C++ and Beyond 2012: Herb Sutter - atomic Weapons 2 of 2
Why Hacker News recommends it
HN recommends it as an in-depth, practical introduction to atomics and weak versus strong memory ordering, relevant to ARM and Rust as well as C++.
What it is
Part two of Herb Sutter's C++ and Beyond 2012 session on atomic weapons, a deep dive into the C++ memory model, atomics, memory ordering, and hardware behavior. It ends with the modern meaning of volatile.
Recommended by 2 HN commenters across 2 different months, 2019 to 2024.
What Hacker News said
Strong rec NobodyNada · 2023-11 · on “C++ Memory Model: Migrating from x86 to ARM”
For a more in depth introduction to the topic with a lot of practical code examples, I highly recommend Herb Sutter’s excellent talk: Part 1 [LINK] Part 2 [this video]
Strong rec chc4 · 2024-08 · on “Rust Atomics and Locks (2023)”
"Is Parallel Programming Hard, And, If So, What Can You Do About It?" is one of the best books about atomics and concurrency, and my #2 recommendation. [LINK] My #1 actually isn't a book at all, but the two "atomic Weapons" talks by Herb Sutter, which are extremely good. [LINK] [this video]
Cites oconnor663 · 2019-05 · on “Ways to break your systems code using volatile (2010)”
Herb Sutter's (three hour long!) Atomic Weapons talk goes over the modern meaning of volatile towards the end: [this video]
Cites NobodyNada · 2021-10 · on “Ask HN: What does one look for in a laptop these days?”
It’s true that ARM alone isn’t the reason for the M1’s performance, but it’s definitely a significant factor. x86 is old — modern x86 chips are still backwards-compatible with the original 8086 from 1978 — and it’s stuck with plenty of design decisions that might have been the correct choice sometime within the past 45 years but no longer today. Whereas the M1 only implements AArch64, a complete redesign of the ARM architecture from 2012, so it doesn’t have to deal with legacy architectural baggage. (We’ve known x86 was the wrong design since the 80’s — hence why there’s no Intel chips in smartphones — but it hasn’t been realistic for anybody except Apple to spend 10 years and billions of do
Cites cowtools · 2022-07 · on “Ask HN: Can competitors catch up to Apple Silicon?”
I would imagine that any implementation of x86 would have to bear the weight of reverse-compatibility. With reverse comparability, the bad design decisions just compound, for example complicated stuff like memory synchronization [this video]
Cites mlindner · 2023-01 · on “Rust Atomics and Locks: Low-Level Concurrency in Practice”
The book, especially chapter 7 seems to say several things completely opposite to what Herb Sutter did in his famous talk a number of years ago. In the book: > This means that on ARM64, sequentially consistent operations are exactly as cheap as acquire and release operations. Or, rather, that ARM64 Acquire, Release, and AcqRel operations are as expensive as SeqCst. Unlike x86-64, however, Relaxed operations are relatively cheap, as they don’t result in stronger ordering guarantees than necessary. However in Herb Sutter's talk (specifically the second half here: [this video] ) he says that ARMv8 Acquire/Release/AcqRel operations are cheaper than SeqCst. This book seems to claim that x64 is somehow