administrivia

Q&A Monday, 11:30-12:20, 560

final exam Wednesday, 2:30, here

everything: lectures/sections/exercises/hws/readings

including today’s reading, minus Rust/JavaScript

today’s plan

what have we been doing for the last 10 weeks?

course goals

programming: C/C++

systems: talk to the OS for fs/net/proc/thread/…

tools: make, gcc, gdb, valgrind, nc, …

coding discipline

deal with uncertainty: debugging, learning, communication

curiosity

C: a high-level assembler

designed to write OSes (Unix)

abstractions: fixed-width integers, pointers, structs, …

control: compilers won’t generate code you didn’t write

“easy” to understand & tune performance

trade-off: easy to shoot oneself in the foot

C++: a better C (or not)

tries to keep the good/low-level part

higher-level abstractions

encapsulation: class (members/methods), namespace

polymorphism: virtual functions & templates

(compare to function pointers & macros)

examples: std::string vs char *, std::thread vs pthreads

programming beyond C/C++

performance vs safety: garbage collection, big integers?

choose language(s) that work best for your applications

real-world concerns: easy to hire? fit existing code bases?

keep an open mind: Rust, Go, Java, Racket, OCaml, Haskell, …

systems overview

this course: programming interface to the kernel

memory management, file systems, networking, threading

general principles

systems: abstractions

naming: filenames, DNS, IP

file descriptors

systems: virtualization

virtual address: mmap, processes

virtual processor: processes/threads

example: valgrind

systems: layering

example: FILE *, fd, kernel, disk

example: HTTP, TCP, IP, link layer

caching (fsync)

interface (zero-copying)

tools: make our life easier

segfaults: much worse when bugs don’t segfault

valgrind: find memory leaks without it?

how to build tools & design tool-friendly systems/languages

example: Linux kernel

example: g vs ms

coding discipline

know what (not) to use

less error-prone constructs

performance trade-off

example: new/delete vs unique_ptr

communication

programming is not everything

in: reading books/google/stackoverflow/manpages

out: giving talks & writing

future courses

341: programming langauges: principles & foundations

451: operating systems: lowest level of software stack

452: distributed systems: time, failure, coordination

grad courses: 505, 550, 551, 552

beyond 333

my humble advice

“perfect is the enemy of good”: end-to-end first; then improve

get your hands dirty (e.g., big-endian hands-on, learn Go in 452)

know yourself: what you like & you are good at

that’s it

congratulations & good luck on the exam(s)!

big thanks to Sunjay, Renshu, Josue, Edward!

stay in touch: drop by 560, grab lunch, emails