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| 1 | +# System Performance Tuning Guide |
| 2 | + |
| 3 | +This guide provides recommendations for optimizing system performance when running SYCL and Unified Runtime benchmarks. |
| 4 | +For framework-specific information, see [README.md](README.md) and [CONTRIB.md](CONTRIB.md). |
| 5 | + |
| 6 | +## Table of Contents |
| 7 | + |
| 8 | +- [Overview](#overview) |
| 9 | +- [System Configuration](#system-configuration) |
| 10 | +- [CPU Tuning](#cpu-tuning) |
| 11 | +- [GPU Configuration](#gpu-configuration) |
| 12 | +- [Driver and Runtime Optimization](#driver-and-runtime-optimization) |
| 13 | +- [Environment Variables](#environment-variables) |
| 14 | + |
| 15 | +## Overview |
| 16 | + |
| 17 | +Performance benchmarking requires a stable and optimized system environment to produce reliable and reproducible results. This guide covers essential system tuning steps for reducing run-to-run variance in benchmark results and enabling consistent results across different runs. |
| 18 | + |
| 19 | +## System Configuration |
| 20 | + |
| 21 | +### Kernel Parameters |
| 22 | + |
| 23 | +Add the following to `/etc/default/grub` in `GRUB_CMDLINE_LINUX`: |
| 24 | + |
| 25 | +```bash |
| 26 | +# Disable CPU frequency scaling |
| 27 | +intel_pstate=disable |
| 28 | + |
| 29 | +# Isolate CPUs for benchmark workloads (example: reserve cores 2-7), preventing other processes |
| 30 | +# from using them. |
| 31 | +isolcpus=2-7 |
| 32 | + |
| 33 | +# Set CPU governor to performance |
| 34 | +sudo cpupower frequency-set --governor performance |
| 35 | + |
| 36 | +# Check current governor |
| 37 | +sudo cpupower frequency-info |
| 38 | + |
| 39 | +# Example complete line: |
| 40 | +GRUB_CMDLINE_LINUX="intel_pstate=disable isolcpus=2-7" |
| 41 | +``` |
| 42 | + |
| 43 | +Update GRUB and reboot: |
| 44 | +```bash |
| 45 | +sudo update-grub |
| 46 | +sudo reboot |
| 47 | +``` |
| 48 | + |
| 49 | +## CPU Tuning |
| 50 | + |
| 51 | +### CPU Frequency Scaling |
| 52 | + |
| 53 | +The performance governor ensures that the CPU runs at maximum frequency. |
| 54 | +```bash |
| 55 | +# Set performance governor for all CPUs |
| 56 | +sudo cpupower frequency-set --governor performance |
| 57 | +``` |
| 58 | + |
| 59 | +### CPU Affinity |
| 60 | + |
| 61 | +Bind benchmark processes to specific CPU cores to reduce context switching and improve cache locality. |
| 62 | +Make sure that isolated CPUs are located on the same NUMA node as the GPU being used. |
| 63 | +```bash |
| 64 | +# Run benchmark on specific CPU cores |
| 65 | +taskset -c 2-7 ./main.py ~/benchmarks_workdir/ --sycl ~/llvm/build/ |
| 66 | +``` |
| 67 | + |
| 68 | +## GPU Configuration |
| 69 | + |
| 70 | +### GPU Frequency Control |
| 71 | +Setting the GPU to run at maximum frequency can significantly improve benchmark performance and stability. |
| 72 | + |
| 73 | +First, find which card relates to the GPU you want to tune (e.g., card1). List of known Device IDs for |
| 74 | +Intel GPU cards can be found at https://dgpu-docs.intel.com/devices/hardware-table.html#gpus-with-supported-drivers. |
| 75 | +```bash |
| 76 | +# Print card1 Device ID |
| 77 | +cat /sys/class/drm/card1/device/vendor # Should be 0x8086 for Intel |
| 78 | +cat /sys/class/drm/card1/device/device # Device ID |
| 79 | +``` |
| 80 | + |
| 81 | +Verify the max frequency is set to the true max. For Arc B580, the maximum frequency is 2850 MHz. To see this value, run “cat /sys/class/drm/card1/device/tile0/gt0/freq0/max_freq”. If the above value is not equal to the max frequency, set it as such: |
| 82 | +```bash |
| 83 | +# Arc B580 (Battlemage) |
| 84 | +echo 2850 > /sys/class/drm/card1/device/tile0/gt0/freq0/max_freq |
| 85 | + |
| 86 | +# Set the min frequency to the max frequency, so it is fixed |
| 87 | +echo 2850 > /sys/class/drm/card1/device/tile0/gt0/freq0/min_freq |
| 88 | +``` |
| 89 | + |
| 90 | +```bash |
| 91 | +# Check GPU frequencies for GPU Max 1100 (Ponte Vecchio) |
| 92 | +cat /sys/class/drm/card1/gt_max_freq_mhz |
| 93 | +cat /sys/class/drm/card1/gt_min_freq_mhz |
| 94 | + |
| 95 | +# Set maximum GPU frequency |
| 96 | +max_freq=$(cat /sys/class/drm/card1/gt_max_freq_mhz) |
| 97 | +echo $max_freq | sudo tee /sys/class/drm/card1/gt_min_freq_mhz |
| 98 | +``` |
| 99 | + |
| 100 | +The result can be verified using tools such as oneprof or unitrace to track frequency over time for some arbitrary benchmark (many iterations of a small problem size is recommended). The frequency should remain fixed assuming thermal throttling does not occur. |
| 101 | + |
| 102 | +## Driver version |
| 103 | +Make sure you are using the latest driver (Ubuntu) |
| 104 | +```bash |
| 105 | +sudo apt update && sudo apt upgrade |
| 106 | +``` |
| 107 | + |
| 108 | +## Environment Variables |
| 109 | + |
| 110 | +### Level Zero Environment Variables |
| 111 | +Use GPU affinity to bind benchmarks to a specific GPU. Use CPUs from the same NUMA node as the GPU to reduce latency. |
| 112 | +```bash |
| 113 | +export ZE_AFFINITY_MASK=0 |
| 114 | +``` |
| 115 | + |
| 116 | +### SYCL Runtime Variables |
| 117 | +For consistency, limit available devices to a specific gpu runtime. For Level Zero, it is recommended to use v2 version of the runtime library. |
| 118 | +```bash |
| 119 | +export ONEAPI_DEVICE_SELECTOR="level_zero:gpu" |
| 120 | +export SYCL_UR_USE_LEVEL_ZERO_V2=1 |
| 121 | +``` |
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