what's the difference between a multi-cpu , multi-core and a multi-thread system ?
 

hi ,

please the answer the question for me in the title (for cpu experts only)
btw i do have an understanding of what a cpu/core/thread is but these days parallel computing is getting more and more advanced and therefore more and more convoluted to the extent that many times i don't know which one is which :confused:

for instance i do remember that a multi-cpu is a system with more than 1 physical cpu chips connected to the same bus system and sharing the same memory such as in SMP.
and that a multicore system is one with a single cpu die which has more than 2 "cores" inside however i'm now hearing about multi-cpu system with 2 cpu's inside the same die ....so which one is which ...huh ??

and what about multi-threading or hyperthreading as in the P4 ?

OKay i'm now OFFICIALLY confused ?!?!?!?!

if you're a cpu expert i'd gladly appreciate your opinion on the subject within 10-50 lines or so (please don't throw a text book at me)

thanks in advance

I am not an expert, but I feel I can answer this.

Multi-core and Multi-cpu for almost all instances is the same. It really is the same to a common user. For example 2 cpu's that have 2 cores would for the most part create a computer with 4 processors.

Threads are how an OS and application are written and used. Threads are parts of a task that can be distributed to processors and later combined.

Hyperthreading is a cheat in some ways. For example a single die device that has a hybrid of single processor and dual processor within. In some ways it is a dual core and in some ways it is a single core. Some parts are not fully duplicated but some are.

So, to take advantage of a system that has more than one processor you need to have all three things. More than one processor, an operating system that can use processors and an application that can use processors.

Symmetrical Multiprocessing is all processors available to work at the same rate. Some multiprocessor systems have sort of a traffic cop processor that sends tasks to other processors.

Both exist.

BTW, you've used 'die' wrongly. CPUs are made by printing a wafer, then splitting the wafer into dies. With single core CPUs, each die is a CPU. With multicore CPUs, there can be several CPUs on each die.

Almost all current multicore CPUs are a single die. The only current dual-die multicore CPU I know of is the opteron 'Magny-Cours' 8/12 core CPUs. They used to be far more common, the pentium d CPUs were pretty much just 2 P4 dies stuck together. The Core 2 Quads were the same, 2 dual-core Core 2 Duo dies stuck together.

Wait, how did i use "die" wrongly ?
as far as i can tell you gave the same description that i was giving , didn't you?

cheers

I was actually extrapolating what you were asking, in the bit of your question that I quoted you didnt really ask anything, just changed terminology (from 'core' to 'CPU').

I think that what you were asking is 'do multicore systems have a single core per die? Or can there be multipule cores per die, and can there be mutlipule die multicores?'

Maybe you were asking something else, its a bit confusing the way your switched from 'core' to 'CPU'. If you were, can you please try to reword your question?

I assume your question to be about common desktop x86 processors. If you start to include all the other systems out there the answer would not be easy to answer. When intel and others started selling a cpu as such the current systems used processing boards or processing units. They were not a single device but collections of boards and chips to process data. Many are still in use today.

As for parallel processing it is still limited to industrial and scientific and government tasks for the most part. That would also depend on some assumptions. I don't know of any home user that is able to use parallel processing to do soho tasks.

The main difference between multicore systems and multiprocessor systems, which have been available for many years, is that multicore systems include a single physical processor that contains two or more cores while multiprocessor systems include two or more physical processors. Multicore systems also share computing resources that are often duplicated in multiprocessor systems, such as the L2 cache and front-side bus. Multicore systems provide similar performance to multiprocessor systems, but often at a significantly a lower cost. The reason is that a multicore processor does not cost as much as multiple equivalent individual processors, and a motherboard with support for multiple processors, such as multiple processor sockets, is not required.





:confused:
George Shelter
Ambit Energy, Sales Consultant
Carthage, Missouri

Okay if that's the case, then please STOP extrapolating because you're getting the wrong end of the question !
you need to :D
btw i don't see how i "switched" any terms , you're just confusing yourself unnecessarily (and me too)
anyways the question (the original one not the one you extrapolated) has been fully answered to my satisfaction ...
Thank you for your effort :)

Well i'm doing parallel processing right now actually with the courtesy of "make -j 2" compilation is running dual core ..wehhe !
but then i again i don't think i fit the description of "home user" more like "nerd user" so yeah you could be right about that ...LOL


HI FIVE for you Sir , you've provided the best of all answers in this Thread and welcome to the forum :)

If Ambit Pros answer was what you were after, then you've worded your question really oddly.

Are you not a native english speaker? If not, then fair enough, english can be confusing. If you do speak english, reread-

A mutlicore is a single CPU die with 2 cores inside.....and then you say a mutli-CPU system with 2 CPUs in the same die? That is just a rewording.

i'm not interested in arguing with you over nothing , as i said the question has been answered satisfactorily...
no need to keep your mind occupied with this ... you can move on to something else :)

Thanks for Efforts

We are indeed speaking in quite different terms.

Well this is what happens when somebody "extrapolates" on things , better known as Taking things out of Context!
If he were to put the phrase "but now i'm hearing about" back into the quote (i.e put the sentence back into its context) then things would make sense.

first he says that i'm using "die" wrongly then he claims that i've "switched" the terms "cpu" and "core"....yeah right of course this all happens in a thread (WARNING not to confuse with computer threads, believe me this happened before, no kidding!) whose purpose is to make a distinction between "cpu/processor" , "cores" and "threads" (as in hyperthreading) ....DOH !!

some folks just love nitpicking http://en.wikipedia.org/wiki/Nitpicking some even go further and plant the nit so they can pick them later on ...LOL

i guess it has to be a hobby or something.