Compare the memory organization schemes of contiguous memory allocation, pure segmentation, and pure paging with respect to the following issues External fragmentation?

Answer 1

1. Compare the memory organization schemes of contiguous memory allocation, pure segmentation, and pure paging with respect to the following issues: a. External fragmentation

b. Internal fragmentation

Answer 2

Contiguous memory allocation scheme suffers from external fragmentation as address spaces are allocated contiguously and holes develop as old processes die and new processes are initiated. It also does not allow processes to share code, since a process's virtual memory segment is not broken into non-contiguous fine-grained segments.

Pure segmentation also suffers from external fragmentation as a segment of a process is laid out contiguously in physical memory and fragmentation would occur as segments of dead processes are replaced by segments of new processes. Segmentation, however, enables processes to share code; for instance, two different processes could share a code segment but have distinct date segments.

Pure paging does not suffer from external fragmentation, but instead suffers from internal fragmentations. Processes are allocated in page granularity and if a page is not completely utilized, it results in internal fragmentation and a corresponding wastage of space. Paging also enables processes to share code at the granularity of pages.