computer-architecture

Why should you care? If you've ever bought a laptop or smartphone, you've probably seen specifications like: 8 GB RAM 512 GB SSD 1 TB Storage Many beginners assume RAM and storage are the same thing because both are measured in gigabytes. They are not. Understanding the difference between RAM and storage helps you: Choose the right computer for your needs. Understand why applications become slow.…

Central Processing Unit (CPU) This is a general-purpose computer. It fetches an instruction, say “add 2”, from memory, applies that instruction to data, say “2”, then commits the result, “4”. Modern phone CPUs overlap these steps, allowing a single core to complete tens of billions of instructions per second. They contain six to eight cores, some high-performance and other smaller, power-efficien…

The Challenge of Combinatorial Complexity Large-scale combinatorial optimization problems—such as the classic Traveling Salesperson Problem (TSPLIB)—exhibit an exponential growth in the search space as the number of nodes increases. Traditional CPU-based approaches frequently run into parallelism limitations and bus latency bottlenecks when trying to explore multiple routes or states simultaneous…

Computer Science > Hardware Architecture Title:Characterizing Warp Divergence from Pascal to Blackwell View PDF HTML (experimental)Abstract:Since Volta introduced Independent Thread Scheduling (ITS), NVIDIA GPUs have been widely assumed to handle warp divergence in a fixed manner. We test this assumption across Ampere, Hopper, and datacenter and consumer Blackwell GPUs, using pre-ITS Pascal as a …

Global Navigation Satellite System (GNSS) spoofing--the transmission of counterfeit signals that trick receivers into reporting false positions or times--poses a growing threat to aviation, maritime shipping, power grids and autonomous systems. While machine learning has improved detection, most models fail when confronted with attack scenarios they have never seen before, because they learn data…

1. The Core Problem - Why Virtual Memory Exists Without virtual memory, every program would directly address physical RAM. This creates three fundamental problems: No isolation: process A could read or overwrite process B's memory. One buggy program could corrupt another or the OS itself. No abstraction: programs would need to know exactly where in physical RAM they're loaded. The same binary cou…

Every engineering student graduates with a transcript. The challenge is convincing an employer you're more than a GPA. In a job market where hiring managers are hunting for candidates who can solve problems on day one, practical experience has become more important than ever. Companies seek engineers who have tackled real problems, debugged real systems and built something that works outside the …

NUMA - Part 1: Cores, memory, and the distance between them Two virtual machines on the same host, configured identically, running the same workload. One of them is 20% slower than the other, consistently. Nothing is wrong with the workload, nothing is wrong with the host, no contention from other tenants. The slow one's memory just happens to be on the wrong side of an interconnect from the CPUs…

nvidia-peermem "Invalid argument" on Ubuntu — Fix GPUDirect RDMA with DMA-BUF TL;DR: If modprobe nvidia-peermem fails with Invalid argument ( -EINVAL ) on a system using the inbox Ubuntu InfiniBand stack ( rdma-core ), the module is not broken and you do not need it. nvidia-peermem requires an API that only exists in MLNX_OFED. On Hopper/Blackwell GPUs with the NVIDIA open driver, use DMA-BUF ins…

Occupancy Math on the AMD MI355X (CDNA4): A From-First-Principles Guide Ask a GPU kernel engineer how their kernel is doing and occupancy comes up within a sentence or two. It’s the number everyone quotes and the dial everyone reaches for — and, in my experience, the metric people understand least. Most treat it as an opaque percentage the profiler hands back. It isn’t. Occupancy is fully derivab…

The Return of Rigorous Full-System Timing Simulation Accurate timing simulation remains one of the most important tools in computer architecture, but modern systems have made cycle-level simulation increasingly impractical. Today’s platforms combine many-core CPUs, deep memory hierarchies, accelerators, complex I/O, and large software stacks, making detailed simulation extremely slow—often requir…

If you've ever deployed memory-bound workloads on AWS Graviton, you know that CPU compute speed is only part of the story. Another factor in real-world performance is how efficiently your code accesses the memory subsystem, specifically the cache hierarchy, interconnects, and physical DRAM. In this article, I will walk through how to use the Arm System Characterization Tool (ASCT) to analyze the …

Originally published on Alpinum Consulting The growth of open processor architectures has significantly increased the adoption of RISC‑V across embedded systems, AI accelerators, and high-performance computing platforms. This flexibility allows engineering teams to design processors with highly customised instruction sets and microarchitectures. However, this flexibility also increases verificati…

Kunal Pai, Harshil Patel, Erin Le, Noah Krim, Mahyar Samani, Bobby R. Bruce, Jason Lowe-Power

This is the fifth installment of the 80386 series. The FPGA CPU is now far enough along to run real software, and this post is about how it works. z386 is a 386-class CPU built around the original Intel microcode, in the same spirit as z8086. The core is not an instruction-by-instruction emulator in RTL. The goal is to recreate enough of the original machine that the recovered 386 control ROM can…