# facebookincubator/below

A time traveling resource monitor for modern Linux systems

Repository: https://github.com/facebookincubator/below
Canonical: https://ross.abutalabs.com/products/below
Language: Rust
License: Apache-2.0
License Family: permissive
Last push: 2026-08-26T18:18:38+00:00

## Health v2 (maintenance only)
Score: 73/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 25, longevity 100
- inputs: {"age_days": 2387, "days_push": 7, "days_rel": 343, "gap_med": 104.5, "n_releases_24m": 3}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2493, forks 113 (observed 2026-08-28T04:06:56.473567+00:00)

## What it is
below is an interactive Rust-based system resource monitor for Linux that records historical system data and lets you view, replay, and dump it. It supports cgroup hierarchies, process stats, pressure stall information (PSI), and script-friendly output formats like JSON, CSV, and OpenMetrics.

## Use cases
- monitor cpu memory and disk usage on linux
- replay historical system resource data after an incident
- view cgroup hierarchy and process stats
- record system metrics continuously with a daemon
- export system stats as json or csv for scripts
- check pressure stall information psi
- debug what caused a past performance spike

## When to choose
- you need historical 'time traveling' system data, not just a live snapshot
- you run modern Linux with cgroup2 and want cgroup-aware monitoring
- you want scriptable dumps in JSON, CSV, or OpenMetrics
- you prefer a lightweight single-binary Rust tool over atop or htop

## When to avoid
- you still rely on cgroup v1, which below does not support
- you need a cross-platform monitor for macOS or Windows
- you need alerting or dashboards rather than interactive inspection
- you need network-level or application-level monitoring rather than system resources

## Facets
- artifact type: cli-tool
- maturity: active
- function: monitoring, cli, terminal-ui, logging, analytics
- domain: monitoring, operating-systems, performance
- platform: cli, rust
- tags: system-monitor, cgroups, psi, resource-monitoring, time-series, replay, atop-alternative, devops, command-line, linux, docker

## Member repositories
- facebookincubator/below (main) score 73

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:06:56.473567+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 2026-08-30T02:27:18.609495+00:00, confidence not recorded.
  - readme: https://github.com/facebookincubator/below (fetched 2026-08-28T04:06:56.473567+00:00, sha 854c4ae03b2c)
  - registry_crates: https://crates.io/api/v1/crates/below (fetched 2026-08-29T10:09:27.041485+00:00, sha e38a400c08cc)
- Data as of 2026-08-30T08:39:29.467469+00:00.