COIS 3320H Lecture 2: WEEK 2 LEC NOTES part 2

• School: Trent University
• Department: Computing & Information Systems
• Course: COIS 3320H
• Professor: Jacques Béland

Document Summary

Direct execution: running a process: what happens when you run a program, the os creates a process, the os: It allocates memory: creates a data structure to hold all of the attributes of the process, find the firsy instruction and runs the code. Loads the program: when the code is done, deallocates memory, removed the process from the active process table. Unless the os also limits the resources an application can use, it could consume the whole machine. This means keeping the overhead of virtualization ro a minimum. Ensure that it remains in control of the system. It must prevent misbehaving code form monopolizing resources. To do this, it must place restrictions on what a process can do and what a process has to ask permission to do. The (cid:396)esults of these (cid:396)e(cid:395)ui(cid:396)e(cid:373)e(cid:374)ts is (cid:862)use(cid:396) mode(cid:863) a(cid:374)d (cid:862)ke(cid:396)(cid:374)el mode(cid:863) User mode: a process can jump to instruction, access memory locations within its own pre-allocated.