Flashcards
CSCE 311 REview
Cards in this deck (6)
- 1why is non-contiguous allocation better?+exploits working set theory
-by cutting needed memory into segments or pages
-memory swapping occurs in some parts of the segment/ pages not-needed
+reduces fragmentation issue - 2Compare and contrast the 2 main examples of non-contiguous mem. allocation covered.-segmentation does not handle dynamic segments well while paging allows dynamic components to change flexibly
-swapping occurs at segments vs page level
-segments causes external fragmentation while paging causes internal fragmentation
-CONS: swapping slow for segments vs. address translation costly in paging - 3**Contiguous • What is updated at a process switch to assist address translation? • Can it keep program from accidentally overwriting its own code? • Can it share code/data with other processes?– Base & limit registers
– No
– No - 4What are the 2 registers needed in conitugous allocation translation?-Base and limit registers which you add together.
- 5How does Address translation for Segmentation occur?-Each process has a segmentation table which contains base information, bound information, and Read/Write Information.
Offset from virtual mem. + base information = physical address * for a particular segment - 6With segmentation, what is updated at process switch to assist address translation? • Recall that a segment can be swapped in/out memory. If a segment is swapped in and its location changes, what information in the table should be updated? • Can it keep program from accidentally overwriting its own code? • Can it share code/data with other processes?– Register that points to the segment table
– Base field of the entry describing the location of that segment in
physical memory
– Yes. Code segment can be set as read-only
– Yes. A physical segment can be pointed to by multiple processes