memory management - Differences or similarities between Segmented paging and Paged segmentation? -


i studying combined paging/segmentation systems , in book there 2 approaches :

1.paged segmentation 2.segmented paging

i not make out difference between two. think in paged segmentation segment divided pages , in segmented paging pages divided segments, though don't know if right or wrong. meanwhile on internet combined paging/segmentation described using 1 scheme only. can't figure out why in coursebook there 2 schemes this. appreciated.

so,after vigorously searching on net difference or similarity between these 2 terms,i have come on final answer.first of write down similarities:

  • they both (segmented paging , paged segmentation) type of paging/segmentation combined systems (paging , segmentation can combined dividing each segment pages).
  • in both system segments divided pages.

now describe differences have define , describe each term separately:

  • segmented paging- segments divided pages.implementation requires str(segment table register) , pmt(page map table).in scheme, each virtual address consists of segment number, page number within segment , offset within page.the segment number indexes segment table yields base address of page table segment.the page number indexes page table,each of entry page frame.adding pfn(page frame number) , offset results in physical address.hence addressing can described following function :

va = (s,p,w) where, va virtual address, |s| determines number of segments (size of st), |p| determines number of pages per segment (size of pt), |w| determines page size.

address_map(s, p, w) { pa = *(*(str+s)+p)+w; return pa; }

the diagram here:

segmented paging

  • paged segmentation- segment table or page table may large keep in physical memory(they can reach mbs).therefore,the segment table divided pages , page table of st pages created. segment number broken page no.(s1) , page offset(s2) of page table of st pages.so,the virtual address can described :

va = (s1,s2,p,w)

address_map (s1, s2, p, w) { pa = *(*(*(str+s1)+s2)+p)+w; return pa; }

the diagram description here: paged segmentation


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