[STF] Name green context data places by handle and support VMM mem_create by caugonnet · Pull Request #9706 · NVIDIA/cccl

caugonnet · 2026-07-04T09:58:22Z

Summary

green_ctx_data_place_impl::to_string() now includes the green context handle in addition to the device id, so two green contexts on the same device produce distinct names (previously they were indistinguishable).
Override green_ctx_data_place_impl::mem_create() to allocate device-pinned physical memory bound to the green context's device, enabling green context data places to back VMM (localized array) allocations.

Tests

New co-located unittest in green_context.cuh (green context data_place to_string distinguishes contexts on the same device) asserting the name embeds dev=/ctx= and differs between two green contexts on the same device, while being stable for the same context.
Extended cudax/test/places/data_place_vmm.cu with test_green_ctx_vmm_allocation() which exercises the green context mem_create() override end-to-end: create physical memory, reserve/map VA, set device access, run init/check kernels, and verify.

Test plan

ninja cudax.test.places.data_place_vmm builds and runs green (CTK 13.0, local GPU).
ninja cudax.test.places.unittest_headers.__places.exec.green_context builds and runs green.
pre-commit (clang-format, codespell, ...) passes on both files.

Green context data places on the same device were previously indistinguishable by name and could not back VMM (localized array) allocations. Include the green context handle in green_ctx_data_place_impl::to_string() and override mem_create() to allocate device-pinned physical memory bound to the green context's device. Add a co-located unittest verifying to_string() distinguishes different green contexts on the same device, and extend data_place_vmm.cu to exercise the green_ctx mem_create() override through the full VMM map/access/kernel path.

copy-pr-bot · 2026-07-04T09:58:25Z

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coderabbitai · 2026-07-04T10:02:22Z

No actionable comments were generated in the recent review. 🎉

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Reviewing files that changed from the base of the PR and between f07a610 and 0f1e695.

📒 Files selected for processing (1)

cudax/include/cuda/experimental/__places/exec/green_context.cuh

🚧 Files skipped from review as they are similar to previous changes (1)

cudax/include/cuda/experimental/__places/exec/green_context.cuh

📝 Walkthrough

Summary by CodeRabbit

New Features
- Added green-context–aware mem_create support for CUDA VMM workflows.
- Introduced a CUDA VMM test that allocates, reserves/maps virtual memory, sets device access, and validates mapped memory using green contexts.
Bug Fixes
- Improved green-context string representation to include both device ordinal and the specific context identifier, avoiding collisions when multiple contexts share a device.
- Ensured the same green context produces consistent, repeatable to_string() output.

Walkthrough

Adds green-context-aware pinned memory creation, updates place naming to include the green context handle, and extends VMM coverage with a green-context allocation path.

Changes

Green Context mem_create Support

Layer / File(s)	Summary
Context id, naming, and allocation `cudax/include/cuda/experimental/__places/exec/green_context.cuh`	Adds a `CUgreenCtx` ID helper, updates `to_string()` to include `dev=` and `ctx=`, adds `mem_create()` for pinned device allocation, and removes the earlier in-file ID helper definitions.
to_string unit test `cudax/include/cuda/experimental/__places/exec/green_context.cuh`	A unit test verifies that green-context places on the same device differ by context, include `dev=0` and `ctx=`, and reproduce for the same context.
Green context VMM allocation test `cudax/test/places/data_place_vmm.cu`	Adds a CTK-gated green-context VMM test that uses `mem_create`, VMM reserve/map/access, kernel launches, host validation, and cleanup; also adds launch error checks, conditional includes, and wires the test into `main()`.

Related PRs: None specified.
Suggested labels: review_needed_senior_swe, review_depth_deep
Suggested reviewers: None specified.

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coderabbitai

Actionable comments posted: 2

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📥 Commits

Reviewing files that changed from the base of the PR and between 3bf2e5f and 66250f5.

📒 Files selected for processing (2)

cudax/include/cuda/experimental/__places/exec/green_context.cuh
cudax/test/places/data_place_vmm.cu

caugonnet · 2026-07-04T10:03:04Z

/ok to test c331ae8

Add cuda_try(cudaGetLastError()) after each init/check kernel launch so a non-sticky launch failure cannot silently leave the result flag at zero and mask a failing EXPECT. Applied consistently across the device, multi-segment, and green context VMM tests.

caugonnet · 2026-07-04T10:58:29Z

/ok to test f07a610

davebayer · 2026-07-04T18:17:33Z

  {
-    return "green_ctx(dev=" + ::std::to_string(view_.devid) + ")";
+    return "green_ctx(dev=" + ::std::to_string(view_.devid)
+         + ", ctx=" + ::std::to_string(reinterpret_cast<::std::uintptr_t>(view_.g_ctx)) + ")";


Wouldn't make sense to return ctx=/*green-context-id*/ that can be queried by cuGreenCtxGetId?

Agreed, that's better — done in 0f1e695. to_string() now emits ctx=<green-context-id> using the queryable unique id (via the existing get_cuda_context_id helper, i.e. cuCtxFromGreenCtx + cuCtxGetId) instead of the raw handle pointer. This also matches the naming already used by the green-context exec_place. I reused that helper rather than calling cuGreenCtxGetId directly to stay compatible across the CTK >= 12.4 range the header supports; I hoisted the helper overloads above the class so the inline to_string() can see them.

Use the green context's queryable unique id (via cuCtxFromGreenCtx + cuCtxGetId, exposed by the existing get_cuda_context_id helper) in green_ctx_data_place_impl::to_string() instead of the raw handle pointer. This mirrors the exec_place green context naming and gives a stable, meaningful identifier. The helper overloads are hoisted above the class so the inline to_string() can see them.

caugonnet · 2026-07-05T16:36:14Z

/ok to test 0f1e695

github-actions · 2026-07-05T17:44:32Z

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caugonnet requested a review from a team as a code owner July 4, 2026 09:58

caugonnet requested a review from andralex July 4, 2026 09:58

github-project-automation Bot added this to CCCL Jul 4, 2026

github-project-automation Bot moved this to Todo in CCCL Jul 4, 2026

cccl-authenticator-app Bot moved this from Todo to In Review in CCCL Jul 4, 2026

caugonnet changed the title ~~Name green context data places by handle and support VMM mem_create~~ [STF] Name green context data places by handle and support VMM mem_create Jul 4, 2026

coderabbitai Bot reviewed Jul 4, 2026

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Comment thread cudax/test/places/data_place_vmm.cu

Comment thread cudax/test/places/data_place_vmm.cu

Merge branch 'main' into green-ctx-name-and-vmm-mem-create

c331ae8

caugonnet self-assigned this Jul 4, 2026

caugonnet added the stf Sequential Task Flow programming model label Jul 4, 2026

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[STF] Name green context data places by handle and support VMM mem_create#9706

[STF] Name green context data places by handle and support VMM mem_create#9706
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caugonnet commented Jul 4, 2026

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