Memory Management Techniques

• Memory Management Techniques

Fixed Partitioning
Divide memory into partitions at boot time, partition sizes may be equal or unequal but don’t change
Simple but has internal fragmentation

Dynamic Partitioning
Create partitions as programs loaded
Avoids internal fragmentation, but must deal with external fragmentation

Simple Paging
Divide memory into equal-size pages, load program into available pages
No external fragmentation, small amount of internal fragmentation

Simple Segmentation
Divide program into segments
No internal fragmentation, some external fragmentation

Virtual-Memory Paging
Paging, but not all pages need to be in memory at one time
Allows large virtual memory space
More multiprogramming, overhead

Virtual Memory Segmentation
Like simple segmentation, but not all segments need to be in memory at one time
Easy to share modules
More multiprogramming, overhead

https://docs.google.com/viewer?a=v&q=cache:8YjAHQb0WsgJ:students.cs.byu.edu/~cs345ta/slides/CS345%252007%2520-%2520Memory%2520Management.pptx+&hl=en&pid=bl&srcid=ADGEESgCkTvJun68Ifb56wDcyg5UIaf98eTH0IFvm9gsE6oAsmLlrKs_jsXrQzrgkqv1Ot5F69czi0QyAJFsyuJQb5HvJvmCunq0OVRK4Ua-_fltzaC4tgbr0TTHAKLB0EQS006encTP&sig=AHIEtbTBAEIAgB8FL91wo4AidAi3f1_Pqg

• Memory Management Techniques

http://www.cse.buffalo.edu/~bina/cse421/spring00/LEC78MemMgt/sld007.htm

• Memory Management 

Various techniques
Fixed partitions – easy to use, but internal fragmentation
Variable partitions – more efficient, but external fragmentation
Paging – use small, fixed size chunks, efficient for OS
Segmentation – manage in chunks from user’s perspective
Combine paging and segmentation to get benefits of both
https://docs.google.com/viewer?a=v&q=cache:DJU4mo7E0BEJ:cseweb.ucsd.edu/classes/fa05/cse120/lectures/120-l10.pdf+&hl=en&pid=bl&srcid=ADGEEShm17EKOhrz3fSiENcf4xqvERf9xpIdIbRzjSP1G5bePoGXLBQZXDWEwlOyZJT8fVV1Wg-umGfL58MZ5K3e6ctlgpfs2In8Tl1s34lWlXfFmJQ0oXH3bC0FlOiH5nSNTk_5c5os&sig=AHIEtbRZmbCW31WfvVYnEIJH-PasAsVMZQ