zebp / procpin

A daemon for pinning processes to Zen CCXes

procpin

A daemon for pinning processes to specific Zen CCXes.

Running

systemd

Running under systemd is the same as any other service, simply start and enable the service.

systemctl enable procpin.service
systemctl start procpin.service

Configuration

To configure the procpin daemon create a procpin.toml file in /etc.

Sample configuration

[programs]
hx = 0 # Pin Helix to CCX 1
ffmpeg = [2, 3] # Pin ffmpeg to either CCX 3 or 4.

Why would I want to pin processes?

AMD's Zen series of architectures group cores into core complexes (commonly referred to as CCXes) with a shared L3 cache. When the scheduler moves processes to a different CCX there can be a performance penalty as there's higher latency to access L3 cache in the other complex, which can be critical for games. On top of that, starting with Zen 2, processors are built using multiple chips per socket called "chiplets". If a process moves between chiplets there is an even larger latency penalty and performance can be drastically impacted.