ccdpin

ccdpin is a lightweight wrapper for launching games with explicit CPU affinity control. It's designed for Steam launch options.

Usage

ccdpin [flags] [--] COMMAND [args...]

Steam Launch Options

Add to your game's launch options in Steam:

ccdpin %command%

With environment variables:

PROTON_ENABLE_HDR=1 ccdpin %command%

How It Works

1. Detect topology - Same as ccdbind, reads L3 cache groups
2. Pin OS slices - Temporarily pin slices to OS CPUs
3. Launch game - Start game pinned to GAME CPUs
4. Restore - When game exits, restore original settings

Launch Methods

ccdpin tries these in order:

1. systemd-run (preferred) - Creates a transient scope

   systemd-run --user --scope -p AllowedCPUs=8-15 game.exe

2. taskset (fallback) - Direct CPU affinity

   taskset -c 8-15 game.exe

CLI Flags

Examples

# Print detected topology
ccdpin --print

# Swap CPU groups (game on CPU0's CCD)
ccdpin --swap %command%

# Don't pin OS slices
ccdpin --no-os-pin %command%

# Custom slice list
ccdpin --os-slices "app.slice session.slice" %command%

# Test without running
ccdpin --dry-run echo test

Environment Variables

For compatibility with shell scripts, ccdpin supports environment variable configuration:

Examples

# Override CPU groups
STEAM_CCD_GAME_CPUS="8-15" ccdpin %command%

# Swap groups
STEAM_CCD_SWAP=1 ccdpin %command%

# Debug mode
STEAM_CCD_DEBUG=1 ccdpin %command%

Steam Launch Options Examples

Basic usage

ccdpin %command%

With Proton settings

PROTON_ENABLE_HDR=1 DXVK_ASYNC=1 ccdpin %command%

Swap CPU groups

Some games perform better on CPU0's CCD:

ccdpin --swap %command%

Game-specific CPU override

For a specific game that needs more cores:

STEAM_CCD_GAME_CPUS="4-23" ccdpin %command%

Debug issues

STEAM_CCD_DEBUG=1 ccdpin %command% 2>&1 | tee /tmp/ccdpin.log

Using with ccdbind

ccdpin and ccdbind can work together:

Recommended Setup

1. Run ccdbind as a service for automatic management
2. Use ccdpin %command% for launch-time guarantees
3. Use ccdpin --swap for games that need it

State Management

ccdpin maintains its own state for OS-slice pinning:

~/.local/state/ccdpin/
├── lock          # Prevents concurrent runs
└── refcount      # Tracks active games

When multiple games are launched with ccdpin:

• First launch pins OS slices
• Subsequent launches increment refcount
• Last game exit restores original settings

Troubleshooting

Game doesn't launch

# Test with a simple command
ccdpin --dry-run echo "test"

# Check if systemd-run is available
which systemd-run

# Try with taskset fallback
ccdpin --no-systemd %command%

Performance not improved

1. Verify topology detection:

   ccdpin --print

2. Check if game is actually pinned:

   taskset -p <game_pid>

3. Try swapping groups:

   ccdpin --swap %command%

OS becomes unresponsive

Reduce pinned slices:

STEAM_CCD_OS_SLICES="background.slice" ccdpin %command%

Or disable OS pinning entirely:

ccdpin --no-os-pin %command%

Conflicts with ccdbind

If both tools seem to conflict:

# Check ccdbind status
ccdbind status

# Temporarily stop daemon for testing
systemctl --user stop ccdbind.service
ccdpin %command%

Comparison: ccdpin vs ccdbind