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1、Four short words sum up what has lifted most successful individuals above the crowd: a little bit more.-author-date大连交大os第三章作业第一章作业第三章作业4、Consider a swapping a system in which memory consists of the following hole sizes in memory order: 10KB, 4KB, 20KB, 18KB, 7KB, 9KB, 12KB and 15KB. Which hole is t
2、aken for successive segment requests of(a) 12KB (b) 10KB (c)9KBFor first fie? Now repeat the question for best fit, worst fit and next fit.Solution:First fit10K4K20K18K7K9K12K15K12K10K9KNext fit10K4K20K18K7K9K12K15K12K10K9KBest fit10K4K20K18K7K9K12K15K12K10K9KWorst fit10K4K20K18K7K9K12K15K12K10K9K 5
3、、For each of the following decimal virtual addresses, compute the virtual page number and offset for a 4-KB page and for an 8-KB page: 20000, 32768, 60000.Solution:page size: 4K=4*1024=4096(1) 20000/4096=43616 page number is 4, offset is 3616(2) 32768/4096=8 page number is 8, offset is 0(3) 60000/40
4、96=142656 page number is 14, offset is 2656page size: 8K=8*1024=8192(1) 20000/8192=23616 page number is 2, offset is 3616(2) 32768/8192=4 page number is 4 offset is 0(3) 60000/8192=72656 page number is 7, offset is 265622. If FIFO page replacement is used with four page frames and eight pages, how m
5、any page faults will occur with the reference string 017237103 if the four frames are initially empty? Now repeat this problem for LRU.Solution:(a) FIFO: Page fault rate=6/10=60%01723271030000333333111111100777777772222222(b) LRU: Page fault rate=7/10=70%017232710300003333001111111117777777722222232
6、8. A computer has four page frames. The time of loading, time of last access, and the R and M bits for each page are as shown below (the timesa re in clock ticks):PageLoadedLast ref.RM012628010123026501214027000311028511(a) Which page will NRU replace?(b) Which page will FIFO replace?(c) Which page will LRU replace?(d) Which page will second chance replace?Solution:(a) Page 2 (2) (b) Page 3 (3) (c) Page 1 (1) (d) Page 2 (2)-