In-class notes for 09/28/2020 (CS 273 (OS), Fall 2020)

In-class notes for 09/28/2020

CS 273 (OS), Fall 2020

Exam Wednesday - in-person in RNS 310 (except for remote students)
- 45 minutes
- topics below
- No computers, technology, book, notes, etc.
- Seating will be assigned; papers will be upside down on desk (keep upside down until I give the signal)
- Turn in by leaving upside down on desk or box at front of room.
- Wash in, wash out

To study for quiz

General items

Terms: operating system, process, system call, kernel, shell, user vs system portions of a process, (Linux) signal
- Understand these terms enough to be able to read and write about them.
Four main services of an operating system
- Process management
- Memory management
- Devices
- File system
Process states -- be ready to discuss how OS services (e.g., I/O operations, scheduling, system calls such as wait(), interrupt handling) relate to the process-state diagram

C language: Lab 1 and HW 2

System calls
- General familiarity with behavior of most emphasized system calls:
  open(), read(), write(), close(), fork(), execve(), wait(), dup(), kill(), getpid().
  - Know arguments and return for fork(), execve(), wait()
  - Arguments/return would be provided if needed for the others
  - Relationship between open-file data structures and file descriptor table
  - Process diagrams - fork/exec/wait, redirection of standard input/standard output (only)
- Process diagrams, including fork/execve/wait, redirection of output, pipelines, etc.
- Algorithms and data structures for processes:
  - Process table -- Array of process table entries; each PTE contains information relevant to a particular process. Have a general familiarity with type of information (see examples).
  - Interrupt vector
  - Algorithm for handling interrupts -- study these steps, and ask any questions on Piazza or on questions of the day for next class meeting.
- Programming with system calls: be prepared to write segments of C code that may use any of the following system calls: fork(), execve(), wait()
  - References: ~rab/os/mopen.c, ~rab/os/forkeg.c, and steps 2-4 of Strategy for developing a shell
  - Arguments - see man pages for system calls fork, execve, wait
IPC strategies
- Busy wait, TSL, ______
- Dining philosophers example
- Race conditions (correct behavior depends on timing) and four conditions for correct IPC - understand each
  - Mutual exclusion; bounded wait; independence of speed; progress
  - Know them - be able to describe them and apply them
- Semaphores, monitors, message passing:
  - Data structures and primitives; see also class notes on these IPC strategies
  - Review the shared data structure in-class exercises (semaphores, monitors, message passing)
  - Review text's producer/consumer examples
- Usage contexts for each of these IPC strategies, e.g., monitors are implemented within a programming language
Race conditions: definition; locating race conditions.
pthreads programming -
- Reading knowledge (e.g., ~rab/os/pthreads.c)
- Coding similar to homework or modifications of given code.

Scheduling

Memory management overview

Technical challenge? Effect on the programmer? Effect on user?

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