Amdahl's law

In computer programming, Amdahl's law is that, in a program with parallel processing , a relatively few instruction s that have to be performed in sequence will have a limiting factor on program speedup such that adding more processor s may not make the program run faster. This is generally an argument against parallel processing for certain applications and, in general, against overstated claims for parallel computing. Others argue that the kinds of applications for which parallel processing is best suited tend to be larger problems in which scaling up the number of processors does indeed bring a corresponding improvement in throughput and performance.