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11/13 os作業
名稱	11/6 os作業
日期	11/13
課程名稱	作業系統
指導教師	劉艾華

1.
I think the suitable situation to use message passing is when you are going to exchange smaller amounts of data. The benefits of using message passing are it is easier to implement than shared memory for inter-computer communication. Message can be exchange directly or indirectly through mailbox. Programmer has a complete control, but if you use shared memory, the benefits are it allows maximum speed and convenience of communication. You could be sure about the location you’re writing, because you won’t write to the same location simultaneously.
The disadvantages by using shared memory is there might be a problem between the areas of protection and synchronization in the processes sharing memory, while the disadvantage in using message passing is programmer have to do everything. It might be slower than shared-memory.

2.
What is “system calls?” Please specify the functions and the purposes of a system call in a computer system.
System call provide the interface between a running program and the operating system.
System call is available to the operating system used by the application function call. Usually the system call will cause the system transferred to the program executed in kernel mode. System call is to allow the operating system to make smooth.

3(1).

Used to modify a copy of the source code of the OS and have it re-compiled.
Used to create tables and modules from a precompiled library. The needed modules are linked together to form the generated OS.

3.(2)
The size and generality of the generated system and the ease of modification as the hardware configuratio

更新日期：2015/11/13 上午 02:00:52