Memory Management with Bitmaps

Memory Management with Linked Lists

• Figure 3-7. Four neighbor combinations for the terminating process, X.

• Tanenbaum & Bos, Modern Operating Systems: 4th ed., Global Edition (c) 2015 Pearson Education Limited. All rights reserved.

Memory Management Algorithms

• First fit
• Next fit
• Best fit
• Worst fit
• Quick fit

• Tanenbaum & Bos, Modern Operating Systems: 4th ed., Global Edition (c) 2015 Pearson Education Limited. All rights reserved.

Virtual Memory

• There is a need to run programs that are too large to fit in memory
• Solution adopted in the 1960s, split programs into little pieces, called overlays
• Kept on the disk, swapped in and out of memory
• Virtual memory : each program has its own address space, broken up into chunks called pages

• Tanenbaum & Bos, Modern Operating Systems: 4th ed., Global Edition (c) 2015 Pearson Education Limited. All rights reserved.

Paging (1)

• Figure 3-8. The position and function of the MMU. Here the MMU is shown as being a part of the CPU chip because it commonly is nowadays. However, logically it could be a separate chip and was years ago.

• Tanenbaum & Bos, Modern Operating Systems: 4th ed., Global Edition (c) 2015 Pearson Education Limited. All rights reserved.

Paging (2)

• Figure 3-9. The relation between virtual addresses and physical memory addresses is given by the page table. Every page begins on a multiple of 4096 and ends 4095 addresses higher, so 4K–8K really means 4096–8191 and 8K to 12K means 8192–12287

• Tanenbaum & Bos, Modern Operating Systems: 4th ed., Global Edition (c) 2015 Pearson Education Limited. All rights reserved.

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