that many processors in a game system would probably get pretty expensive. They have said that each core can handle 2 threads and the PS3 happens to have a dual threaded ppc core in it made by IBM so there's some speculation that the same one is used in the xbox. If it is it could pretty easilly be 3 cores in once chip since the Cell processor in the PS3 has 6 additional specialized processing cores in it and could easily fit 2 more copies of the ppc core in it.

 

[razorweb]

I guess I am asking whether statement three in my original post is right. Is a core the same as a processor? Are the two words synonymous?

 

[f95toli]

No, they are not synonymous.

 

[FrankSchwab]

Sometimes they are synonymous, and sometimes they aren't; it depends on context.

In this context, I would argue that they are indeed the same thing. In just about any way you look at a processor system with multi-core CPU chips, it looks the same as a system made up of multiple, single-core chips. The schematic is different, and there are some optimizations that you might make differently because of how system resources (for example, the memory bus) are shared, but otherwise the differences are far smaller than the similarities.

I vote for Statements 1 and 3 being correct, and Statement 2 being pedantic and not really germane to the discussion.

 

[Mday]

A processor typically refers to a packaged item that's a chip. A core typically refers to the design of that processor. When you run into the multi-core processor, well that's a chip with multiple cores. Usually a core is a standalone unit. There can be a debate on how a core is truly defined. Usually a core is just the processing unit design. There can be other components designed onto the silicon other than the core, like cache or power regulation, etc. ie, the core is the MAIN part of the processor design. Some (few) will argue that the core also includes the cache and poewr regulation.

There is no real definition of a core or processor. A core, when referencing a processor, is ambiguous in meaning. A processor is usually just defined as a part that processes information.

Take this statement that I just made up:
This version of the processor has the same core design as the previous version, but with a larger cache and made in a new 0.9um process.

 

[razorweb]

I think a chip is different than a processor.

A processor is a subset of chips. I also believe that a core is a subset of processors.

therefore, you can have multiple cores in a processor, and multiple processors on a chip. is that correct?

to wit: could you have a dual processor with multiple cores on each processor? that would prove my theory that a core is not a processor.

 

[SuperTool]

Processor = Core(s) + Onchip Cache. A processor can have multiple cores, each running a thread (or two if it's SMP) plus some cache.

 

[ahurtt]

If your car is the processor, then the engine is the core.