Gustafson’s law

Gustafson’s law :-

Gustafson's Law says that if you apply P processors to a task that has serial fraction f, scaling the task to take the same amount of time as before, the speedup is

Gustafson demonstrated with a 1024-processor system that the basic presumptions
in Amdahl’s Law are inappropriate for massive parallelism [Gustafson88].
Gustafson found that the underlying principle that “the problem size scales with
the number of processors, or with a more powerful processor, the problem
expands to make use of the increased facilities is inappropriate” [Gustafson88].

Gustafson’s empirical results demonstrated that the parallel or vector part of a
program scales with the problem size. Times for vector start-up, program loading,
serial bottlenecks, and I/O that make up the serial component of the run do not
grow with the problem size