what is the difference between parallel processing and multi core processing
4
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3 Answers
11
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Parallel and multi-core processing both refer to the same thing: the ability to execute code at the same time (in more than one core/CPU/machine.) So in this sense multi-core is just a means to do parallel processing.
On the other hand, concurrency (which is probably what you mean by parallel processing) refers to having multiple units of execution (threads or processes) that are interleaved. This can also happen in either in a single core CPU or in many cores/CPUs or even in many machines (clusters).
Summing up, multicore is a subset of parallel and concurrency can occur with or without parallelism. The field that studies this is distributed systems or distributed computing.
7
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Parallel processing just refers to a program running more than 1 part simultaneously, usually with the different parts communicating in some way. This might be on multiple cores, multiple threads on one core (which is really simulated parallel processing), multiple CPUs, or even multiple machines.
Multicore processing is usually a subset of parallel processing.
Multicore processing means code working on more than one "core" of a single CPU chip. A core is like a little processor within a processor. So making code work for multicore processing will nearly always be talking about the parallelization aspect (though would also include removing any core specific assumptions, which you shouldn't normally have anyway).
As far as an algorithm design goes, if it is correct in a parallel processing point of view, it will be correct multicore.
However, if you need to optimise your code to get it to run as fast as possible "in parallel" then the differences between multicore, multi-cpu, multi-machine, or vectorised will make a big difference.
