Homeworks

Each chapter has some questions at the end; we call these “homeworks”, because you should do the “work” at your “home”. Make sense? It’s one of the innovations of this book.

Homeworks can be used to solidify your knowledge of the material in each of the chapters. Many homeworks are based on running a simulator, which mimic some aspect of an operating system. For example, a disk scheduling simulator could be useful in understanding how different disk scheduling algorithms work. Some other homeworks are just short programming exercises, allowing you to explore how real systems work.

For the simulators, the basic idea is simple: each of the simulators below let you both generate problems and obtain solutions for an infinite number of problems. Different random seeds can usually be used to generate different problems; using the -c flag computes the answers for you (presumably after you have tried to compute them yourself!).

Each homework included below has a README file that explains what to do. Previously, this material had been included in the chapters themselves, but that was making the book too long. Now, all that is left in the book are the questions you might want to answer with the simulator; the details on how to run code are all in the README.

Thus, your task: read a chapter, look at the questions at the end of the chapter, and try to answer them by doing the homework. Some require a simulator (written in Python); those are available by below. Some others require you to write some code. At this point, reading the relevant README is a good idea. Still others require some other stuff, like writing C code to accomplish some task.

To use these, the best thing to do is to clone the homeworks. For example:

prompt> git clone https://github.com/remzi-arpacidusseau/ostep-homework/
prompt> cd file-disks
prompt> ./disk.py -h

Introduction

Chapter	What To Do
Introduction	No homework (yet)

Virtualization

Chapter	What To Do
Abstraction: Processes	Run process-run.py
Process API	Run fork.py and write some code
Direct Execution	Write some code
Scheduling Basics	Run scheduler.py
MLFQ Scheduling	Run mlfq.py
Lottery Scheduling	Run lottery.py
Multiprocessor Scheduling	Run multi.py
Abstraction: Address Spaces	Write some code
VM API	Write some code
Relocation	Run relocation.py
Segmentation	Run segmentation.py
Free Space	Run malloc.py
Paging	Run paging-linear-translate.py
TLBs	Write some code
Multi-level Paging	Run paging-multilevel-translate.py
Paging Mechanism	Run mem.c
Paging Policy	Run paging-policy.py
Complete VM	No homework (yet)

Concurrency

Chapter	What To Do
Threads Intro	Run x86.py
Thread API	Run some C code
Locks	Run x86.py
Lock Usage	Write some code
Condition Variables	Run some C code
Semaphores	Read and write some code
Concurrency Bugs	Run some C code
Event-based Concurrency	Write some code

Persistence

Chapter	What To Do
I/O Devices	No homework (yet)
Hard Disk Drives	Run disk.py
RAID	Run raid.py
FS Intro	Write some code
FS Implementation	Run vsfs.py
Fast File System	Run ffs.py
Crash Consistency and Journaling	Run fsck.py
Log-Structured File Systems	Run lfs.py
Solid-State Disk Drives	Run ssd.py
Data Integrity	Run checksum.py and Write some code
Distributed Intro	Write some code
NFS	Write some analysis code
AFS	Run afs.py