There is also an overhead related to signalling or communications.

At some point, the primary processor needs to wait for the other processor(s) to finish. This takes execution time.Īnother item is the synchronization wait time. Minimally, the other processor (core) has to be set up to execute the thread core. Regardless of whether you have an OS or not, parallel programming has an overhead. There are many factors in performance with multiple threads or tasks. CPU for example if contains two cores/processors, it can dedicate one for this matrix and the other for all other interrupt handling and other programs, hence wait time will significantly reduce over time

But, when same 100*1000 matrix is handed over to parallel processing, it is broken down into reasonably small pieces and is operated upon by possibly more than one processor. In case, a large matrix, for example, a matrix of size 100*100 is handed over to a serial processor, the processor can't process this single program but has to handle all the interrupts, all other plethora of processes and hence wait time increases in this case. When this same 10*10 matrix is operated upon via parallel processing, it'll be broken down into smaller pieces which will then be fed to each of the individual processors (keep in mind, all this breaking the matrix and handling it over to each of the parallel processors requires time) and hence, performance of parallel processing reduces over small matrices. In a small matrix, for example, take a matrix of size 10*10, serial processing is favourable because a program wouldn't need to be broken down into smaller pieces and then carried onto the serial or single processor for further processing. Than I measured the time of each operations using on the big and small matricesĪnd I noted that on the small matrices the Serial processing was faster than Parallel processing but on the other hand Parallel processing had better preformance on the big matrices. Serial calculation just calculate m3, m3. We calculate m3 row i' with different threads. To use '*' and '+' operators with parallel processing and serial processing.Ĭonsider we have m1 and m2 matrices and m3 = m1 * m2. I have an implementation of a generic Matrix and I create an option

Serial processing operating system