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Daniel Lemire
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Faster JSON parsing with SVE2 on ARM processors
simd processors parsing
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19 September
Computer science professor who works on fast data processing; co-author of the simdjson parser and a weekly blogger about software performance since 2004.
18 September
Philosophy professor at UC Berkeley and creator of pandoc, the universal document converter, and of the CommonMark markdown specification.
Computer science professor who works on fast data processing; co-author of the simdjson parser and a weekly blogger about software performance since 2004.
Philosophy professor at UC Berkeley and creator of pandoc, the universal document converter, and of the CommonMark markdown specification.
15 September
Computer science professor who works on fast data processing; co-author of the simdjson parser and a weekly blogger about software performance since 2004.
A new fast_float release... fast_float is a super fast number parser in C++ (used by GCC, MySQL, your browser...). The latest release adds support for parsing numbers following the JavaScript standard, so things like 05.1 can be accepted (!!!). JavaScript Related
If anyone wants a nice side project... The fast number parsing fast_float (part of GCC, and other important systems like MySQL) is not always exact when dealing with 16-bit float parsing (specifically float16_t). That is, some number strings can lie in between two numbers and the rounding is wrong. In fact, nobody has done a proper analysis of the implementation to insure that it is correct. Yeah. I could ask my AI, but it is still work, especially because I do not trust anyone, not even an AI, to get it correct the first time around. Contributions invited. github.com
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Computer science professor who works on fast data processing; co-author of the simdjson parser and a weekly blogger about software performance since 2004.
Their words
Thus it appears that on the latest AMD and ARM processors subnormals might not be a concern. But they remain very much a performance issue under Intel processors.
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lemire.me
14 September
Programmer; makes Handmade Hero and teaches Performance-Aware Programming, and argues loudly about how software got slow.
11 September
Computer science professor who works on fast data processing; co-author of the simdjson parser and a weekly blogger about software performance since 2004.
What should be obvious is that inference, running a large language model, is the part that has to be cheap. Most of our hardware was not designed for that. LLM inference is limited by bandwidth. You do a great many matrix-vector multiplications against a huge weight matrix, and you barely reuse those weights. It is closer to streaming a video than to running a simulation or drawing a scene in a game. Graphics processors from Nvidia and others were built for something else. They pileed compute first, then bolted on high-bandwidth memory. It is expensive. An obvious answer is to invert the desi… LLMs Related
31 August
Programmer; makes Handmade Hero and teaches Performance-Aware Programming, and argues loudly about how software got slow.
22 August
Computer science professor who works on fast data processing; co-author of the simdjson parser and a weekly blogger about software performance since 2004.
19 August
Computer science professor who works on fast data processing; co-author of the simdjson parser and a weekly blogger about software performance since 2004.
Parsing IP addresses in C# at crazy speeds We are all familiar with IP addresses such as 192.168.0.1. They are typically written as four numbers in the range 0 to 255 inclusive, separated by dots. In C#, you can parse them with the standard library using IPAddre…
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17 August
Programmer; makes Handmade Hero and teaches Performance-Aware Programming, and argues loudly about how software got slow.
16 August
Programmer and teacher; writes on software, learning and the web, and makes the Coding Blocks video course.
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Dark nights, lots of coffee… This was fun!
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rakhim.org
3 August
Programmer; makes Handmade Hero and teaches Performance-Aware Programming, and argues loudly about how software got slow.
23 July
Software engineer; co-founder and former CTO of Tailscale, previously on the Go team at Google.
The thing to know about low-level programming is: as you go lower, things actually get *easier*. The difficulty is a mirage. Instead it is maddeningly obscure. You can spend an hour studying to read 6 lines of SIMD and learn all it says is "a + b + c". mitchellh.com
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22 July
Co-founder of Superlogical, started in 2026 to build server-side terminal infrastructure; creator of Ghostty. Co-founded HashiCorp and created Vagrant and Terraform before that.
4 June
Programmer on the Dart language at Google and author of Game Programming Patterns and Crafting Interpreters; previously a game developer at EA.
27 February
Software engineer and a long-time technical lead of the Go programming language; author of plan9port and of the research.swtch.com essays.
3 February
Non-fiction writer, podcaster and occasional TV host. Author of thirteen books including The Ghost Map, Where Good Ideas Come From and Extra Life, host of the PBS series How We Got To Now, and author of the Adjacent Possible newsletter on innovation.
19 January
Software engineer and a long-time technical lead of the Go programming language; author of plan9port and of the research.swtch.com essays.
Their words
Given the simplicity and speed of the algorithms in this post and the increasingly small deltas between successive algorithms, perhaps we are nearing an optimal solution.
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research.swtch.com
12 March 2025
Writer and consultant on formal methods and software correctness; author of Practical TLA+ and Logic for Programmers.
8 February 2017
Working on @ampcode. Writing registerspill.thorstenball.com. Once authored interpreterbook.com and compilerbook.com.
8 July 2013
Danish Mac developer; author of the TextMate text editor and founder of MacroMates.
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