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Multi-GPU

Auto-detection

By default, Matcha detects all NVIDIA GPUs on the machine and sums power readings across all of them. No flags needed.

ALL GPUS (DEFAULT)$matcha run torchrun -​-standalone -​-nproc_per_node=8 train.py# auto-detects all 8 GPUs, sums power across themSPECIFIC GPUS$matcha run -​-gpus 0,1,2,3 torchrun -​-nproc_per_node=4 train.py# only polls GPUs 0 through 3OUTPUT (8xH100)matcha_energy gpus:8x NVIDIA H100 80GB HBM3 total:2920000J (811Wh)

How it works

Every 100ms, Matcha reads nvmlDeviceGetPowerUsage for each monitored GPU and sums the values into a single power reading. Trapezoidal integration then computes total energy from these summed readings.

avg_power and peak_power in the output reflect the aggregate across all monitored GPUs. For example, 8 GPUs each drawing 500W would show avg_power:4000W.