Runtime Requirements

• NVIDIA Nsight Compute from CUDA Toolkit 13.3 Update 1 or later: nsight-python uses the NVIDIA Nsight Compute CLI (ncu 2026.2.1+). Ensure ncu is installed and available on the system path.

Import Ordering

import nsight must come before:

• CUDA initialization: You must import nsight before any operation that initializes CUDA (e.g. torch.cuda.init()). If CUDA is initialized first, NVIDIA Nsight Compute cannot attach correctly and profiling fails (commonly with NV_INJ_ERROR_NOT_INITIALIZED).

  Recommendation: Place import nsight at the top of your script, before all CUDA-related imports and calls.

• Any NVTX API calls: nsight-python updates NVTX_INJECTION64_PATH at import time. Any NVTX usage before import nsight will cause NVTX annotation ranges to be missed and profiling results to be incomplete.