Parallelism based on Granularity size

Granularity:  Granularity or Grain size is a determine which measure how much computation is devoted in a process.Granularity size is determined by counting the number of instructions in a program section. The following types of grain sizes have been recognized (shown in Figure):

 1)   Fine Grain: This type includes approximately less than 20 instructions.

2)   Medium Grain: This type includes approximately less than 500 instructions.

3)   Coarse Grain: This type includes approximately greater than or identical to one thousand instructions.

Based on these Granularity sizes, parallelism can be specified at various stages in a program. These parallelism stages form a hierarchy according to which, lower the level, the greater is the granularity of the process. The degree of parallelism reduces with increase in level. Every stages according to a granularity size demands scheduling and communication overhead. Following are the parallelism levels (shown in Figure ):