Huawei is one of China’s largest technology companies, with enterprise products spanning everything from servers to networking equipment. All of those products require advanced chips to remain relevant. Huawei has invested in developing its own chips with…

“All innovation comes from industry is just wrong, universities invented many useful things.” But that’s not the argument. Nobody thinks that Knuth contributed nothing to software programming. Rather the point is that the direction of the arrow is almost…

« Normal science, the activity in which most scientists inevitably spend most all their time, is predicated on the assumption that the scientific community knows what the world is like. Normal science often suppresses fundamental novelties because they are…

One of my most popular blog posts of all times is  Data alignment for speed: myth or reality? According to my dashboard, hundreds of people a week still load the old blog post. A few times a year, I get an email from someone who disagrees. The blog post makes…

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Today, we’re used to desktop processors with 16 or more cores, and several times that in server CPUs. But even prior to 2010, Intel and AMD were working hard to reach higher core counts. AMD’s “Magny Cours”, or Opteron 6000 series, was one such effort. Looking…

The Apple M2, introduced in 2022, and the Apple M4, launched in 2024, are both ARM-based system-on-chip (SoC) designs featuring unified memory architecture. That is, they use the same memory for both graphics (GPU) and main computations (CPU). The M2 processor…

AMD Zen 1 的 BTB 结构分析¶ 背景¶ AMD Zen 1 是 AMD 的 Zen 系列的第一代微架构。在之前，我们分析了 ARM Neoverse N1 和 V1 的 BTB，那么现在也把视线转到 AMD 上，看看 AMD 的 Zen 系列的 BTB 是如何演进的。 官方信息¶ AMD 在 Software Optimization Guide for AMD Family 17h Processors 中有如下的表述： The branch target buffer (BTB) is a…

Lion Cove is Intel’s latest high performance CPU architecture. Compared to its predecessor, Raptor Cove, Intel’s newest core can sustain more instructions per cycle, reorganizes the execution engine, and adds an extra level to the data cache hierarchy. The…

JSON, or JavaScript Object Notation, is a lightweight data-interchange format. It is widely used for transmitting data between a server and a web application, due to its simplicity and compatibility with many programming languages. The JSON format has a simple…

C and C++ compilers like GCC first take your code and produce assembly, typically a pure ASCII output (so just basic English characters). This assembly code is a low-level representation of the program, using mnemonic instructions specific to the target processor…

背景 最近两个月去了法国和日本开会，发现 eSIM 在旅游时使用非常方便，我们可以直接在网上购买旅行 SIM 卡套餐然后扫码下载，主要好处包括： 套餐自由选择，可以按照自己最低需求购买低价套餐，不必担心部分 SIM 卡无法流量充值的问题 低可用性风险，遇到问题随时可以下载新的 SIM 卡使用，不必等待快递 灵活切换运营商，遇到某个运营商信号不好，此时有其他运营商 eSIM 时，可以在手机上点击菜单直接完成切换，而无需带着取卡针更换实体 SIM 卡 （比如我们去 Waseda 开会发现 docomo 和 SoftBank…