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The most popular blog posts about systems & performance on Hacker News. 4,389 posts.
While considering concurrent queue design I came up with a generic, lock-free queue that fits in a 32-bit integer. The queue is “generic” in that a single implementation supports elements of any arbitrary type, despite an implementation in C. It’s lock-free in that there is guaranteed system-wide progress. It can…
Although the title of this article might suggest otherwise, I don’t dislike Unreal’s multiplayer features. As someone who has worked on two different multiplayer games in Unreal, I enjo…
T The problem Every once in a while I get involuntarily dragged into heat...
My home network (which is also my work network) is a standard-issue Comcast cable hookup. In spite of a tolerable 120 megabits down, my experience of daily Internet use is regularly frustrating. Video streams and video chats drop in quality...
Rene Schallner (@renerocksai): software engineer turned AI researcher and engineer, in Vienna.
…"‘Our speech interposes itself between apprehension and truth like a dusty pane or warped mirror. The tongue of Eden was like a flawless glass; a light of total understanding streamed through it. Thus Babel was a second Fall.’ And Isaac the Blind, an early Kabbalist, said that, to quote Gershom Scholem’s translation…
In the previous episode of “Simple Changes to Shrink Chrome” I discussed how deleting ‘const’ from a few key locations could lead to dramatic size savings, due to a VC++ com…
CPUs like to operate on data types such as uint8_t , uint16_t , uint32_t , and uint64_t . These data types can be viewed as integers modulo 2 8 , 2 16 , 2 32 , and 2 64 respectively. Addition and multiplication can be defined on these integers modulo 2 N in a way which is familiar to most people; for example, in…
This form of Spectre can be used to attack a broad range of software -- operating systems, device drivers, web APIs, database systems, and almost anything else that receives untrusted input and may run on the same computer as untrusted code. Because large programs can contain literally millions of conditional branches…
If I give a programmer a string such as "9223372036854775808" and I ask them to convert it to an integer, they might do the following in C++: std::string s = .... uint64_t val; auto [ptr, ec] = std::from_chars(s.data(), s.data() + s.size(), val); if (ec != std::errc()) {} // I have an error ! // val … Continue reading…
For the last month or so, I’ve been playing with a new project during my work at Collabora, and as I’ve already briefly talked about at XDC 2018, it’s about time to talk about it to a wider audience.
Disclaimer: I used to work for Materialize which is one of the systems being compared in this post.
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…
We use distributed systems every day in the form of internet services. These systems are very useful, but also challenging to implement because networks are unpredictable. Whenever you send a message over the network, it is likely to arrive quite quickly, but it’s possible that it might be delayed for a long time, or…
The Unix command line is full of surprises. For instance: did you know that the OS X version of the ls tool, most frequently used to get a list of the files in the current working directory, recognizes no fewer than 38 different flags?
The Personal blog and musings of Chris Penner, a designer, developer and future opsimath.
About the fatal perils and traps of many modern tools that handle "shell commands" as passed through `system(3)` or `sh -c`. Or, how by the end of 2020, we still haven't given up on shell's equivalent "SQL building", or how shell's equivalent "SQL injection" still thrives in our engineering world... Plus a `glibc`…
I was a huge Archimedes fan and still have an A310, an A5000, a RiscPC and a RasPi running RISC OS. But no, I have to disagree. RISC OS was a hastily-done rescue effort after Acorn PARC failed to make ARX work well enough. I helped to arrange this talk by the project lead a few years ago. RISC OS…
This article has now been extensively corrected and modified.
You're probably reading this page because you've attempted to access some part of my blog (Wandering Thoughts) or CSpace , the wiki thing it's part of. Unfortunately you're using a browser version that my anti-crawler precautions consider suspicious, most often because it's too old (most often this applies to versions…
Ginseng: keeping secrets in registers when you distrust the operating system Yun & Zhong et al., NDSS’19 Suppose you did go to the extreme length of establishing an unconditional root of …
Any time Facebook talks about technical matters I tend to listen. They have a track record of demonstrating engineering leadership in several spaces. And, unlike many companies that just talk, Facebook often gives others access to those ideas via source code and healthy open source projects. It's rare to see a company…
Ever since the first EC2 instances launched — the ones which were retrospectively named "m1.small" — Amazon has relied on the Xen hypervisor. No longer: C5 instances use KVM. This sounds like it would be a problem, but in fact that change didn't bother FreeBSD at all: Now that everything uses hardware-based paging…
Let me tell you about the still-not-defunct real-time log processing pipeline we built at my now-defunct last job. It handled logs from a la...
I’m setting up an old Dell box (2011-era tech). I was migrating to some new boot drives and setting up grub on them again. Got to the point of deleting the old boot entries and adding new ones, and got an error like Could not prepare boot variable: No space left on device. Weird, because there weren’t that many EFI…
Since Version 10.10 (Yosemite), OS X contains Hypervisor.framework, which provides a thin user mode abstraction of the Intel VT features. It enables apps to use virtualization without the need of a kernel extension (KEXT) – which makes them compatible with the OS X App Store guidelines.
