Re: [理工] [計組]-90台大-average access time
※ 引述《steven9374 (steven)》之銘言:
: Virtual memory is often implemented by demand-page.
: Consider an operating system with on-demand paging
: over a single-level page table,where the page table
: of each process always resides in the memory.
: Suspose that the TLB access time,the memory access time,
: and the acerage page-fault service time are 20ns,100ns,25ms,
: respectively.Let the hit ratio of TLB and the page fault
: rate be 98% and 0.0001%,respectively.What is the effective
: access time?
: 答案寫=0.98*(20+100)+0.02*(20+100+100)*0.999999+
: 0.02*0.000001*(25+100+25000000)=122.5ns
: 後面實在看不太懂...
: 請求板上大大的教教小弟我
TLB(20)
↙ ↘
Hit(98%) Miss(2%)
↙ ↘
MEM(100) Page Table(100)
↙ ↘
Hit(99.9999%) Miss(0.0001%)
↙ ↘
MEM(100) Page Fault(25000000)
20 + 0.98*100 + 0.02*[ 100 + 99.999%*100 + 0.0001%*25000000 ] = 122.5ns
^^^^^^^=1
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 140.113.207.117
※ 編輯: bennylu 來自: 140.113.207.117 (01/15 17:01)
推
01/15 17:19, , 1F
01/15 17:19, 1F
推
01/15 17:25, , 2F
01/15 17:25, 2F
討論串 (同標題文章)
本文引述了以下文章的的內容:
完整討論串 (本文為第 2 之 2 篇):