[mangeshraut712]

Closes #3215.

Summary

Updated simpleP2P, simpleMultiGpu, and multiGPUGradientAverage to size device enumeration with len(Device.get_all_devices()), which follows CUDA runtime visibility including CUDA_VISIBLE_DEVICES. Corrected the two affected READMEs and added a focused regression test. Kept system.get_num_devices() unchanged for NVML system inventory use.

Files

• samples/cuda_core/simpleP2P/simpleP2P.py
• samples/cuda_core/simpleP2P/README.md
• samples/cuda_core/simpleMultiGpu/simpleMultiGpu.py
• samples/cuda_core/simpleMultiGpu/README.md
• samples/cuda_core/multiGPUGradientAverage/multiGPUGradientAverage.py
• cuda_core/tests/example_tests/test_sample_verification.py

Tip

b462a85c70f6184c928a21dff11a19f50bd49d91

Test plan

• git diff --check
• AST/parse check on touched sample + test modules
• Await NVIDIA runner CI after copy-pr-bot / metadata gate clears

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[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	⚠️ Failed 2026-10-25T21:47:17.603005Z We couldn’t complete this review. Comment @codex review to try again.	b462a85	PR opened

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[coderabbitai]

📝 Summary

Summary by CodeRabbit

• Updates
  • Multi-GPU samples now count devices visible to CUDA, so their reported count reflects CUDA_VISIBLE_DEVICES settings rather than all CUDA-capable GPUs.
  • Samples still require at least two visible devices to run multi-GPU workflows; they skip those workflows when fewer are available.
  • Updated sample documentation to describe device visibility, device counting, and the minimum-device requirement.

The three multi-GPU samples now count CUDA-visible devices with len(Device.get_all_devices()) instead of system.get_num_devices(). Their README text and a parametrized test were updated to reflect and check this API.

Changes: CUDA-visible device enumeration

Layer / File(s)	Summary
Update multi-GPU sample device counting samples/cuda_core/simpleP2P/simpleP2P.py, samples/cuda_core/simpleMultiGpu/simpleMultiGpu.py, samples/cuda_core/multiGPUGradientAverage/multiGPUGradientAverage.py, samples/cuda_core/simpleP2P/README.md, samples/cuda_core/simpleMultiGpu/README.md, cuda_core/tests/example_tests/test_sample_verification.py	All three samples count devices with len(Device.get_all_devices()). The README text describes the API, and the test checks that the samples use it instead of get_num_devices.

Assessment against linked issues

Objective	Addressed	Explanation
Count devices available to the process in the three multi-GPU samples [#3215]	✅
Update the README descriptions of device counting [#3215]	✅

Possibly related PRs

• NVIDIA/cuda-python#3198 — Both changes use process-visible device enumeration. This PR applies it to sample device counts.
• NVIDIA/cuda-python#3126 — Both changes concern visible-device mapping. This PR changes sample device counts.

Suggested reviewers: danielfrg

Priority: Normal

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: Low · up to 0f119

The samples work with visible-device enumeration, but the simpleP2P README should be updated to match the output before merging.

Finishing Touches: 💡 1

🛠️ Fix failing CI checks: 💡

• Commit to this branch
• Create a new PR

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

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[mangeshraut712]

I checked the review feedback and local lint. The Codex review did not publish a concrete finding and CodeRabbit reported no actionable comments; I only fixed the Ruff formatting violation in the sample-verification test.

[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to GitHub limitations.

⚠️ Outside diff range comments (1)

Minor · 📐 Maintainability & Code Quality · README.md:135

samples/cuda_core/simpleP2P/README.md:135
📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

suggestion: Update the expected output label.

The sample now prints CUDA-visible device count, but the README still documents CUDA-capable device count. Update the expected output to match the sample.

Suggested fix

-CUDA-capable device count: 2
+CUDA-visible device count: 2

---

Review info

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• Source mode: Auto
• Repository: NVIDIA/cuda-python
• Branch: main
• File: .coderabbit.yaml
• Commit: 590a8bf
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Commits

Reviewing files that changed from the base of the PR and between 10d7010 and 0f1192a.

Files selected for processing: 3

• samples/cuda_core/multiGPUGradientAverage/multiGPUGradientAverage.py
• samples/cuda_core/simpleMultiGpu/simpleMultiGpu.py
• samples/cuda_core/simpleP2P/simpleP2P.py

Files with no reviewable changes: 2

• samples/cuda_core/multiGPUGradientAverage/multiGPUGradientAverage.py
• samples/cuda_core/simpleP2P/simpleP2P.py

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