Paged segmentation and segmented paging are two memory management techniques that offer the advantages of both paging and segmentation, and
A memory management technique known as Segmentation with Paging in OS combines the benefits of both segmentation and paging.
The main memory is split into variable-size segments, which are subsequently partitioned into segmentation with paging in os"smaller fixed-size disk pages. Each segment has a page table, and each process has many page tables.
Each table includes information for each segment page, whereas the segment table has information for each segment. Page tables are linked to segment tables and segment tables to individual pages within a segment.
Segmented paging is a way to manage computer memory that breaks it into small chunks called segments, and within each segment, there are fixed-sized pages. It's like dividing a big book into chapters, and each chapter into pages, to make it easier to read and manage.
Pages are created from segments. Implementation necessitates STR (segment table register) and PMT (page map table).
Each virtual address in this method consists of a segment number, a page number, and an offset within that page. The segment number indexes into the segment table, which returns the page table's base address for that segment.
The page number is an index into the page table, each item of which represents a page frame. The physical address is obtained by adding the PFN (page frame number) and the offset. As a result, addressing may be defined by the function:
va is the virtual address,
s determines the number of segments (size of ST),
p determines the number of pages per segment (size of PT),
d determines page size.
address_map(s, p, w)
pa = *(*(STR+s)+p)+w;
Advantages of Segmented Paging
The benefits of segmented paging are as follows:
- Each segment is represented by a single entry in the segment table. It lowers memory use
- The segment size determines the size of the Page Table
- It reduce the issue of external fragmentation
Disadvantages of Segmented Paging
The downsides of segmented paging are as follows:
- Internal fragmentation plagues segmented paging
- When compared to paging, the complexity level is substantially higher
- Managing both segmentation and paging tables increases overhead
- Require additional effort to design and implement