Illuminating the processor core with LLVM-mca
Originally posted as Fast TotW #99 on September 29, 2025 By Chris Kennelly Updated 2025-10-07 Quicklink: abseil.io/fast/99 The RISC versus CISC debate ended in a draw: Modern processors decompose instructions into micro-ops handled by backend execution units. Understanding how instructions are executed by these units can give us insights on optimizing key functions that are […]
AI and the ironies of automation – Part 2
In the previous post, we discussed several observations, Lisanne Bainbridge made in her much-noticed paper “The ironies of automation”, she published in 1983 and what they mean for the current “white-collar” work automation attempts leveraging LLMs and AI agents based on LLMs, still requiring humans in the loop. We stopped at the end of the […]
Vacuum Is a Lie: About Your Indexes
There is common misconception that troubles most developers using PostgreSQL: tune VACUUM or run VACUUM, and your database will stay healthy. Dead tuples will get cleaned up. Transaction IDs recycled. Space reclaimed. Your database will live happily ever after. But there are couple of dirty “secrets” people are not aware of. First of them being […]
The Gorman Paradox: Where Are All the AI-Generated Apps?
In 1950, while discussing the recent wave of flying saucer reports over lunch with colleagues at Los Alamos National Laboratory in New Mexico, physicist Enrico Fermi asked a simple question. There are hundreds of billions of stars in our Milky Way galaxy, and – presumed at the time – a significant percentage have Earth-like habitable […]
Efficient Basic Coding for the ZX Spectrum
[Click here to read this in English ] Éste es el primero de una serie de artículos que explican los fundamentos de la (in)eficiencia de los programas en BASIC puro para el ZX Spectrum: I. Sobre los números de línea II. Sobre las variables III. Sobre las expresiones IV. Funcionalidades diversas y medida del tiempo […]
Shai-Hulud compromised a dev machine and raided GitHub org access: a post-mortem
On November 25th, 2025, we were on a routine Slack huddle debugging a production issue when we noticed something strange: a PR in one of our internal repos was suddenly closed, showed zero changes, and had a single commit from… Linus Torvalds? The commit message was just “init.” Within seconds, our #git Slack channel exploded […]
Surface Tension of Software
How systems hold their shape through constraint, and why integrity emerges from what you make impossible If you press your finger against water, it pushes back. That invisible resistance, surface tension, keeps the liquid whole even when disturbed. Good software has something like it. Some systems hold together when you change them; others leak at […]
Compiler Engineering in Practice
“Compiler Engineering in Practice” is a blog series intended to pass on wisdom that seemingly every seasoned compiler developer knows, but is not systematically written down in any textbook or online resource. Some (but not much) prior experience with compilers is needed. What is a compiler? The first and most important question is “what is […]
Lean Theorem Prover Mathlib
Mathlib is a user maintained library for the Lean theorem prover. It contains both programming infrastructure and mathematics, as well as tactics that use the former and allow to develop the latter. Installation You can find detailed instructions to install Lean, mathlib, and supporting tools on our website. Alternatively, click on one of the buttons […]
If a Meta AI model can read a brain-wide signal, why wouldn’t the brain?
Did you know migratory birds and sea turtles are able to navigate using the Earth’s magnetic field? It’s called magnetoreception. Basically, being able to navigate was evolutionarily advantageous, so life evolved ways to feel the Earth’s magnetic field. A LOT of ways. Like a shocking amount of ways. Here’s a few examples: Magnetotactic bacteria – […]