Re: [理工] [ OS ]-中山95
※ 引述《KarmaPolice (Karma Police)》之銘言：
: 4. Assume we have a demand-paged memory. The page table is held in registers.
: It takes 8 milliseconds to service a page fault if an empty page is available
: or the replaced page is not modified, and 20 milliseconds if the replaced page
: is modified. Memory access time is 100 nanoseconds. Assume that the page to be
: replaced is modified 70 percent of the time. What is the maximum acceptable
: page-fault rate for an effective access time of no more than 200 nanoseconds?
: 這題想請教一下該如何解?
: 我解出來的答案 讓我覺得有點離譜 想問問大家都是算多少?
EAT=(1-p)*100ns + p * (0.3*8ms+0.7*20ms)
=0.1ms-0.1ms*p+p*16.4ms
=0.1ms+(16.3ms)*p
and EAT<200ns
故
16.3ms*p<200ns-100ns=0.1ms
=> p<0.1ms/16.3ms =0.6%
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