What do you mean by real and pseudo-parallelism?

Answer 1

Pseudo-parallelism is the parallelism effect where a single processor creates a illusion of parallel processing by switching processes(or context) at very small intervals such that it is unnoticable to the user. This creates the effect that multiple processes(threads or programs) are running simultaneously. What actually happens is, each process is given a finite time(very small) and the process executes its instruction during this period. At the end of this period, context switching occurs and the Operating System allocates a finite time for another process. The next process may or may not be allocated the same amount of time and the time allocated to each processes depend upon their priority. On the other hand, Real parallelism applies to multi-processor(or multicore) system where each processor(or core) initiates its own sets of processes. Note that, it is possible that when a multi-core processor is performing Real Parallelism, each core might be performing Pseudo-parallelism amongst the processes(or threads) it is currently running.