Hacker News: matja

New comment by matja in "Converting an Integer to a Decimal String in Under Two Nanoseconds"

matja — Sun, 24 May 2026 12:21:22 +0000

The problem is AVX-512 was disabled in later Intel Alder Lake CPUs, and later generation Intel desktop CPUs, so very few Intel desktop CPUs have AVX-512 now. Ironic that AMD has better support/performance for an ISA extension that Intel invented.

New comment by matja in "I spent 50 hours drawing a line graph"

matja — Sun, 24 May 2026 12:07:54 +0000

I loved hearing this comment in my mind :)

New comment by matja in "Regex Chess: A 2-ply minimax chess engine in 84,688 regular expressions"

matja — Tue, 19 May 2026 11:38:22 +0000

I was also thinking along the same lines. Interesting, but I'm not sure in which aspect it is an achievement, considering the loop isn't a regex.

Meanwhile, 1K ZX Chess takes fewer bytes of memory than the first four paragraphs from the post.

New comment by matja in "Removing fsync from our local storage engine"

matja — Sat, 09 May 2026 15:15:04 +0000

Even with O_DIRECT and aligned blocks, I still don't understand how the storage engine can return a "successful commit" to the client without a sync at some point, because a sync (IIRC) is the only way to guarantee an ATA/NVMe FUA command is sent, and the device write cache/buffer is committed.

New comment by matja in "Different language models learn similar number representations"

matja — Fri, 24 Apr 2026 15:36:16 +0000

The eigenvalue distribution looks somewhat similar to Benford's Law - isn't that expected for a human-curated corpus?

New comment by matja in "XOR'ing a register with itself is the idiom for zeroing it out. Why not sub?"

matja — Wed, 22 Apr 2026 15:32:54 +0000

SUB has higher latency than XOR on some Intel CPUs:

latency (L) and throughput (T) measurements from the InstLatx64 project (https://github.com/InstLatx64/InstLatx64) :

  | GenuineIntel | ArrowLake_08_LC | SUB r64, r64 | L: 0.26ns=  1.00c  | T:   0.03ns=   0.135c |
  | GenuineIntel | ArrowLake_08_LC | XOR r64, r64 | L: 0.03ns=  0.13c  | T:   0.03ns=   0.133c |
  | GenuineIntel | GoldmontPlus    | SUB r64, r64 | L: 0.67ns=  1.0 c  | T:   0.22ns=   0.33 c |
  | GenuineIntel | GoldmontPlus    | XOR r64, r64 | L: 0.22ns=  0.3 c  | T:   0.22ns=   0.33 c |
  | GenuineIntel | Denverton       | SUB r64, r64 | L: 0.50ns=  1.0 c  | T:   0.17ns=   0.33 c |
  | GenuineIntel | Denverton       | XOR r64, r64 | L: 0.17ns=  0.3 c  | T:   0.17ns=   0.33 c |

I couldn't find any AMD chips where the same is true.

New comment by matja in "XOR'ing a register with itself is the idiom for zeroing it out. Why not sub?"

matja — Wed, 22 Apr 2026 15:22:19 +0000

Alpha: r31, f31

New comment by matja in "The local LLM ecosystem doesn’t need Ollama"

matja — Thu, 16 Apr 2026 08:39:28 +0000

> This is a bit like saying stop using Ubuntu, use Debian instead.

Not really, because Ubuntu has always acknowledged Debian and explicitly documented the dependency:

> Debian is the rock on which Ubuntu is built.

> Ubuntu builds on the Debian architecture and infrastructure and collaborates widely with Debian developers, but there are important differences. Ubuntu has a distinctive user interface, a separate developer community (though many developers participate in both projects) and a different release process.

Source: https://ubuntu.com/community/docs/governance/debian

Ollama never has for llama.cpp. That's all that's being asked for, a credit.

New comment by matja in "Do you even need a database?"

matja — Wed, 15 Apr 2026 14:35:50 +0000

If you think files are easier than a database, check out https://danluu.com/file-consistency/

New comment by matja in "My adventure in designing API keys"

matja — Wed, 15 Apr 2026 10:10:48 +0000

What if the "slug" was a prefix for the API key revocation URL, so the API key was actually a valid URL that revoked itself if fetched/clicked? :)

New comment by matja in "My adventure in designing API keys"

matja — Wed, 15 Apr 2026 10:07:11 +0000

I suppose there could be two checksums, or two hashes: the public spec that can be used by API key scanners on the client side to detect leaks, and an internal hash with a secret nonce that is used to validate that the API key is potentially valid before needing to look it up in the database.

That lets clients detect leaks, but malicious clients cant generate lots of valid-looking keys to spam your API endpoint and generate database load for just looking up API keys.

New comment by matja in "Steam on Linux Use Skyrocketed Above 5% in March"

matja — Thu, 02 Apr 2026 17:09:44 +0000

Does Nvidia need to support Wayland, or does Wayland need to support Nvidia? I.e., what is the support at the API boundary which is missing?

New comment by matja in "Google releases Gemma 4 open models"

matja — Thu, 02 Apr 2026 17:07:58 +0000

I'm running Gemma 4 with the llama.cpp web UI.

https://unsloth.ai/docs/models/gemma-4 > Gemma 4 GGUFs > "Use this model" > llama.cpp > llama-server -hf unsloth/gemma-4-31B-it-GGUF:Q8_0

If you already have llama.cpp you might need to update it to support Gemma 4.

New comment by matja in "Steam on Linux Use Skyrocketed Above 5% in March"

matja — Thu, 02 Apr 2026 09:13:19 +0000

That's a good point that I hadn't considered. I've never had a laptop with Nvidia, I probably subconsciously avoided those dual GPU setups as they sounded hacky and I never really needed fast 3D on a laptop.

New comment by matja in "Steam on Linux Use Skyrocketed Above 5% in March"

matja — Thu, 02 Apr 2026 08:44:12 +0000

The "Nvidia on Linux compatibility" issues are something I wonder if I have side-stepped somehow either by lucky choice of GPUs, or lucky choice of Linux distros.

Was/is this a distro thing, or an actual issue?

Every Nvidia I've used [1] has worked perfectly, from the change for Xfree86 to Xorg, through the Compiz desktop wobbly window craze, to the introduction of GPGPU APIs like CUDA/OpenCL and recently Vulkan.

I do recall once helping a friend setup a Debian and a Ubuntu machine with Nvidia (which I never used before) and it took some figuring-out of how to install non-free drivers, so maybe my choices of Gentoo and Arch (not being as conservative towards non-free licenses as Debian/Ubuntu) always made it a non-issue?

[1] 6800 Ultra, 7800 GTX , 7900 GTX, 8800 GTX, GTX 280, GTX 480, GTX 680, GTX 760 Ti, RTX 2080, RTX 4080... probably missed some.

New comment by matja in "Artemis II is not safe to fly"

matja — Tue, 31 Mar 2026 11:01:50 +0000

I'm nowhere near qualified to say if the design is not safe, but I'm suprised the article doesn't mention that some heat shields are designed to indeed, blow chunks: https://en.wikipedia.org/wiki/Atmospheric_entry#Ablative

New comment by matja in "Apple discontinues the Mac Pro"

matja — Fri, 27 Mar 2026 11:16:21 +0000

Yeah 80GB/s total I/O bandwidth is a lot for a Mac, but desktop PCs have been doing 1TB/s (128x PCIe5) for years (Threadripper etc).

New comment by matja in "curl > /dev/sda: How I made a Linux distro that runs wget | dd"

matja — Tue, 24 Mar 2026 15:58:39 +0000

That sounds like the best way if keeping the filesystem is an option. In my case I wanted to also change filesystems and apply FDE, which is possible to do if the original filesystem supports online shrinking but many do not.

New comment by matja in "curl > /dev/sda: How I made a Linux distro that runs wget | dd"

matja — Tue, 24 Mar 2026 12:20:04 +0000

I totally missed part 2/3, thanks for linking!

New comment by matja in "curl > /dev/sda: How I made a Linux distro that runs wget | dd"

matja — Tue, 24 Mar 2026 12:08:31 +0000

> How do you unmount your OS’s disk while keeping the OS running to be able to overwrite itself?

I went down a similar rabbit-hole myself, with the goal of safely replacing the Linux installation on a disk that a machine is already running from (e.g. replace a VPS's setup image with one of your own) without needing a KVM-style remote access tool to the console.

The problem there is if you directly modify the disk when a filesystem is mounted on that disk then all bets are off in terms of corruption of the filesystem that's already on there and also the filesystem(s) you're writing over the top.

My solution was to kexec into a new kernel+initramfs which has a DHCP client and cURL in it - that effectively stops any filesystem access while the image is being written over the disk, then to just reboot.