Hacker News: fsfod

New comment by fsfod in "Deconstructing the LuaJIT Pseudo Memory Leak"

fsfod — Tue, 13 Jan 2026 15:07:37 +0000

I think they just swapped out LuaJIT's modified built-it dlmalloc[1] with some standard allocator. Then just set some turning values of the allocator to make to more eager to return pages with no allocations left to the OS. LuaJIT has always had pluggable allocator system you can set at state construction time[2], it did have a restriction you could only use the built-it allocator for 64 bit builds if you don't use the GC64 build option, but thats been default enabled for a while now.

[1]: https://github.com/LuaJIT/LuaJIT/blob/v2.1/src/lj_alloc.c

[2]: https://github.com/LuaJIT/LuaJIT/blob/707c12bf00dafdfd3899b1...

New comment by fsfod in "Arborium: Tree-sitter code highlighting with Native and WASM targets"

fsfod — Mon, 15 Dec 2025 20:13:09 +0000

GitHub had to solve the same problem when speeding up there code viewer.

https://github.blog/engineering/architecture-optimization/cr...

New comment by fsfod in "Program-of-Thought Prompting Outperforms Chain-of-Thought by 15% (2022)"

fsfod — Sun, 30 Nov 2025 21:28:16 +0000

I remember seeing that GPT-5 had two python tools defined in its leaked prompt one them would hide the output from user visible chain of thought UI.

New comment by fsfod in "CDC File Transfer"

fsfod — Wed, 01 Oct 2025 07:02:05 +0000

Someone already created that[1] using custom kernel driver and there own CDN, but they seem to of abandoned it[2], maybe because they would of attracted Valve's wrath trying to monetized it.

[1] https://web.archive.org/web/20250517130138/https://venusoft....

[2] https://venusoft.net/#home

New comment by fsfod in "IRHash: Efficient Multi-Language Compiler Caching by IR-Level Hashing"

fsfod — Sun, 07 Sep 2025 18:58:46 +0000

There was commercial fork of clang zapcc[1] that did caching of headers and template instantiations with an in memory client server system[2], but idk if they solved all the correctness issues or not before abandoning it.

[1] https://github.com/yrnkrn/zapcc

[2] https://lists.llvm.org/pipermail/cfe-dev/2015-May/043155.htm...

New comment by fsfod in ".NET 10 Preview 6 brings JIT improvements, one-shot tool execution"

fsfod — Thu, 31 Jul 2025 00:13:27 +0000

Maybe they will use this chance to finally switch it away from the .NET Framework to the modern dotnet runtime with its many years optimizations.

New comment by fsfod in "Transition to using 16 KB page sizes for Android apps and games"

fsfod — Tue, 15 Jul 2025 17:31:20 +0000

AMD also switched to 16k(4 x 4K) down from 8 in Zen1 for there PTE Coalescing system that is effectively run length like compression of page table entries with sequential addresses in to one TLB slot.

New comment by fsfod in "Insurers launch cover for losses caused by AI chatbot errors"

fsfod — Wed, 14 May 2025 02:19:32 +0000

I wonder if the premiums scale up depending on the temperature used for the model output.

New comment by fsfod in "Wild – A fast linker for Linux"

fsfod — Fri, 24 Jan 2025 17:11:27 +0000

You can sort of do that with some of LLVM's JIT systems https://llvm.org/docs/JITLink.html, I'm surprised that no one has yet made a edit and continue system using it.

New comment by fsfod in "Hackers Exploited a PC Driving SIM to Pull Off Disney Data Breach"

fsfod — Tue, 30 Jul 2024 12:15:14 +0000

I personally just went down the route of stripping down the FFI system when integrating LuaIT. It included things like removing the ability to define new ffi types\functions or loading libraries, as well as removing most casting and pointer indexing.

New comment by fsfod in "Pallene: A statically compiled companion language for Lua"

fsfod — Mon, 29 Jul 2024 14:07:36 +0000

That binary search benchmark probably triggers a trace explosion in LuaJIT like I've found quicksort does. If your lucky the function gets trace blacklisted, if not it ends up hitting the default max number of traces and throwing away all the JIT'ed code and repeating the same thing over and over.

New comment by fsfod in "Show HN: Dut – a fast Linux disk usage calculator"

fsfod — Thu, 11 Jul 2024 15:46:08 +0000

There is a fork of Windirstat that also reads the NTFS MFT as well https://github.com/ariccio/altWinDirStat

New comment by fsfod in "DaScript: Fast and Versatile Scripting Language"

fsfod — Fri, 27 Oct 2023 19:20:20 +0000

It looks like there comparing apples to oranges for many of the benchmarks by using structs for daScript vs tables for Lua.

New comment by fsfod in "MMO Architecture: Source of truth, Dataflows, I/O bottlenecks and how to solve"

fsfod — Fri, 29 Sep 2023 16:09:56 +0000

Its a book https://whenitsready.com/wowdiary/ originally sold as a kickstarter by one of the original Blizzard mappers made from notes they wrote while working on original wow. They did some AMAs[1][2] with other wow developers that sort of touch on some of the topics discussed here.

[1] https://www.reddit.com/r/wow/comments/9huows/ama_former_wow_...

[2] https://www.reddit.com/r/classicwow/comments/9fb2bo/john_sta...

New comment by fsfod in "Dynamic bit shuffle using AVX-512"

fsfod — Fri, 30 Jun 2023 12:51:04 +0000

At least AMD kept AVX-512 in there small Zen4C cores and just sacrificed some cache instead. I have to wonder if it was intel marketing that killed off working AVX-512 in consumer P-cores after they were released because the E-cores just become dead weight with AVX-512 enabled.

New comment by fsfod in "Microsoft broke a Chrome feature to promote Edge"

fsfod — Tue, 02 May 2023 17:57:33 +0000

I thought the whole point of the hash was it could change arbitrarily with windows updates to stop programs reverse engineering it and then setting file associations or browser choice directly in the registry.

Although not sure if it has ever changed before though just by quickly scanning the change log for this app people were using to set it https://kolbi.cz/blog/2017/10/25/setuserfta-userchoice-hash-...

New comment by fsfod in "Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%"

fsfod — Mon, 10 Apr 2023 19:39:19 +0000

I would think anything with a JIT that is toggling the page protection for machine code many times a second, based on a very quick reading of the bug report talking about VirtualProtect calls and the processing of ETW events for them by defender.

New comment by fsfod in "AVX 512 will be the future"

fsfod — Mon, 28 Nov 2022 21:59:29 +0000

MSVC recently added there own version[1] of it controlled with a [[msvc::dispatch]] attribute thats needs an experimental compiler flag I think still.

1: C++ Function Multiversioning in Windows https://www.youtube.com/watch?v=LTM1was1dTU

New comment by fsfod in "Building the fastest Lua interpreter automatically"

fsfod — Wed, 23 Nov 2022 00:59:02 +0000

The author also worked on the Copy-and-Patch Compilation paper[1], I wonder if they are going to use the same idea for ones of tiers of the JIT idk if it would beat LuaJIT's JIT for code compilation speed but the machine code could be faster.

[1] https://arxiv.org/abs/2011.13127

New comment by fsfod in "Pointer Tagging for x86 Systems"

fsfod — Thu, 31 Mar 2022 21:02:48 +0000

I know at least the Java ZGC use top bits as metadata for a load barrier to check for relocated objects. They fake hardware pointer masking by mapping the the same heap to multiple addresses https://www.opsian.com/blog/javas-new-zgc-is-very-exciting/