3481
Almost booting an iOS kernel in QEMU
I tried to boot an iOS 12 kernelcache in QEMU: I managed to get as far as IOKit startup before receiving a kernel panic. I learned a lot about how iOS boots up with this project.
Topics /
Systems & Performance
The most popular blog posts about systems & performance on Hacker News. 4,390 posts.
3482
Low-level x86 code compression for 64k intros
This is about the “secret ingredient” in my EXE packer kkrunchy, which was used in our (Farbrausch) 64k intros starting from “fr-030: Candytron”, and also in a lot of other …
3483
Upgrading my Chumby 8 kernel part 10: RTC
I’m going to start this post off with the obligatory list of links to the previous parts in the series if you’re new here and are interested in seeing the full story: 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , and 9 . This is the tale of how I upgraded my Chumby 8 to run a modern Linux kernel.
3484
MRI's Method Caches
One of MRI's big performance problems is that method cache expiry is global. That is, any time you make a change to any class anywhere, the entire VM's method caches get busted at the same time. This is why you'll frequently hear people saying that "calling Object#extend is bad".
3485
Optimized Go gzip/zip packages, 30-50% faster
I have worked on optimizing the standard library deflate function, and I am happy to announce revised gzip/zip packages, that on x64 is about 30-50% faster with slightly improved compression. Project: https://github.com/klauspost/compress All packages are drop-in replacements for the standard libraries, so you can use…
3486
3487
Progressive Locks: fast, upgradable read/write locks
Context A few years after I created the Elastic Binary Trees (ebtree) , I started to get some feedback from users who needed to use the...
3488
How many registers does an x86-64 CPU have?
x86 is back in the general programmer discourse, in part thanks to Apple’s M1 and Rosetta 2 . As such, I figured I’d do yet another x86-64 post.
3489
Don’t Be Afraid of RAID
I sense this sentiment on the internet that RAID is dangerous, that the likelihood of your RAID array failing during a rebuild is almost a certainty, because hard drives have become so large.
3490
Migrate Everything from Linux to BSD
As an operating system GNU/Linux has become a mess because of the fragmented nature of the project, the bloatware in the kernel, but mainly because of the manipulation by corporate interests. There exist several technical reasons for when a migration from GNU/Linux to BSD make sense, but this article isn't about that…
3491
Mtime comparison considered harmful
tl;dr: Rebuilding a target because its mtime is older than the mtimes of its dependencies, like `make` does, is very error prone. redo does...
3492
Effortless Performance Improvements in C++: std:unordered_map
This is the second post in the series about effortless performance improvements in C++. Check the first post to get the full story!
3493
Each socket should have two file descriptors
What if, instead of running a process-data program on this machine, we want to run it on another machine? No problem. We make a TCP connection to a process-data server on the remote machine. On the local machine, we have generate-data writing to the TCP connection, and consume-data reading from the TCP connection…
3494
3495
Do Files want to be Actors?
Is 1970s distributed systems theory finally meeting 2020s kernel development?
3496
The messy reality of SIMD (vector) functions
We’ve discussed SIMD and vectorization extensively on this blog, and it was only a matter of time before SIMD (or vector) functions came up. In this post, we explore what SIMD functions are, when they are useful, and how to declare and use them effectively. A SIMD function is a function that processes more than… Read
3497
Using uninitialized memory for fun and profit (2008)
This is the story of a clever trick that's been around for at least 35 years, in which array values can be left uninitialized and then read during normal operations, yet the code behaves correctly no matter what garbage is sitting in the array. Like the best programming tricks, this one is the right tool for the job…
3498
Hyprland Crash Course
For the past week I have been configuring hyprland and using it as my daily driver. Coming from major Desktop Environments like KDE or Gnome, this was definitely quite challanging, specially when implementing features that we take it for granted on these DEs, like screen sharing or screenshot annotating.
3499
The Performance Cost of CORS Requests on Single-Page Applications
The title may lead you to think that this post is another ranting post about the downside of a “Single Page Application”. It is more about…
3500
Considering performance in the small is not “premature optimization”
DISCLAIMER : The following are my own personal opinions and are not shared, sanctioned or endorsed by anybody in particular, especially my employer. Any criticisms expressed herein are of a general nature and are neither inspired by nor directed at any person, entity, or product in particular. Links to other online…
3501
3502
My Experience with Nix on OS X
Some time ago, I’ve moved this jekyll-based blog from GitHub Pages to a self-hosted NixOS server. A few weeks ago, I’ve also moved some parts of my local OS X environment from homebrew over to nix.
3503
All Software is Legacy
In what may be judged in years to come as a moment of madness, I have volunteered to be the primary maintainer of the Perl CGI module (CGI.pm). For the non-technical readers of this post: CGI.pm is a few thousand lines of code that in the mid to late nineties, and even some years later, was helping many websites…
3504
Zero-Copy GPU Inference from WebAssembly on Apple Silicon
A WebAssembly module's linear memory can be shared directly with the Apple Silicon GPU: no copies, no serialization, no intermediate buffers. Here's how the zero-copy chain works, what we measured, and what it enables for stateful AI inference.
3505
Splitting the Ping
Ping is one of the fundamental pillars of networking. It’s simple, universally supported, and is normally one of the few things that is shipped with all network stacks.
3506
3507
jwz: Apple recently broke Ctrl-Y
Ever since MacOS 10.0 was released, text fields have supported Emacs bindings for the single-character Control commands, showing that there were people inside Apple (and, presumably, NeXT) who were right-thinking and sensible. But some time late in the 10.6 release cycle, and continuing into 10.7.1, the binding for…
3508
Java Virtual Threads Ate My Memory: A Web Crawler's Tale of Speed vs. Memory
I built a simple web crawler using good old platform threads. It was just a multithreaded crawler, nothing fancy. But then, curiosity…
3509
Zero or Sign Extend
A while back I had to deal with a bit-packed format that contained a list of integer values encoded in one of a pre-defined sets of bit widths, where both the allowed bit widths and the signed-ness…
3510
RISC-V SBI and the full boot process
Detailed explanation on how RISC-V boot process works and what role SBI has in the RISC-V software stack. Concrete example with OpenSBI.