Underrust: What is the cost of Mutex, RwLock and AtomicPtr?
With many concurrent readers and a single occasional writer, which mutual exclusion primitive should you use? Let's look at the assembly to find out.
This is the personal blog of Graham King. I write mostly about software engineering, and occasionally about society. I am also on Mastodon and Github.
All posts by date
2025
Underrust: How does u128 work on a 64-bit processor?
Wherein our hero learns the arcane secrets of the u128 sword in the depths of the Underrust.
Rust HashMap notes
Raw notes on Rust's HashMap design and implementation
CPU Performance Optimization notes
Raw notes on CPU optimization
Transparent Software
A software system is transparent when you can look at it and immediately understand what it is doing and how.
2024
Travels with ChatGPT
An overconfident genius personal assistant in my pocket
AI Hallucinations Are Often Reasonable Suggestions
Don't dismiss the statistically probable
Underrust: What does vec![0u8; 1024] really do?
How does Rust allocate a zeroed Vec and what does it cost?
The memory remains: Permanent memory with systemd and a Rust allocator
A Rust object that survives program restart thanks to Rust allocators, systemd's file descriptor store, and syscall memfd_create.
2022
Linux: What can you epoll?
On Linux what can you turn into a file descriptor and then monitor with epoll?
Underrust: Multiple Return Values
How does Rust return values, and does it make any difference to us programmers?
Overthinking Leetcode's Two Sum with SIMD
When is the linear scan Two Sum solution faster than a map? What if we use AVX-512 instructions?
Underrust: What is the cost of sync::Once?
In Rust, what is the performance cost of using sync::Once after the initial setup?
Underrust: Does it matter what type (u8, u32, ...) I use?
In Rust, how does using a different primitive type (u8, i32, u64, ...) change the generated assembly?
The Underrust: Rust's assembly output
Assembly: In all the world of the programmer, there is no more important output.
A very small Rust binary indeed
Can we make a Rust program that's as small as it's assembler equivalent?
A random number you already have: The stack address
Thanks to Address Space Layout Randomization you can use the address of a stack variable as a zero-cost random number.
Return Value Optimization in Rust
Rust avoids memory copies by optimizing return value placement.
Rust atomics on x86: How and why
On x86 it doesn't really matter what sync::atomic::Ordering you choose.
Rust is also C
Safety is boring, let's do pointer arithmetic.
epoll: The API that powers the modern internet
Linux's epoll API solved the C10K problem, enabling fast and afforable Internet services.
2021
Scripting Minecraft server with Python
Minecraft has an API. If you run your own server you can program it from Python.
Rust Performance 101 in 5 Minutes
Is your Rust program CPU bound? Here are the very first things you can do on Linux.
CPU silently disappointed with your choice of instruction ordering
An adventure in CPU out-of-order instruction execution.
Traits: Rust's unifying concept
Rust's traits are a single concept that unifies interfaces, abstract classes, mix-ins, operator overloading, contraints on generics, and more.
2020
A day in the life of a professional software engineer
Just a normal day reversing linked lists on the whiteboard.
Three things I wish I’d known learning Rust
It will take longer to learn than most languages, the standard library is small so you'll need dependencies, and a lot of behavior is in traits.
Quote of the day: A stirring speech
... because, at every new incident, your fortitude was to be called forth, and your courage exhibited; because danger and death surrounded it, and these you were to brave and overcome. For this was it a glorious, for this was it an honourable undertaking.
The simplest CLI that could possibly work
In Go, what's the simplest possible way to put all your ad-hoc tools in one place?
Collect and handle multiple errors in Go
In Go, how do you run several operations that might return an error, and return those errors at the end? Here's how I do it.
2019
A developer goes to a DevOps conference
Two days at PDX DevOpsDays, a gathering of system administrators who use version control, and write a lot of YAML.
2018
Reading MediaRecorder’s webm/opus output
Making like Theseus in the WEBM/MATROSKA/EBML audio maze
Javascript’s async/await and Promise in a few words
Unraveling the magic of async/await: From callbacks to linear code.
Growing software, in two tweets
Cultivating code: From seedling to flourishing software garden.
2017
What Made Maddy Run
Unveiling the hidden struggles behind a perfect facade.
Learn Better – book notes
Unlock your learning potential: Practical tips for mastering any skill.
2016
systemd socket activation in Go
"Unlock root-level ports without root privileges: A guide to systemd socket activation"
The Joy of systemd
Embracing the future: A quick guide to systemd for modern daemon management.
2015
How Ada Lovelace solved problems
Ada Lovelace: Debugging by horseback since 1843.
Facebook’s code quality problem
"Move fast and break things: A cautionary tale from Facebook's code quality woes."
Decrypt your HTTPS traffic with mitmproxy
Decrypt, inspect, and debug HTTPS traffic with mitmproxy and iptables.
OSCON 2015: Impressions
OSCON: Where open source meets commerce and connections bloom.
GopherCon 2015: Favorite talks
"GopherCon 2015: Where infrastructure meets innovation and inclusivity"
We are Equality
Equality in the digital realm: Where technology levels the playing field.
Building shared libraries in Go: Part 2
Seamlessly bridging Go and C++: A practical guide to shared libraries.
Building shared libraries in Go: Part 1
Unleash Go's power: Create shared libraries for seamless language integration!
How memory is allocated
Diving deep: How to allocate memory without malloc in Linux assembly.
Go: Slice search vs map lookup
Maps vs. slices: Choose wisely for optimal performance.
Software engineering practices
Timeless wisdom for crafting better code: Essential software engineering practices.
How I read job postings
Decoding the programmer's job hunt: It's simpler than you think!
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