Thursday, December 13, 2007

assignment #3.0

pg. 56
question# 1-3
a. Multiprogramming. Why is it used?-Multiprogramming makes effifcient use of the CPU by overlapping the demands for the CPU and its I/O devices from various users. It attempts to increase CPU utilization by always having something for the CPU to execute.b. Internal fragmentation. How does it occur?Experiencing Internal Fragmentation Errors only when the IMG function tries to create a partition. Problem occurs when version 4.01 tries to create a partition during the image restore process. Pieces of files within a designated swap file area become fragmented. c. External fragmentation. How does it occur?the external fragmentation is to create a minimum swap file size that somewhat exceeds the usual size of your swap file. If your swap file exceeds the minimum, external fragmentation will occur. Setting a maximum that may be exceed is ill advised as it can crash your system if it is exceeded.d. Compaction. Why is it needed?e. Relocation. How often should it be performed?relocation is the process of replacing symbolic references or names of libraries with actual usable addresses in memory before running a program. It is typically done by the linker during compilation, although it can be done at run-time by a loader. Compilers or assemblers typically generate the executable with zero as the lower-most, starting address. Before the execution of object code, these addresses should be adjusted so that they denote the correct runtime addresses.2. Describe the major disadvantages for each of the four memory allocation schemes presented in the chapter.3. Describe the major advantages for each of the memory allocation schemes presented in the chapter.-

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