Learning Objectives¶

Virtualization¶

A person who is learning about operating systems needs to be able to know that virtualization allows a single physical CPU to simulate the functionality of multiple virtual CPUs, which maximizes a machine's capacity in handling applications.

Introduction¶

• Map out the processes of the OS virtualizing resources and doing it efficiently
• Make a hardware design of the operating system

Processes¶

• State the steps an Operating System should take in order to run a program (or process).
• List and describe the typical APIs available across many modern operating systems.
• Explain the lifecycle of a process, delineating each state of a process and what causes a shift in the state.
• Identify the UNIX interface used to create a new process and define the Process Identifier and describe how it relates to this interface.
• Compare the UNIX interfaces: fork(), wait(), + exec() and outline the difference in how the parent and child processes are used in each interface.
• List and explain the interfaces and/or user privileges that can be used to control processes.

Direct Execution¶

• Trace the steps of a Limited Direct Execution
• Measure the estimated cost of a given system call
• Trace the steps of Context Switch code
• Measure the cost of context switch code using the lmbench tool

CPU Scheduling¶

• Develop a scheduling policy based on workloads and scheduling metric priorities
• Design any scheduling algorithm with jobs being run over a certain period of time
• Design an STCF scheduler with overlap between the CPU and the disk over a certain period of time

Memory Management¶

• Locate and fix memory issues in an operating system
• Get around the issues of fragmentation when memory is requested
• Come up with the best situational strategy for managing space in general

Segmentation¶

• Design address spaces before and after segmentation
• Avoid segmentation faults when referring to addresses
• Determine the segment that an address is in based on how that address was formed

Paging¶

• Avoid the problems of segmentation by virtualizing memory with pages
• Virtualize memory via paging with minimal space and time overheads
• Design the address translation process from the virtual address to the physical address

Swapping¶

• Swap space for the OS to move pages back and forth
• Write page-fault handler code
• Perform replacements and using high watermark and low watermark

Concurrency¶

A person who is learning about operating systems needs to be able to add features to an operating system so that multiple processes can be run at the same time

Threads¶

• Write and execute the code necessary to create threads
• Pass arguments to threads
• Address the issue of shared data through building support for synchronized primitives to support atomicity
• Build mechanisms to support the sleeping and waking interaction between processes

Locks¶

• Create and maintain an efficient lock
• Properly evaluate the efficacy of locks
• Implement a compare-and-swap and compare-and-exchange in an OS

Semaphores¶

• Build and initialize a semaphore
• Use a semaphore as a lock and an ordering mechanism
• Solve the bounded buffer problem with semaphores

Persistence¶

A person who is learning about operating systems needs to be able to know the parts of a computer that persists after shutdown and know how to handle failures in the operating system.

Input/Output Devices¶

• Decide whether to lower CPU overhead with interrupts depending on the operating system
• Decide whether to lower PIO overhead with Direct Memory Allocation depending on the operating system
• Design both methods of device communication, those being I/O instructions and memory-mapped I/O

Files and Dictionaries¶

• Make the correct system calls when trying to create, rename, remove, write to, read from, or get the metadata from a file
• Make the correct system calls when trying to create, read, or remove directories

File System Implementation¶

• Create an appropriate design of the overall on-disk organization of data in a Very Simple File System
• Calculate the location of that inode in the disk given an inode number
• Decide whether to use direct pointers, indirect pointers, or extents depending on the files being dealt with

Data Integrity and Protection¶

• Handle the latent sector error failure mode
• Handle the data corruption failure mode
• Choose the best checksum function given a data corruption failure mode and a data integrity budget

Security¶

A person who is learning security must be able to implement a basic security system that can prevent attacks from getting information on your consumers. Within the security section, users are able to learn key concepts and techniques required to model and top of the line security system for an OS.

Authentication¶

• Implement basic knowledge of agent, principal, credential, and object into an OS
• Implement and working authentication by using sensitivity and hashes as a basic concept
• Be able to label weakness of each hashing method within an OS

Access Control¶

• Make the correct decision on performing an operation based on a security policy and a request of that operation
• Implement a reference monitor correctly
• Given an access priority for an operating system, decide whether to use discretionary or mandatory access control

Cryptography¶

• Implement a basic cypher within your OS
• Maintain secrecy of the key for your cryptography
• Decide whether to use a private key or a public key given a certain scenario

Distributed System Security¶

• Determine in a list what websites are secure and insecure
• Create and secure a distributed system in multiple approaches

Advanced Programming¶

A person who is learning the fundamentals of operating systems should demonstrate mastery of the following programming skills in all of the necessary programming languages:

Programming¶

• Write short programs up to five hundred lines that have the following characteristics for the chosen programming language:
  • Has function and variable names that adhere to an industry-standard coding style for the chosen programming language.
  • All program components have descriptive comments that adhere to an industry-standard coding style.
  • Features a source code format that adheres to an industry-standard coding style for the chosen language.
  • Passes an automated test suite, written with an industry-standard framework for the chosen language, showing that it correctly implements the specification for the function or component.
  • Performs the specified operation in an efficient fashion, as determined through experiments that evaluate the components's performance in minutes, seconds, or milliseconds.
  • Features functions that correctly use the basic building blocks of the chosen programming language in a way that passes the function's test suite, works efficiently, and conveys the function's intended purpose.
  • Correctly performs file and console input and output, ensuring that all input and output is displayed and stored correctly, is not corrupted, and is processed efficiently.
  • Correctly simulates aspects of an operating system (e.g., process scheduling) through the use of a program.

Programming Tools¶

• Use a Docker and/or operating system-based programming environment that supports a recent version of the C, Go, and Python programming languages to complete these tasks while implementing a program of up to five hundred lines of code:
  • Install, upgrade, and use a recent version of the Python programming language environment to create, run, and debug a Python program with a terminal window, a text editor, and the Poetry package manager.
  • Install, upgrade, and use a recent version of the C programming language toolchain to create, run, test, and debug a C program through a terminal window and/or a text editor.
  • Install, upgrade, and use a recent version of the Go programming language environment to create, run, test, debug, and format a Go program through a terminal window and/or a text editor.
  • Leveraging plugins for workflow enhancement, use a text editor like VS Code to implement, test, debug, document, and manage the source code of a program in the C, Go, or Python programming languages.

Version Control¶

• Use the GitHub platform and the Git version control system in the following fashion:
  • Using SSH keys, clone a GitHub repository without error using either a command in a terminal window or an extension for Git integration in a text editor like VS Code.
  • Write short and descriptive commit messages that use the Conventional Commits standard explain the specific way in which a commit changes the source code and documentation in the GitHub repository.
  • Navigate reports produced by GitHub Actions so as to determine which aspects of a GitHub repository do and do not adhere to a project's specification, iteratively fixing broken components until the project works.
  • In either a team-based on individual context, use the GitHub Flow model to implement specific features in a branch of a GitHub repository and then merge that branch to the main one only after all the checks run by GitHub Actions pass as required and code reviews confirm the code's correctness. When modifying the source code of the OS-Sketch web site, use a preview build created by Netlify to survey the site's content and layout.
  • Create and discuss programming and technical writing issues with the GitHub Issue Tracker and the GitHub Discussion Forum, furnishing descriptive titles and problem descriptions that adhere to industry best practices and project templates.
  • Submit completed projects that pass all of the automated instructor-provided and industry-standard checks, as evidenced through the report of a passing build run in GitHub Actions.

Effective Learning¶

A person learning about operating systems will demonstrate mastery of the following technology-mediated learning skills:

• Follow a systematic process when using resources to implement C, Go, and Python programs:

  • After detecting an error in a program through the use of either automated or manual debugging, develop a satisfactory understanding of the problem's likely root cause and then search sites like Stack Overflow for potential solutions.
  • After evaluating suggested solutions to a programming problem that originate from sites like Stack Overflow, develop a way to fix an error in a program, try that approach, and then incrementally improve it.
  • Independently develop solutions to programming problems even if the specifical technical challenge that you face was not previously covered in a course session or as part of your prior review of technical content.

• Use Discord to effectively communicate about technology in the following fashion:

  • In the correct public channel, post a question that includes source code segments, screenshots, and a description of the steps taken in an attempt to document and then ultimately solve a problem.
  • Answer questions that were posted in a public channel, responding with source code segments, screenshots, and links to external references, pointing the person who asked the question in the right direction without solving the problem for them and limiting their opportunity to learn more about the topic in question.
  • By sharing the acquired knowledge or skill, how you can be contacted, and how you can help, offer to help others who may need to learn technical knowledge and skills in the field of operating systems that a learner has already mastered.

Improving Objectives¶

As Robert Talbert explains, a learning objective is clear when it is "clear from the students' perspective" and measurable when there is "some way to know whether the objective has been met" or "how far away the learner is from meeting it".¹ Do you see a way in which we can improve the learning objectives for the OS-Sketch site? If you do, then please participate in the OS Sketch community by sharing your ideas for improving them!