若有4个进程共享同一个程序段,而且每次最多允许3个进程进入该程序段,则信号量的变化范围是______。
What does the man say about the seminar
A. She has no desire to teach.
B. She will graduate after the man does.
C. She likes all her teachers equally.
D. She has no idea where graduation will be held.
考虑一个存于磁盘上的文件系统,其中的文件由大小为512B的块组成。假定每一个文件有一个文件目录项,该目录项包含该文件的名字、文件长度以及第一块(或第一索引块)和最后一块的位置,而且该目录项位于内存。对于索引结构文件,该目录项指明第一索引块,该索引块又依次指向511个文件块且有一指向下一索引块的指针。针对连续、链接、索引结构的每一种,要求: a.说明在这个系统中是如何实现逻辑地址到物理地址映射的; b.如果当前位于逻辑块10(即最后一次访问的块是逻辑块10)且访问逻辑块4,请说明必须从盘上读多少个物理块。
What does the man say about the seminar
A. He’s spent all his money.
B. After all he prefers his old one.
C. He hasn’t, found one large enough.
D. He hasn’t found a suitable one.