20191218 "Introduction to Information Security" ninth weekly summary

Learning content summary

This week once again review the von Neumann architecture as well as its core memory architecture; understanding constitute the framework of a computer system: ALU, CU and registers CPU, CPU and memory composed of hosts, virtual memory, and a host constituting process; once again experience the importance of computer science in the abstract; at the same time, learn some basic Linus operating instructions: rm (delete), (the current directory), .. (on a directory), mkdir (create documents), cd (change directory. ), ~ (Back Home), and so on; in addition, learning the absolute path (starting from the root directory) and a relative path (from the current directory); distinguishing device files and disk files (text and binary files); taught himself FCFS, SSTF, SCAN disk scheduling method, the bottom of the computer have a more understanding; in addition, the dual identity aware operating system (OS): the housekeeper and waiter. Though still retains the term batch, but in modern operating systems, it has not turned out as required human-computer interaction. In addition, also learned mapping between logical addresses and physical addresses, and both: address bindings. Learning the single region memory management and memory management partition, a partition management and learning in fixed partitions, dynamic partitioning method, to understand the dynamic zoning laws first match, the best match, worst match; at the same time learn paged memory management. CPU scheduling in understanding FIFS, SJN and polling method.

"Self is the craft" to continue the previous review mission, completed the fourth time to read the fifth chapter, to appreciate the powerful python library functions. C language, this week to review last week's string array pointer and learned, and learned global variables, static variables and functions.

Textbook learning and problem-solving process

In the learning process I had doubts scheduling method for scheduling method of the CPU and disk: Since the two are similar, the two are not there to do with it? By looking up information on the Internet, I learned that the common denominator is that both read a similar way, the algorithm has the same point, the difference is reflected in the success of CPU scheduling depends on the process of the following attributes: execution process executed by the CPU and I / O wait cycle composition.

Reference material

https://www.cnblogs.com/kexinxin/p/9939075.html

https://blog.csdn.net/jaster_wisdom/article/details/52345674

Code debugging and problem solving in the process

Last week, after learning the value of participation reference parameters, I do in class by the C programming language to try: just combine learning (custom) function, I tried to write a swap (swap) function, as shown below

And x and y found not exchanged.

Through access to information, I learned that this is the way subprogram call parameters parameter values in the Senate, and variable swap function of x, y is only a copy of the argument, its scope is limited to routine; To pass the child program (function) to solve this problem, need to use a pointer (that is, using a reference parameter change argument address), the problem is resolved