Re: [理工] OS-file system
※ 引述《x3795566 (冀憶)》之銘言：
: 以下為題目
: A disk has 4000 cylinders, each with 8 tracks of 512 blocks.
: A seek takes 1 msec per cylinder moved.
: If no attempt is made to put the blocks of a file close to each other, two
: blocks that are logically consecutive
: (i.e., follow one another in the file) will require an average seek, which
: takes 5 msec.
5 msec + (10 msec + 0.02 msec) = 15.02 msec(access time per block)
15.02 msec * 100 = 1.502 sec (100 blocks access time)
: If, however, the operating system makes an attempt to cluster related blocks
: , the mean interblock distance can be reduced to 2 cylinders and the seek
: time reduced to 100 microsec. How long does it take to read a 100 block file
: in both cases, if the rotational latency is 10 msec and the transfer time
: is 20 microsec per block?
(0.1 msec * 2) + (10 msec + 0.02 msec) = 10.22 msec (access time per block)
10.22 msec * 100 = 1.022 sec (100 blocks access time)
: 我看超久的還是不太懂怎麼寫 冏rz
: 希望有高手可以解答
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◆ From: 140.113.235.115
※ 編輯: svanavs 來自: 140.113.235.115 (06/08 14:51)
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06/09 00:43, , 1F
06/09 00:43, 1F
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