作者polomoss (小泽)
看板Grad-ProbAsk
标题[理工] [OS]-95台大
时间Mon Jan 18 23:59:11 2010
10.(5%)In operating systems, the scheduler performs a rescheduling when
current process requests an I/O, the time slice assigned to current process
is exhausted, the current process yields, or higher-priority processes
arrive. On every rescheduling, it will take time for the kernel to perform
context switch. Is it possible for a round-robin scheduler with a
100-millisecond time slices to spend over half its time in the OS context
switch code? Assume that it take the OS 1 millisecond to context switch the
CPU. Please justify your answer and give an example.
这题看不懂,求强者帮忙解惑
Given a computer system with a 52-bit virtual address, 4 KB pages, and 4
bytes per page entry. Suppose that the maximum physical memory size is 512
GB, and the system is byte-addressable. Let paging be implemented for the
system. What is the number of bits for physical addresses, and what is the
maximum number of pages for a process?
52-bit virtual address → 252/4KB → 240 pages for a process.
想问答案b为什麽是这样算~? 要求process占用的page个数
不是应该从phisical memory着手吗?
谢谢
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