由于我用的Linux没安装tk，这里使用windows系统来模拟。仅写出命令和最后的统计结果。
- 问题 1 答案
ostep-homework-master\file-disks> python disk.py -a 0 -G
REQUESTS ['0']
Block: 0 Seek: 0 Rotate:165 Transfer: 30 Total: 195
TOTALS Seek: 0 Rotate:165 Transfer: 30 Total: 195
ostep-homework-master\file-disks> python disk.py -a 6 -G
REQUESTS ['6']
Block: 6 Seek: 0 Rotate:345 Transfer: 30 Total: 375
TOTALS Seek: 0 Rotate:345 Transfer: 30 Total: 375
ostep-homework-master\file-disks> python disk.py -a 30 -G
REQUESTS ['30']
Block: 30 Seek: 80 Rotate:265 Transfer: 30 Total: 375
TOTALS Seek: 80 Rotate:265 Transfer: 30 Total: 375
ostep-homework-master\file-disks> python disk.py -a 7,30,8 -G
REQUESTS ['7', '30', '8']
Block: 7 Seek: 0 Rotate: 15 Transfer: 30 Total: 45
Block: 30 Seek: 80 Rotate:220 Transfer: 30 Total: 330
Block: 8 Seek: 80 Rotate:310 Transfer: 30 Total: 420
TOTALS Seek:160 Rotate:545 Transfer: 90 Total: 795
ostep-homework-master\file-disks> python disk.py -a 10,11,12,13 -G
REQUESTS ['10', '11', '12', '13']
Block: 10 Seek: 0 Rotate:105 Transfer: 30 Total: 135
Block: 11 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 12 Seek: 40 Rotate:320 Transfer: 30 Total: 390
Block: 13 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
TOTALS Seek: 40 Rotate:425 Transfer:120 Total: 585
-
问题 2 答案
组合太多，这里就不给结果了。
对于没有寻道的请求无变化，有寻道的请求有时间变化。 -
问题 3 答案
组合太多，这里就不给结果了。
所有的请求的旋转时间都变慢了。 -
问题 4 答案
FIFO就是顺序执行。
ostep-homework-master\file-disks> python disk.py -a 7,30,8 -p SSTF -G
REQUESTS ['7', '30', '8']
Block: 7 Seek: 0 Rotate: 15 Transfer: 30 Total: 45
Block: 8 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 30 Seek: 80 Rotate:190 Transfer: 30 Total: 300
TOTALS Seek: 80 Rotate:205 Transfer: 90 Total: 375
- 问题 5 答案
ostep-homework-master\file-disks> python disk.py -a 7,30,8 -p SATF -G
REQUESTS ['7', '30', '8']
Block: 7 Seek: 0 Rotate: 15 Transfer: 30 Total: 45
Block: 8 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 30 Seek: 80 Rotate:190 Transfer: 30 Total: 300
TOTALS Seek: 80 Rotate:205 Transfer: 90 Total: 375
对7,30,8的请求与SSTF方法结果相同。
SATF明显优于SSTF的请求：7,6,24
ostep-homework-master\file-disks> python disk.py -a 7,6,24 -p SATF -G
REQUESTS ['7', '6', '24']
Block: 7 Seek: 0 Rotate: 15 Transfer: 30 Total: 45
Block: 24 Seek: 80 Rotate: 40 Transfer: 30 Total: 150
Block: 6 Seek: 80 Rotate: 70 Transfer: 30 Total: 180
TOTALS Seek:160 Rotate:125 Transfer: 90 Total: 375
ostep-homework-master\file-disks> python disk.py -a 7,6,24 -p SSTF -G
REQUESTS ['7', '6', '24']
Block: 7 Seek: 0 Rotate: 15 Transfer: 30 Total: 45
Block: 6 Seek: 0 Rotate:300 Transfer: 30 Total: 330
Block: 24 Seek: 80 Rotate: 70 Transfer: 30 Total: 180
TOTALS Seek: 80 Rotate:385 Transfer: 90 Total: 555
出现差异的原因是同一磁道的旋转时间太长，大于先去其它磁道读取再回来的时间。
- 问题 6 答案
因为磁盘寻道的同时也在旋转，因此到了下一个磁道时已经超过应该读取的位置了，只能额外转一圈。
ostep-homework-master\file-disks> python disk.py -a 10,11,12,13 -o 2 -G
REQUESTS ['10', '11', '12', '13']
Block: 10 Seek: 0 Rotate:105 Transfer: 30 Total: 135
Block: 11 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 12 Seek: 40 Rotate: 20 Transfer: 30 Total: 90
Block: 13 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
TOTALS Seek: 40 Rotate:125 Transfer:120 Total: 285
ostep-homework-master\file-disks> python disk.py -a 10,11,12,13 -S 2 -o 1 -G
REQUESTS ['10', '11', '12', '13']
Block: 10 Seek: 0 Rotate:105 Transfer: 30 Total: 135
Block: 11 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 12 Seek: 20 Rotate: 10 Transfer: 30 Total: 60
Block: 13 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
TOTALS Seek: 20 Rotate:115 Transfer:120 Total: 255
ostep-homework-master\file-disks> python disk.py -a 10,11,12,13 -S 4 -o 1 -G
REQUESTS ['10', '11', '12', '13']
Block: 10 Seek: 0 Rotate:105 Transfer: 30 Total: 135
Block: 11 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 12 Seek: 10 Rotate: 20 Transfer: 30 Total: 60
Block: 13 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
TOTALS Seek: 10 Rotate:125 Transfer:120 Total: 255
实际的偏斜距离要大于单个寻道时间磁盘旋转的距离。
- 问题 7 答案
ostep-homework-master\file-disks> python disk.py -z 10,20,30 -a -1 -A 5,-1,0 -s 1 -G
REQUESTS [7, 45, 41, 13, 26]
Block: 7 Seek: 0 Rotate:245 Transfer: 10 Total: 255
Block: 45 Seek: 40 Rotate: 55 Transfer: 20 Total: 115
Block: 41 Seek: 0 Rotate:260 Transfer: 20 Total: 280
Block: 13 Seek: 40 Rotate:335 Transfer: 10 Total: 385
Block: 26 Seek: 0 Rotate:120 Transfer: 10 Total: 130
TOTALS Seek: 80 Rotate:1015 Transfer: 70 Total:1165
ostep-homework-master\file-disks> python disk.py -z 10,20,30 -a -1 -A 5,-1,0 -s 2 -G
REQUESTS [51, 51, 3, 4, 45]
Block: 51 Seek: 40 Rotate: 70 Transfer: 20 Total: 130
Block: 51 Seek: 0 Rotate:340 Transfer: 20 Total: 360
Block: 3 Seek: 40 Rotate: 35 Transfer: 10 Total: 85
Block: 4 Seek: 0 Rotate: 0 Transfer: 10 Total: 10
Block: 45 Seek: 40 Rotate: 85 Transfer: 20 Total: 145
TOTALS Seek:120 Rotate:530 Transfer: 80 Total: 730
单位时间扇区数: 内圈1/30，中圈1/20，外圈1/10.
- 问题 8 答案
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 1 -c
TOTALS Seek:20960 Rotate:169165 Transfer:30000 Total:220125
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 5 -c
TOTALS Seek:11280 Rotate:44955 Transfer:30000 Total:86235
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 10 -c
TOTALS Seek:8080 Rotate:26555 Transfer:30000 Total:64635
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 25 -c
TOTALS Seek:3440 Rotate:11395 Transfer:30000 Total:44835
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 50 -c
TOTALS Seek:1680 Rotate:7035 Transfer:30000 Total:38715
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 75 -c
TOTALS Seek:1760 Rotate:6595 Transfer:30000 Total:38355
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 100 -c
TOTALS Seek:1440 Rotate:5835 Transfer:30000 Total:37275
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 200 -c
TOTALS Seek:960 Rotate:4515 Transfer:30000 Total:35475
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 300 -c
TOTALS Seek:1120 Rotate:4355 Transfer:30000 Total:35475
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 500 -c
TOTALS Seek:1280 Rotate:4195 Transfer:30000 Total:35475
ostep-homework-master\file-disks> python disk.py -A 1000,-1,0 -p SATF -w 1000 -c
TOTALS Seek:1520 Rotate:3955 Transfer:30000 Total:35475
- 问题 9 答案
导致第一个请求的扇区饥饿的序列：
ostep-homework-master\file-disks> python disk.py -a 24,7,8,9,10,11,0,1,2,3,4,5,6 -p SATF -G
REQUESTS ['24', '7', '8', '9', '10', '11', '0', '1', '2', '3', '4', '5', '6']
Block: 7 Seek: 0 Rotate: 15 Transfer: 30 Total: 45
Block: 8 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 9 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 10 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 11 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 0 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 1 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 2 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 3 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 4 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 5 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 6 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 24 Seek: 80 Rotate: 70 Transfer: 30 Total: 180
TOTALS Seek: 80 Rotate: 85 Transfer:390 Total: 555
使用有界的SATF方法：
ostep-homework-master\file-disks> python disk.py -a 24,7,8,9,10,11,0,1,2,3,4,5,6 -p BSATF -w 4 -G
REQUESTS ['24', '7', '8', '9', '10', '11', '0', '1', '2', '3', '4', '5', '6']
Block: 7 Seek: 0 Rotate: 15 Transfer: 30 Total: 45
Block: 8 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 9 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 24 Seek: 80 Rotate:340 Transfer: 30 Total: 450
Block: 10 Seek: 80 Rotate:190 Transfer: 30 Total: 300
Block: 11 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 0 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 1 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 2 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 3 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 4 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 5 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 6 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
TOTALS Seek:160 Rotate:545 Transfer:390 Total:1095
可以解决饥饿问题，但是IO时间增加了。
应该设置合适的窗口大小，在性能和避免饥饿之间平衡。
- 问题 10 答案
全局最优的调度比贪婪方法好的例子 10,11,0,21,1,2,3,4,5,6
全局最优由FIFO方法，手动指定全局调度结果。
ostep-homework-master\file-disks> python disk.py -a 10,11,0,21,1,2,3,4,5,6 -p SATF -G
REQUESTS ['10', '11', '0', '21', '1', '2', '3', '4', '5', '6']
Block: 21 Seek: 40 Rotate: 35 Transfer: 30 Total: 105
Block: 0 Seek: 40 Rotate: 20 Transfer: 30 Total: 90
Block: 1 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 2 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 3 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 4 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 5 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 6 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 10 Seek: 0 Rotate: 90 Transfer: 30 Total: 120
Block: 11 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
TOTALS Seek: 80 Rotate:145 Transfer:300 Total: 525
ostep-homework-master\file-disks> python disk.py -a 10,11,0,1,2,3,4,5,6,21 -G
REQUESTS ['10', '11', '0', '1', '2', '3', '4', '5', '6', '21']
Block: 10 Seek: 0 Rotate:105 Transfer: 30 Total: 135
Block: 11 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 0 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 1 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 2 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 3 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 4 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 5 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 6 Seek: 0 Rotate: 0 Transfer: 30 Total: 30
Block: 21 Seek: 40 Rotate: 20 Transfer: 30 Total: 90
TOTALS Seek: 40 Rotate:125 Transfer:300 Total: 465