Daniel Lemire's blog
19 random digits is not enough to uniquely identify all human beings

Suppose that you assigned everyone an 19 digit number. What is the probability that two human beings would have the same number? It is an instance of the Birthday’s paradox.

Assuming that there are 8 billion people, the probability that at least two of them end up with the same number is given by the following table:

If you want the probability to be effectively zero, you should use 30 digits or so.

source

Daniel Lemire's blog
Consider using constexpr static function variables for performance in C++

Telegraph | source

Telegraph

Consider using constexpr static function variables for perfo…

When programming, we often need constant variables that are used within a single function. For example, you may want to look up characters from a table. The following function is efficient: char table(int idx) { const char array[] = {'z', 'b', 'k', 'd'};…

Daniel Lemire's blog
Science and Technology links (March 11 2023)

Telegraph | source

Telegraph

Science and Technology links (March 11 2023)

Robert Metcalfe won the Turing Award (the ‘Computer Science Nobel Prize’) for his work on early networking. According to DBLP, Metcalfe published 11 journal articles and 7 peer-review conference papers. Metcalfe was denied his PhD at first. Among other things…

Chips and Cheese
Loongson’s 3A5000: China’s Best Shot?
#ChipAndCheese

Telegraph | source
(author: clamchowder)

Telegraph

Loongson’s 3A5000: China’s Best Shot?

We at Chips and Cheese have covered two Chinese CPU architectures: Zhaoxin’s x86 compatible Lujiazui architecture found in the KX-6000 series of CPUs and Phytium’s ARM compatible FT663 architecture found in the D2000 series of CPUs. Zhaoxin was founded in…

#今日生草
启动页表直接放进data段

#龙芯 #JamesAslan
https://zhuanlan.zhihu.com/p/620310569

知乎专栏

ARM Cortex X1微架构（下）：向山进发

幕间在上篇中我们主要探究了Arm Cortex X1微架构的取指前端和后端执行单元配置，下篇我们继续探究Mid Core、访存子系统、核外系统。X1 为数不多的可以称得上是变动的修改都发生在访存子系统部分。 JamesAslan：ARM…

Daniel Lemire's blog
Programming-language popularity by GitHub pull requests

Telegraph | source

Telegraph

Programming-language popularity by GitHub pull requests

GitHub is probably the most popular software repository in the world. One important feature on GitHub is the ‘pull request’: we often contribute to a piece of software by proposing changes to a piece of code. The number of pull requests is not, per se, an…

一个存在的世界

https://jia.je/hardware/2023/04/07/ram-read-write-collision/

去年龙芯杯被xilinx的双端口bram 1w1r的时候是无效读坑了，ftb的bug修了好几天

Daniel Lemire's blog
Are your memory-bound benchmarking timings normally distributed?

Telegraph | source

Telegraph

Are your memory-bound benchmarking timings normally distribu…

When optimizing software, we routinely measure the time that takes a given function or task. The typical assumption is that we get a normal distribution, and so we should therefore report the average time. I believe that this hidden assumption (normality)…

今日震惊
：时序不满足怎么办？
：加电压。

Daniel Lemire's blog
What are we going to do about ChatGPT?

Telegraph | source

Telegraph

What are we going to do about ChatGPT?

Generative artificial intelligence, and in particular ChatGPT, has taken the world by storm. Some intellectuals are proposing we create a worldwide ban on advanced AI research, using military operations if needed. Many leading researchers and pundits are…

#龙芯 #JamesAslan
https://zhuanlan.zhihu.com/p/619033328

知乎专栏

ARM Cortex X1微架构评测（上）：向山进发

前言作为IP vendor，ARM公司的产品受众广泛；除了为人所熟知的终端厂商之外，还有各式嵌入式用途。因此在设计核心时ARM需要兼顾各种使用场景，做到表现尽可能均衡的同时还需严控成本，ARM对微架构efficiency的执著…

Easton Man's Channel

#今日看了什么 https://zhuanlan.zhihu.com/p/348266543

是，是丧心病狂

#今日看了什么
https://zhuanlan.zhihu.com/p/348266543

知乎专栏

Tremont：双份解码，双倍快乐？

拖延症拖到Gracemont都发布了，不能再拖了！ 阅读本文前，建议先看上一篇文章： XZiar：分支预测，uOP，乱序执行 Tremont是Intel在19年下半年公布的新一代atom微架构，上一代则是Goldmont/Goldmont Plus。 实际产…

#今日看了什么
https://zhuanlan.zhihu.com/p/618704031

Chips and Cheese
AMD’s HD 6950 vs RX 6900 XT: What Does Adding 50 Do?
#ChipAndCheese

Telegraph | source
(author: clamchowder)

Telegraph

AMD’s HD 6950 vs RX 6900 XT: What Does Adding 50 Do?

Note the publish day of this article. There will be a proper one on Terascale 3 later on, don’t worry. But for now, happy April Fools Day! Prestige is everything for computer hardware manufacturers. A few percentage points may not make or break someone’s…

#今日看了什么
https://github.com/corundum/corundum

GitHub

GitHub - corundum/corundum: Open source FPGA-based NIC and platform for in-network compute

Open source FPGA-based NIC and platform for in-network compute - corundum/corundum

乐，verilator 成功 fuzz 出了 clang 的锅