# Kobzol/hardware-effects

Demonstration of various hardware effects.

Repository: https://github.com/Kobzol/hardware-effects
Canonical: https://ross.abutalabs.com/products/hardware-effects
Language: C++
License: MIT
License Family: permissive
Last push: 2024-02-29T22:23:18+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 2853, "days_push": 916, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2999, forks 165 (observed 2026-08-28T04:07:37.360381+00:00)

## What it is
A collection of small C++ proof-of-concept programs demonstrating hardware effects like cache conflicts, branch misprediction, false sharing, and memory bandwidth saturation that degrade performance in surprising ways. Each example includes a README explaining the underlying CPU and OS architecture behavior.

## Use cases
- learn why my C++ program is slow despite good algorithms
- demonstrate cache effects to students
- understand branch misprediction penalties
- see false sharing in multithreaded code
- study memory hierarchy and prefetching behavior
- prepare for systems performance interviews

## When to choose
- teaching or learning low-level CPU performance concepts
- building intuition for hardware-aware optimization on x86-64
- looking for minimal reproducible examples of performance pitfalls

## When to avoid
- you need a production profiling or benchmarking tool
- you target non-x86 architectures like ARM
- you need NUMA or server-scale effects
- you want guaranteed reproducible results on your specific CPU

## Facets
- artifact type: learning-resource
- maturity: stable
- function: benchmarking, developer-tools
- domain: performance, hardware, education, tutorials
- platform: cpp
- tags: cpu-architecture, cache-effects, branch-prediction, memory-hierarchy, performance-education, demos, linux, x86-64

## Member repositories
- Kobzol/hardware-effects (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:37.360381+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T07:30:35.479266+00:00, confidence not recorded.
  - readme: https://github.com/Kobzol/hardware-effects (fetched 2026-08-28T04:07:37.360381+00:00, sha 3192822c548e)
- Data as of 2026-08-30T08:39:29.467469+00:00.