LuxMark 4.0 — What’s New and How It Affects Performance

LuxMark Benchmark: Fast GPU Rendering Scores and TipsLuxMark is an open-source benchmarking tool designed to measure the OpenCL rendering performance of GPUs and CPUs using LuxCoreRender kernels. It provides a straightforward way to compare hardware across different vendors and driver versions by rendering standardized scenes and reporting scores that reflect throughput and rendering efficiency. This article explains how LuxMark works, how to interpret its scores, how to run meaningful tests, and practical tips to get the most accurate and useful results from your benchmarking sessions.

What LuxMark measures

LuxMark renders predefined test scenes (and custom scenes when desired) using LuxCoreRender’s path-tracing kernels implemented in OpenCL. The benchmark reports a numeric score that represents the number of samples per second or a related throughput metric produced by the rendering kernel. Higher scores indicate faster rendering performance. Because it uses OpenCL, LuxMark can test GPUs from different vendors (NVIDIA, AMD, Intel) and CPUs that support OpenCL.

Key facts:

• LuxMark uses OpenCL-based kernels from LuxCoreRender to compute physically based path-traced images.
• Scores are comparative throughput numbers: higher is better.
• Results depend on drivers, OpenCL runtime, and scene selection, not just raw hardware specs.

Common LuxMark scenes and their characteristics

LuxMark includes several built-in scenes that stress different aspects of rendering hardware:

• Ballroom: a complex scene with many light bounces and geometry — stresses memory bandwidth and compute.
• Whispering-Gallery: heavy use of global illumination and many small light sources — stresses compute and ray traversal.
• Simple scenes (e.g., quick test renders): useful for quick sanity checks and driver comparisons.

Choice of scene affects which hardware features matter most: memory bandwidth and cache behavior matter more for geometry- and texture-heavy scenes; compute throughput matters more for shader-heavy or high-sample workloads.

Preparing for a fair benchmark

To get meaningful, comparable results, control the testing environment:

• Use the same scene, resolution, and number of samples when comparing hardware.
• Close background applications, especially those that use GPU acceleration (web browsers, video players, games).
• Use reliable power settings:
  • On laptops, use the high-performance power plan and keep the unit plugged in.
  • On desktops, ensure the GPU power limit is not artificially constrained.
• Keep the system thermals consistent:
  • Run tests in a cool environment.
  • If possible, allow the GPU to reach a stable temperature or restart between runs to avoid thermal throttling variability.
• Use up-to-date drivers and OpenCL runtimes, but document driver versions to maintain reproducibility.
• Run multiple passes and report median or average results to reduce variance.

How to run LuxMark

1. Download the latest LuxMark release from the official project page or repository.
2. Install or extract the package and ensure the OpenCL drivers for your device are installed.
3. Launch LuxMark and choose:
   • Scene (Ballroom, Whispering-Gallery, etc.).
   • Device (select a specific GPU or CPU).
   • Resolution and number of samples or render time (depending on benchmark settings).
4. Start the benchmark and wait for the run to complete. LuxMark will output a score when finished.
5. Repeat runs and record results, noting driver versions, OS, power state, and ambient temperature.

Interpreting LuxMark scores

• Compare scores only when test parameters match exactly (scene, resolution, sample count, device selection).
• Scaling behavior:
  • Multi-GPU scaling is often sublinear due to CPU and PCIe overhead; expect diminishing returns as GPUs increase.
  • CPU scores will generally be far lower than modern GPUs for path-tracing workloads but are useful for cross-platform comparisons.
• Watch for anomalies:
  • A sudden drop or increase in score after driver updates may indicate changes in OpenCL runtime optimizations or regressions.
  • If a GPU’s score is much lower than expected from similar hardware, check thermal throttling, power limits, and background processes.

Tips to improve LuxMark scores (and real-world render times)

• Update GPU drivers and OpenCL runtimes. Vendors regularly improve compute shader and OpenCL performance.
• Use manufacturer-tuned drivers: for some GPUs, workstation drivers (e.g., NVIDIA Studio/QUADRO drivers, AMD Pro) may offer better stability or performance for compute workloads.
• Increase GPU power limits where possible (desktop GPUs), but watch thermals.
• Optimize system memory speed and timings — some scenes benefit from faster system RAM and lower latency.
• Use GPUs with larger VRAM for heavy scenes to avoid fallback to system memory or failed allocations.
• For multi-GPU setups:
  • Ensure sufficient PCIe lanes and bandwidth (avoid mixing x16 with x4 slots under heavy loads).
  • Use the same GPU model and driver for better load balancing.
• For laptops:
  • Keep the device plugged in and on a high-performance power plan.
  • Consider undervolting CPU/GPU to reduce thermal throttling while preserving performance.
• In LuxCoreRender scenes used outside LuxMark, reduce unnecessary texture sizes, simplify geometry where possible, and use denoising to lower required samples.

Advanced considerations

• OpenCL vs. vendor-specific alternatives: LuxCoreRender’s OpenCL kernels make LuxMark broadly compatible, but vendor-specific frameworks (CUDA for NVIDIA, ROCm for AMD) may be faster in dedicated renderers that use them; LuxMark is best for cross-vendor OpenCL comparisons.
• Driver regressions and optimizations can change results across updates — always record exact driver/runtime versions with benchmark results.
• For professional usage, pair LuxMark results with real workload tests (your own scenes) to understand actual performance in context.
• Benchmark reproducibility: publish configuration details (OS, kernel/driver versions, BIOS settings, power plan, background tasks) when sharing scores publicly.

Example result reporting format

When recording LuxMark runs, include:

• Device model, driver version, and OpenCL runtime.
• Scene name, resolution, and sample count/time limit.
• Ambient temperature and whether the run was repeated — report median of 3–5 runs.
• Any system tweaks (power limit raised, undervolt applied).

Example (concise):

• GPU: NVIDIA RTX 4080 — Driver 554.XX — OpenCL runtime X.Y
• Scene: Ballroom — 1920×1080 — 1000 samples
• Score: 14,320 (median of 3 runs)
• Notes: Power limit +10%, ambient 22°C

Conclusion

LuxMark is a practical, cross-vendor benchmark for OpenCL-based path-tracing performance. It’s most useful when tests are controlled, documented, and paired with real-world rendering workloads. Small system tweaks (drivers, power limits, thermals) can noticeably affect scores; for meaningful comparisons, keep variables consistent and report full test configurations.