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The most popular blog posts about systems & performance on Hacker News. 391 posts.
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…
Yesterday Lauri Vasama showed me this awesome Godbolt: struct S { static std::unique_ptr<S> make() noexcept; ~S(); static std::unique_ptr<S> factory() { std::unique_ptr<S> s = S::make(); return M(s); } }; void take_ownership(S*) noexcept; void test() { std::unique_ptr<S> p = S::factory()…
A decision that arises over and over when designing concurrent programs is whether to represent program state in control flow or as data. This post is about what that decision means and how to approach it. Done well, taking program state stored in data and storing it instead in control flow can make programs much…
Graphing TLA+ state spaces for fun and profit.
A short tale of how horrible code yields clean performance.
The database zeitgeist has decided that ANSI SQL '92 isn't enough. We need something better.
This is the second post in the series about effortless performance improvements in C++. Check the first post to get the full story!
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…
Detailed explanation on how RISC-V boot process works and what role SBI has in the RISC-V software stack. Concrete example with OpenSBI.
This post describes the design and implementation of a runtime benchmark suite for measuring the performance of Rust programs, which was recently added into the Rust compiler suite. I have recently blogged about how the whole benchmark suite works, so feel free to read that post first if you want to gather a bit more…
What is a LAN? What is a network segment? How are L1, L2, and L3 segments related? What does it take to send an IP packet from one host to another? What is the difference between LAN, VLAN, and VXLAN?
I’ve been writing a pubsub listener for work recently and had this silly “shower thought”: the ideal queue should be empty. Why? If the queue is not empty, it means that whatever job is consuming from the queue is not keeping up with messages coming into it. Ok, then if queues are supposed to be empty, then what are…
Using assembly language test loops to understand the differences between M1 Pro and M3 Pro CPU cores casts new light on their differences.
bfs is a tool I wrote to do b readth- f irst s earch through a filesystem. It started out simply enough, but over the years it’s grown to include almost every feature from every other find implementation I could find, plus many of its own innovations. The new 3.0 release series includes the biggest new feature so far…
In this post, we will discuss the challenges of programming with locks and how the C++ language offers some useful tools to make it easier. We will start with an example in C and then use C++ to improve upon it in steps. The example APIs are based on real-life APIs from the SerenityOS kernel.
If it’s so easy to uninstall a troublesome RSR, why can’t we simply roll back to a previous version of macOS, like we did in High Sierra?
I recently started exploring link-time optimisation (LTO), which I used to think was just a single boolean choice in the compilation and linking workflow, and perhaps it was like that a while ago… I’ve learned that these days, there are many different dimensions of LTO across compilers and linkers today and more…
(New to this series? Consider starting from part 1) At the end of the last post, DbgRs could finally set breakpoints. That was the last really critical feature needed for controlling execution of a program. Now that it can stop on an arbitrary function or code location, the next step is to find more information about…
In my video about the Raspberry Pi 5, I mentioned the new external PCIe port makes it possible to boot the standard Pi 5 model B directly off NVMe storage—an option which is much faster and more reliable than standard microSD storage (even with industrial-rated cards!). Enabling NVMe boot is pretty easy, you add a…
There is this growing sentiment in tech that stacking more and more layers of complexity to reach the sacrosanct "infinite scalability" is not the way forward. First, because it rarely materializes: you need a lot of other things than fancy tech to reach millions of people. Second, because the tradeoffs
I used to run FreeBSD on older laptops – some more then a decade old – like my favorite ThinkPad W520 daily driver or ThinkPad X220 mobile companion. Today I will share with you my expe…
In the previous year I wrote a program, running on Intel's first microprocessor - 4004, that computes the first 255 digits of π. So let's continue our journey with the successor - the Intel 4040.
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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…
Windows XP I have a lot of fond memories of Windows XP and after feeling nostalgic, I was happy to find out that it’s relatively easy to take it for a spin on an ARM64 Mac using QEMU. I decided to install XP and an assortment of classic software one final time, taking screenshots of the whole process. This included…
SunOS is a historical UNIX operating system widely used from the mid 80s into the early/mid 90s. Older versions of QEMU struggled to emulate the SPARC platform that SunOS ran on, but QEMU v7.2 supports SPARC well enough to install and run SunOS without any unusual workarounds.
Someone mentioned cargo-bloat the other day and it reminded me that I have been wanting to measure the code size for generic functions in librsvg, and see if there are improvements to be made.
Intel's 386 processor (1985) was an important advance in the x86 architecture, not only moving to a 32-bit processor but also switching to a...
I always got fascinated by heap memory. Questions such as How heap memory is obtained from kernel? How efficiently memory is managed? Is it managed by kernel or by library or by application itself?…
