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Systems & Performance

The most popular blog posts about systems & performance on Hacker News. 518 posts.

2026
302

Dissecting Apple's Sparse Image Format (ASIF)

At WWDC 2025, Apple announced macOS 26 Tahoe. One of the new features in macOS Tahoe is a new disk image format: ASIF. Designed for use with virtual machines (its documentation lives under the Virtualization framework), ASIF takes a lot of inspiration from existing virtual disk formats. Practically, that means it’s…

307

The lost malloc()

Prompted by another project idea that popped into my mind, I did some Unix archaeology and looked at the original sources . This is the most fun I've ever had reading someone else's code - probably due to the historical significance. But also because of how delightfully approachable it was, compared to modern…

308

Surprising economics of load-balanced systems

I have a system with c servers, each of which can only handle a single concurrent request, and has no internal queuing. The servers sit behind a load balancer, which contains an infinite queue. An unlimited number of clients offer c * 0.8 requests per second to the load balancer on average. In other words, we increase…

309

The Fil-C Optimized Calling Convention

Fil-C achieves memory safety even for programs that behave adversarially. That includes casting function pointers to the wrong signature and then calling them, exporting a function with one signature in one module and then importing it with a different signature in another, or even exporting a symbol as a function in…

313

Understanding the Go Runtime: The Scheduler

In the previous article we explored how Go’s memory allocator manages heap memory — grabbing large arenas from the OS, dividing them into spans and size classes, and using a three-level hierarchy (mcache, mcentral, mheap) to make most allocations lock-free. A key detail was that each P (processor) gets its own memory…

317

OpenBSD on Motorola 88000 Processors

Many people know, or have heard of, the Motorola 68000 architecture. These processors have been used in many machines: in the first generations of Apple Macintosh computers, in the ever-rivals Amiga and Atari ST home computers, in many workstations built by Sun , HP and NeXT (to name only a few), but also in many…

319

Systems that no one will test

(this post figured on HNews here) This happened to me in 2020, and it has been on my mind again lately. During the worst of the pandemic, I found a vulnerability in a system that gave me access to the Brazilian federal system, and with that access I was able to retrieve information on any

320

GC and Exceptions in Wasmtime

The Wasm GC and exceptions proposals are both enabled by default in today’sWasmtime 47 release! We are excited to help bring more languages to WebAssemblyand everywhere that Wasmtime runs. Getting to this point involved large Wasmtimecha...

328

Win16 Memory Management

This is a kind of knowledge base article which resulted from attempts to understand exactly how memory management works in 16-bit Windows. It is not exactly undocumented, but it is also not well documented; even before Windows 3.0 appeared, the assumption was that essentially all application developers were going to…