MEMORY MANAGEMENT: Putting boxes in a warehouse: Box of size 200One Box is removed One new box added and one old box removed Another new box added It is an exact analogy of allocation of Memory space to various processes within a program Now consider a situation where memory is of size 2000, and at some stage after some allocation the memory map looks like followingwhere the free space segments are of sizes 200, 100 , 400 and 400. Let us try to allocate space for size 100. This can fit in any of the free segments. 3 Strategies: First Fit Strategy: Find first hole that is big enoughIf no strategy works one could concatenate the used segments to create larger holes Compaction: There are various forms of compaction. It involves movement of data and updating of links. One form involves moving allocated memory blocks to left side one by one. Other forms could involve moving all the blocks together to left hand side as shown below: Best Fit Strategy: Find smallest hole that is big enough Worst Fit Strategy: Use largest holeA process has several segments. It is possible to store the segments in consecutive holes available. COMPACTION USED UNUSED SEGMENTS Process 1 has 3 segments of size 200+300+100 Process 2 has 2 segments of size 300 + 300 Process 3 has 1 segment of size 300 Unused Memory space of size 5003 Processes stored in memory of size
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