Hybrid GPU Performance

Hybrid GPU Performance Guide

Hardware Setup

• iGPU: Intel Raptor Lake-S UHD Graphics
• dGPU: NVIDIA RTX 4060 Max-Q Mobile
• Physical Connection:
  • Laptop Display (eDP-1) → Intel iGPU
  • External Monitor (HDMI-A-5) → NVIDIA dGPU (physical HDMI port)

The Performance Problem

When your external monitor is connected directly to the NVIDIA HDMI port, it creates a Reverse PRIME situation:

┌──────────────────────────────────────────────────────┐
│                                                      │
│  Intel iGPU (renders everything)                    │
│         │                                            │
│         ├──► eDP-1 (laptop) ✓ Direct                │
│         │                                            │
│         └──► [Frame Copy] ──► NVIDIA dGPU           │
│                                    │                 │
│                                    └──► HDMI-A-5     │
│                                         (external)   │
│                                                      │
│  Overhead: ~5-15ms latency per frame copy           │
└──────────────────────────────────────────────────────┘

Impacts

• ❌ Additional latency: 5-15ms per frame copy
• ❌ NVIDIA always active: Doesn't enter deep power-save
• ❌ Higher power consumption: ~5-10W extra even without gaming
• ⚠️ Possible tearing: If VRR isn't properly configured

Solutions and Trade-offs

✅ Option 1: Keep Reverse PRIME (Current Configuration)

Advantages:

• Better battery life than NVIDIA full-time
• Wayland works better with Intel as compositor
• NVIDIA available for gaming with prime-run

Disadvantages:

• Frame copies Intel→NVIDIA
• ~5-15ms latency on external monitor
• NVIDIA never completely turns off

When to use:

• Working primarily on battery
• Not gaming on external monitor
• Prioritize efficiency over minimal latency

---

⚡ Option 2: NVIDIA as Primary GPU

Change to have NVIDIA render everything (including compositor).

Required configuration:

# In environment.conf, change to:
env = LIBVA_DRIVER_NAME,nvidia
env = GBM_BACKEND,nvidia-drm
env = __GLX_VENDOR_LIBRARY_NAME,nvidia
env = WLR_NO_HARDWARE_CURSORS,1

# Remove:
# env = __NV_PRIME_RENDER_OFFLOAD,1

Advantages:

• No frame copies for external monitor
• Minimal latency on HDMI-A-5
• Better for fulltime gaming

Disadvantages:

• ❌ MUCH higher consumption (+15-25W even at idle)
• ❌ Fans always active under Wayland
• ❌ Worse Wayland support on NVIDIA
• ❌ Battery drains 2-3x faster

When to use:

• External monitor always connected
• Intensive gaming on external monitor
• Laptop always plugged into power

---

🎯 Option 3: Dynamic Hybrid Mode (Recommended)

Use different profiles depending on usage:

For Work/Battery (Current config)

# Already configured - uses Intel for compositor
hyprctl reload

For Gaming/Performance

# Script to temporarily switch to NVIDIA primary
prime-run hyprland  # Or configure separate Hyprland session

---

Current Applied Configuration

Your system is configured for Option 1 (Optimized Reverse PRIME):

environment.conf

• Intel handles VA-API (video decode)
• NVIDIA configured to present on physical HDMI port
• __NV_PRIME_RENDER_OFFLOAD variables active
• Hardware cursors enabled (test for glitches)

monitors.conf

• eDP-1 explicitly configured
• HDMI-A-5 with auto-detect
• Reverse PRIME flow documented

Verifying Performance

1. Check which GPU Hyprland uses

# See active GPU for Hyprland
hyprctl systeminfo | grep -i "gpu"

# Or verify processes:
nvidia-smi  # Check if Hyprland appears here

2. Check input latency

# On external monitor, move windows quickly
# Feel if there's noticeable lag vs laptop screen

3. Measure power consumption

# See power consumption
cat /sys/class/power_supply/BAT*/power_now
# Lower number = better (values in µW)

# See NVIDIA GPU usage
nvidia-smi dmon

4. If you see cursor glitches on external monitor

# Uncomment in environment.conf:
env = WLR_NO_HARDWARE_CURSORS,1

Recommendations

For your case (2 monitors, hybrid laptop)

1. Keep current configuration (Reverse PRIME) for daily use
2. Monitor latency on external monitor
3. If you notice annoying lag: Consider switching to NVIDIA primary
4. For gaming: Use prime-run or launch games with NVIDIA variables

Signs you should switch to NVIDIA primary

• ✓ Noticeable lag/tearing on external monitor
• ✓ Frequently gaming on external monitor
• ✓ Laptop always plugged into power
• ✓ Don't care about fan noise

Keep Reverse PRIME if

• ✓ Regularly use battery
• ✓ Current lag is imperceptible
• ✓ Prioritize silence/low temperature
• ✓ Not doing intensive gaming

Troubleshooting

Problem: External monitor has noticeable lag

Solution: Switch to NVIDIA primary (Option 2)

Problem: Cursor corrupts on external monitor

Solution: Enable WLR_NO_HARDWARE_CURSORS,1

Problem: NVIDIA doesn't release memory

Solution:

# Kill persistent NVIDIA processes
sudo systemctl restart display-manager

Problem: Tearing on external monitor

Solution:

# In hyprland.conf, verify:
misc {
    vrr = 1  # Variable Refresh Rate
    no_direct_scanout = false
}

Useful Commands

# See active GPUs
lspci | grep -E "VGA|3D"

# See processes using NVIDIA
nvidia-smi

# See monitors in Hyprland
hyprctl monitors

# See DRM outputs
drm_info | grep -A5 "Connector"

# See which GPU a specific window uses
hyprctl clients | grep -A10 "class:"

# Launch specific app on NVIDIA
prime-run <app>
__NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia <app>

Performance States Explained

NVIDIA GPUs have different performance states (P-states):

P-State	Mode	Power Usage	Use Case
P0	Maximum Performance	~50-55W	Gaming, Heavy Compute
P2	Balanced	~20-30W	Video Editing
P5	Low Power	~5-10W	Display Output Only
P8	Idle (not achievable with display)	~1-2W	No display connected

In Reverse PRIME mode with external monitor, NVIDIA stays at P5 (5W) minimum.

Expected Performance Metrics

Battery Life Impact

• Before optimization: ~15-25W additional GPU consumption
• After (Reverse PRIME): ~5W (3-5x better battery duration)
• NVIDIA Primary: ~20-30W (worst battery life)

Latency

• Laptop Monitor (eDP-1): 0ms overhead ✓
• External Monitor (HDMI-A-5): ~5-10ms overhead (frame copy)

Gaming

Use prime-run to force full NVIDIA:

prime-run steam
prime-run lutris
prime-run godot

Advanced: Creating Profile Scripts

Create profile switching scripts for different scenarios:

~/.local/bin/dots-gpu-mode-battery

#!/usr/bin/env bash
# Switch to battery-optimized mode (Intel primary)

# Copy environment.conf with Intel settings
# Reload Hyprland
hyprctl reload
notify-send "GPU Mode" "Switched to Battery Mode (Intel primary)"

~/.local/bin/dots-gpu-mode-performance

#!/usr/bin/env bash
# Switch to performance mode (NVIDIA primary)

# Copy environment.conf with NVIDIA settings
# Reload Hyprland
hyprctl reload
notify-send "GPU Mode" "Switched to Performance Mode (NVIDIA primary)"

References

• Hyprland NVIDIA Guide
• Arch Wiki: PRIME
• NVIDIA Wayland Support
• Kernel DRM PRIME Documentation

Related Documentation

• Hardware - General hardware configuration
• Hardware-nvidia-troubleshooting - NVIDIA-specific issues
• Hyprland-Setup - Hyprland configuration guide
• Window-Managers - Window manager configurations