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Systems & Performance

The most popular blog posts about systems & performance on Hacker News. 543 posts.

2025
31

Why is my CPU usage always 100%?

If you’re new to this series, I’ve been documenting the process I went through upgrading my old PXA166-based Chumby 8’s 2.6.28 Linux kernel to a modern 6.x version. Here are links to parts 1 , 2 , 3 , 4 , 5 , 6 , 7 , and 8 . At this point in the project, all of the main hardware peripherals were working great. I…

34

Memory Integrity Enforcement

Memory Integrity Enforcement (MIE) is the culmination of an unprecedented design and engineering effort spanning half a decade that combines the unique strengths of Apple silicon hardware with our advanced operating system security to provide industry-first, always-on memory safety protection across our devices …

42

3,200% CPU Utilization

A while back my machine was so messed up that I could barely ssh onto it. 3,200% CPU utilization - all 32 cores on the host were fully utilized! Compare that to my last bug where it only used 1 core, 100% Fortunately, it was using Java 17 runtime which...

43

Apple’s Darwin OS and XNU Kernel Deep Dive

A deep dive into Apple’s Darwin OS and XNU kernel architecture, tracing its evolution from Mach and BSD roots to powering macOS, iOS, and Apple Silicon. This post explores the hybrid kernel’s design, its adaptation to new hardware and security paradigms, and why XNU remains a uniquely resilient and scalable foundation…

48

Futurelock: A subtle risk in async Rust

This RFD describes futurelock : a type of deadlock where a resource owned by Future A is required for another Future B to proceed, while the Task responsible for both Futures is no longer polling A . Futurelock is a particularly subtle risk in writing asynchronous Rust.

52

%CPU utilization is a lie

I deal with a lot of servers at work, and one thing everyone wants to know about their servers is how close they are to being at max utilization. It should be easy, right? Just pull up top or another system monitor tool, look at network, memory and CPU utilization, and whichever one is the highest tells you how close…

54

A Love Letter to FreeBSD

I’m still the new person here, learning your ways, stumbling over the occasional quirk, smiling when I find the small touches that make you different. You remind me of what computing felt like before the noise. Before hype cycles and performance theatre. Before every tool needed a plugin system and a logo. You are…

56

Jepsen: NATS 2.12.1

NATS is a popular streaming system. Producers publish messages to streams , and consumers subscribe to those streams, fetching messages from them. Regular NATS streams are allowed to drop messages. However, NATS has a subsystem called JetStream , which uses the Raft consensus algorithm to replicate data among nodes…

59

The Future Is Niri

The worst "street-cred" I have is that I've been using tiling window managers for thirty-five percent of my life: five years with Sway and two...