Dynamic swap space manager — auto-creates/removes 1GB swap chunks based on usage

Shell 100%

Find a file

Brad 8199433d63 Fix systemd unit: update env var names to match current code - BAUTOSWAP_CHUNK_SIZE → BAUTOSWAP_BASE_CHUNK (bytes) - BAUTOSWAP_LOW_FREE → BAUTOSWAP_ADD_THRESH - BAUTOSWAP_HIGH_FREE → BAUTOSWAP_REMOVE_BUFFER		2026-06-02 15:04:46 -07:00
bautoswap	Power-of-2 chunk scaling + dynamic removal threshold	2026-06-02 15:02:26 -07:00
bautoswap.service	Fix systemd unit: update env var names to match current code	2026-06-02 15:04:46 -07:00
install.sh	Add install script, power-of-2 adaptive polling	2026-06-02 14:55:47 -07:00
LICENSE	Initial commit: dynamic swap space manager	2026-06-02 14:52:26 -07:00
README.md	Power-of-2 chunk scaling + dynamic removal threshold	2026-06-02 15:02:26 -07:00

README.md

bautoswap

Dynamic swap space manager for Linux. Runs as a daemon, automatically creating and removing swap file chunks that scale in size.

How it works

Chunks scale as powers of 2: 1GB → 2GB → 4GB → 8GB → 16GB ...
Free swap < 512MB → adds next chunk
Free swap > last chunk size + 1GB → removes last chunk
No swap at all → creates first chunk immediately
Adaptive polling: 128s when idle, halves on action, doubles back when idle

Chunk scaling

chunk_00 = 1GB
chunk_01 = 2GB
chunk_02 = 4GB
chunk_03 = 8GB
chunk_04 = 16GB
...

With max 8 chunks: up to 255GB total swap (1+2+4+8+16+32+64+128).

Dynamic removal threshold

Removal threshold adapts to the last chunk's size:

1 chunk  (1GB):  remove when free > 1GB + 1GB = 2GB
2 chunks (3GB):  remove when free > 2GB + 1GB = 3GB
3 chunks (7GB):  remove when free > 4GB + 1GB = 5GB
4 chunks (15GB): remove when free > 8GB + 1GB = 9GB

Adaptive timing

Action taken → interval halves  (128→64→32→16→8→4→2→1s)
No action    → interval doubles (1→2→4→8→16→32→64→128s)

Install

One-liner

curl -fsSL https://raw.githubusercontent.com/bradcarnage/bautoswap/main/install.sh | sudo bash

Manual

sudo cp bautoswap /usr/local/bin/bautoswap
sudo chmod +x /usr/local/bin/bautoswap
sudo mkdir -p /var/swapfiles
sudo chmod 700 /var/swapfiles

Usage

Systemd (recommended)

# /etc/systemd/system/bautoswap.service
[Unit]
Description=Dynamic swap space manager
After=local-fs.target

[Service]
Type=simple
ExecStart=/usr/local/bin/bautoswap
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

sudo systemctl enable --now bautoswap

Manual

sudo bautoswap

Configuration

All settings via environment variables:

Variable	Default	Description
`BAUTOSWAP_BASE_CHUNK`	`1073741824` (1GB)	Starting chunk size in bytes (doubles each chunk)
`BAUTOSWAP_DIR`	`/var/swapfiles`	Directory for swap files
`BAUTOSWAP_ADD_THRESH`	`536870912` (512MB)	Add chunk when free swap below this (bytes)
`BAUTOSWAP_REMOVE_BUFFER`	`1073741824` (1GB)	Remove when free > last chunk size + this buffer
`BAUTOSWAP_MAX_CHUNKS`	`8`	Maximum number of chunks
`BAUTOSWAP_MAX_INTERVAL`	`128`	Max seconds between checks
`BAUTOSWAP_MIN_INTERVAL`	`1`	Min seconds between checks

Filesystem compatibility

Uses fallocate for fast allocation
Falls back to dd on CoW filesystems (btrfs, ZFS)

Log output

[2026-06-02 14:30:01] START: add_thresh=512M remove_buffer=1.0G base=1.0G max=8 interval=1-128s
[2026-06-02 14:30:01] STATUS: free=256M <512M, adding 1.0G chunk, interval=128s
[2026-06-02 14:30:01] ADD: /var/swapfiles/chunk_00 (1.0G), now 1 chunks, free=1.2G
[2026-06-02 14:30:02] STATUS: free=128M <512M, adding 2.0G chunk, interval=64s
[2026-06-02 14:30:02] ADD: /var/swapfiles/chunk_01 (2.0G), now 2 chunks, free=2.8G
[2026-06-02 14:35:01] STATUS: free=4.5G >3.0G, removing 2.0G chunk, interval=128s
[2026-06-02 14:35:01] REMOVE: /var/swapfiles/chunk_01 (2.0G), now 1 chunks, free=2.5G

License

MIT