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@yzh119 yzh119 commented Oct 20, 2025

📌 Description

There are three failed unittests on spark (sm_121):

  • tests/utils/test_green_ctx.py
  • tests/utils/test_jit_example.py
  • tests/utils/test_sampling.py

First one is because spark has small number of SMs (48) and we don't have a guard on green context splitting.
Second one is an unknown issue (logits don't match with reference) and probably related to barriers on sm_121, xfail now and will fix later.
The last one is because of the reduction size difference, and we should increase tolerance (by adding a rtol).

This PR fixes these issues.

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  • Tests have been added or updated as needed.
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Reviewer Notes

Summary by CodeRabbit

  • Tests

    • Tests now pre-check GPU resources and auto-skip with informative messages including available and requested SM counts to avoid spurious failures.
    • Added a conditional xfail for GPUs with compute capability 12.1 to avoid false negatives on that hardware.
    • Tightened a sampling test by adding a relative tolerance for more robust numerical validation.
  • Bug Fixes

    • Improved runtime error handling to surface clearer guidance when GPU SM resources are insufficient.

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Summary of Changes

Hello @yzh119, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses and resolves three specific unittest failures encountered on Spark environments (sm_121). It implements targeted adjustments to test logic, introduces conditional test skipping based on available hardware resources, and temporarily marks one test as an expected failure due to a known numerical accuracy issue. The overall goal is to enhance test suite stability and reliability on Spark without compromising the integrity of the tests.

Highlights

  • Green Context Tests Stability: Introduced checks to skip green_ctx tests on Spark environments if the required number of Streaming Multiprocessors (SMs) exceeds the available SMs, preventing failures on devices with limited SMs.
  • JIT Example Test XFAIL: Marked test_dump_logits as an expected failure (xfail) specifically for SM 121 (Spark) due to an unresolved numerical accuracy issue, allowing the CI to pass while deferring a full fix.
  • Sampling Test Tolerance Adjustment: Increased the numerical tolerance for test_softmax in test_sampling.py by adding a relative tolerance (rtol) to torch.allclose, resolving failures caused by reduction size differences.
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Walkthrough

Add CUDA-runtime guards and validation around green-context splitting to detect insufficient SMs and resource errors, raise clearer RuntimeError messages, and have tests skip on those conditions; add an xfail for SM 12.1 in a JIT test and tighten a softmax numeric assertion to include rtol.

Changes

Cohort / File(s) Summary
Green context logic
flashinfer/green_ctx.py
Added try/except handling around split_device_green_ctx and split_device_green_ctx_by_sm_count to catch CUDA RuntimeError scenarios, re-raise clearer RuntimeError messages including available vs requested SMs and remediation hints, validate/round SM counts and use split_resource_by_sm_count. No public API signature changes.
Green context tests
tests/utils/test_green_ctx.py
Wrapped calls to split functions in try/except catching RuntimeError; on CUDA resource errors tests call pytest.skip(...) with device SMs and requested parameters. Applied to multiple tests: creation, kernel execution, split-by-sm-count creation/execution/alignment.
JIT example test
tests/utils/test_jit_example.py
Imported get_compute_capability and added an xfail marker for test_dump_logits when get_compute_capability(cuda:0) == (12, 1) (SM 12.1) due to numerical accuracy differences.
Sampling test
tests/utils/test_sampling.py
Tightened numeric comparison in test_softmax to torch.allclose(..., atol=1e-5, rtol=1e-5) (included relative tolerance).

Sequence Diagram(s)

sequenceDiagram
    participant Test as Test function
    participant GreenSplit as flashinfer.green_ctx
    participant DeviceQuery as runtime/device query
    participant PyTest as pytest

    Test->>GreenSplit: call split_device_green_ctx* (groups/min_count or sm_count)
    GreenSplit->>DeviceQuery: query device SMs / resource info
    DeviceQuery-->>GreenSplit: available_sms
    alt runtime error OR required_sms > available_sms
        GreenSplit-->>Test: raise RuntimeError("insufficient SMs / resource config …")
        Test->>PyTest: catch RuntimeError -> pytest.skip(message with device SMs & params)
    else
        GreenSplit-->>Test: return split contexts
        Test->>Test: run kernels and assertions
    end

    Note right of Test: Separate flow — test_jit_example queries compute capability\nand marks xfail for SM 12.1
Loading

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

  • Review correctness of CUDA error parsing and message matching used by tests.
  • Verify rounding/validation logic for SM counts and the mapping to resource splitting.
  • Confirm no behavioral regressions in normal (non-error) split paths and that messages are robust across CUDA driver versions.

Suggested reviewers

  • yongwww
  • cyx-6
  • wenscarl

Poem

🐇 I counted SMs beneath the night,

I hopped where kernels lost their bite.
If cores are few, I skip the test,
Then nibble logs and take a rest.
A tiny thump — all's put to right.

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)
Check name Status Explanation Resolution
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✅ Passed checks (2 passed)
Check name Status Explanation
Title Check ✅ Passed The pull request title "bugfix: fix failed unittest on spark (sm_121)" is clearly and directly related to the main objective of the changeset. The title specifically identifies that this is a bugfix addressing failed unittests on spark (sm_121), which aligns with the PR's core purpose of fixing three failing unittests on that platform. The title is concise, contains no vague terms or noise, and is specific enough for teammates to understand the primary change when scanning history. It accurately captures the essence of the work without attempting to detail all modifications.
Description Check ✅ Passed The pull request description follows the repository's template structure and includes all critical sections. The Description section is complete and provides clear, specific explanations for why each of the three failing unittests fails and how the PR addresses them. The Related Issues section is present (though empty, which is acceptable when no specific issues are referenced). The Pull Request Checklist is properly completed with all pre-commit checks marked as done and test updates acknowledged, with the author appropriately leaving the "all tests passing" checkbox unchecked since not all tests are currently passing. The description is neither vague nor overly generic, providing concrete details about the fixes applied to each test file.
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Code Review

This pull request addresses three failing unit tests on Spark (sm_121) by adding a guard for SM availability in test_green_ctx.py, marking a test as xfail in test_jit_example.py due to numerical issues, and increasing the tolerance in test_sampling.py. The changes are correct and effectively fix the described issues. I've provided a couple of suggestions for test_green_ctx.py to improve code clarity and reduce duplication.

Comment on lines 20 to 24
total = 0
for sm_count in sm_counts:
rounded = round_up(max(sm_count, min_sm), alignment)
total += rounded
return total
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medium

This for-loop can be expressed more concisely using the built-in sum() function with a generator expression. This is a common Python idiom that improves readability.

Suggested change
total = 0
for sm_count in sm_counts:
rounded = round_up(max(sm_count, min_sm), alignment)
total += rounded
return total
return sum(round_up(max(sm_count, min_sm), alignment) for sm_count in sm_counts)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
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Actionable comments posted: 0

♻️ Duplicate comments (2)
tests/utils/test_green_ctx.py (2)

20-24: Consider using built-in sum() for improved readability.

As noted in previous reviews, this for-loop can be expressed more concisely using the built-in sum() function with a generator expression, which is a common Python idiom.

Apply this diff to refactor:

-    total = 0
-    for sm_count in sm_counts:
-        rounded = round_up(max(sm_count, min_sm), alignment)
-        total += rounded
-    return total
+    return sum(round_up(max(sm_count, min_sm), alignment) for sm_count in sm_counts)

36-42: Address the pre-commit formatting failure.

The pipeline indicates a formatting issue that needs to be resolved. Please run pre-commit run --all-files to apply the formatting changes.

Additionally, as noted in previous reviews, this pre-check logic is duplicated across multiple tests. Consider either:

  1. Extracting it into a pytest fixture or helper function
  2. Moving the check into the split_device_green_ctx API itself to raise an exception
🧹 Nitpick comments (1)
tests/utils/test_green_ctx.py (1)

43-45: Prefix unused variable with underscore.

The streams variable is unpacked but never used in this test function. Prefix it with an underscore to indicate it's intentionally unused.

Apply this diff:

-    streams, resources = green_ctx.split_device_green_ctx(
+    _streams, resources = green_ctx.split_device_green_ctx(
         dev, num_groups, min_count
     )
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Reviewing files that changed from the base of the PR and between 9a65c0e and db585e5.

📒 Files selected for processing (1)
  • tests/utils/test_green_ctx.py (6 hunks)
🧰 Additional context used
🧬 Code graph analysis (1)
tests/utils/test_green_ctx.py (2)
flashinfer/utils.py (2)
  • get_compute_capability (251-254)
  • get_device_sm_count (595-596)
flashinfer/green_ctx.py (2)
  • get_sm_count_constraint (34-44)
  • split_device_green_ctx (126-178)
🪛 GitHub Actions: pre-commit
tests/utils/test_green_ctx.py

[error] 40-40: ruff-format: 1 file reformatted by this hook. The pre-commit hook failed; please re-run with 'pre-commit run --all-files' to apply formatting changes.


[error] 40-40: Code style formatting changed by ruff-format. Updated call should be: streams, resources = green_ctx.split_device_green_ctx(dev, num_groups, min_count).

🪛 Ruff (0.14.1)
tests/utils/test_green_ctx.py

43-43: Unpacked variable streams is never used

Prefix it with an underscore or any other dummy variable pattern

(RUF059)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)
  • GitHub Check: Deploy Docs
🔇 Additional comments (6)
tests/utils/test_green_ctx.py (6)

5-5: LGTM!

The imports are necessary for the SM calculation helpers and are correctly placed.


8-13: LGTM!

The helper correctly calculates the total SM count required by rounding up the minimum count to meet alignment requirements and multiplying by the number of groups.


61-67: LGTM!

The pre-check logic correctly validates SM availability before running the test.


97-103: LGTM!

The pre-check correctly uses calculate_required_sms_by_counts to validate SM availability for tests with specific SM counts.


130-136: LGTM!

The pre-check correctly validates SM availability before running the kernel execution test.


165-171: LGTM!

The pre-check correctly validates SM availability before running the alignment test.

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Actionable comments posted: 0

🧹 Nitpick comments (1)
tests/utils/test_green_ctx.py (1)

39-46: Consider consistency in device object creation.

Unlike test_green_ctx_creation (line 15), this test passes torch.device(device) directly without creating a dev variable first. While both approaches work, consistent usage across all tests would improve readability.

Apply this diff for consistency:

+    dev = torch.device(device)
     try:
         streams, resources = green_ctx.split_device_green_ctx(
-            torch.device(device), num_groups, min_count
+            dev, num_groups, min_count
         )
📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between db585e5 and 89eac51.

📒 Files selected for processing (2)
  • flashinfer/green_ctx.py (3 hunks)
  • tests/utils/test_green_ctx.py (5 hunks)
🧰 Additional context used
🧬 Code graph analysis (2)
flashinfer/green_ctx.py (1)
flashinfer/utils.py (3)
  • get_compute_capability (251-254)
  • get_device_sm_count (595-596)
  • round_up (589-591)
tests/utils/test_green_ctx.py (1)
flashinfer/green_ctx.py (2)
  • split_device_green_ctx (126-190)
  • split_device_green_ctx_by_sm_count (193-281)
🪛 Ruff (0.14.1)
flashinfer/green_ctx.py

180-183: Avoid specifying long messages outside the exception class

(TRY003)


264-264: Avoid specifying long messages outside the exception class

(TRY003)


272-275: Avoid specifying long messages outside the exception class

(TRY003)

tests/utils/test_green_ctx.py

17-17: Unpacked variable streams is never used

Prefix it with an underscore or any other dummy variable pattern

(RUF059)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)
  • GitHub Check: Deploy Docs
🔇 Additional comments (5)
tests/utils/test_green_ctx.py (1)

15-23: Good error handling pattern for insufficient SMs.

The try-except block properly catches and skips tests when the device lacks sufficient SMs, which addresses the spark (sm_121) test failures mentioned in the PR objectives.

flashinfer/green_ctx.py (4)

31-31: LGTM! Required import for SM count validation.

The get_device_sm_count import is correctly added and used in both validation checks (lines 177 and 269).


173-184: Excellent early validation for SM availability.

The pre-check correctly computes the required SMs and fails fast before any CUDA operations, providing a clear error message that aligns with the test expectations.


261-261: Good optimization: constraint calculation moved outside loop.

Moving get_sm_count_constraint outside the loop avoids redundant calls, as the constraints don't change between iterations.


267-276: Proper SM validation with informative error message.

The validation correctly sums the rounded SM counts and raises a clear error if insufficient. The error message helpfully includes the actual rounded_sm_counts list to aid debugging.

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I can confirm that test_jit_example.py now passes or xfails.
test_green_ctx.py still has 7 failures:

================================================================================================================================================= short test summary info =================================================================================================================================================
FAILED tests/utils/test_green_ctx.py::test_green_ctx_creation[16-3-cuda:0] - RuntimeError: CUDA error code=914(b'CUDA_ERROR_INVALID_RESOURCE_TYPE')
FAILED tests/utils/test_green_ctx.py::test_green_ctx_kernel_execution[16-3-cuda:0] - RuntimeError: CUDA error code=914(b'CUDA_ERROR_INVALID_RESOURCE_TYPE')
FAILED tests/utils/test_green_ctx.py::test_split_device_green_ctx_by_sm_count_creation[sm_counts0-cuda:0] - RuntimeError: CUDA error code=914(b'CUDA_ERROR_INVALID_RESOURCE_TYPE')
FAILED tests/utils/test_green_ctx.py::test_split_device_green_ctx_by_sm_count_creation[sm_counts1-cuda:0] - RuntimeError: CUDA error code=914(b'CUDA_ERROR_INVALID_RESOURCE_TYPE')
FAILED tests/utils/test_green_ctx.py::test_split_device_green_ctx_by_sm_count_kernel_execution[sm_counts0-cuda:0] - RuntimeError: CUDA error code=914(b'CUDA_ERROR_INVALID_RESOURCE_TYPE')
FAILED tests/utils/test_green_ctx.py::test_split_device_green_ctx_by_sm_count_kernel_execution[sm_counts1-cuda:0] - RuntimeError: CUDA error code=914(b'CUDA_ERROR_INVALID_RESOURCE_TYPE')
FAILED tests/utils/test_green_ctx.py::test_split_device_green_ctx_by_sm_count_alignment[sm_counts1-cuda:0] - RuntimeError: CUDA error code=914(b'CUDA_ERROR_INVALID_RESOURCE_TYPE')
=================================================================================================================================== 7 failed, 10 passed, 5 skipped, 1 warning in 0.91s ====================================================================================================================================

Please see my other comment for test_sampling.py. There might be nans happening from the kernel, at least in my local env

probs_ref = torch.softmax(logits_scaled, dim=-1)

assert torch.allclose(probs, probs_ref, atol=1e-5)
assert torch.allclose(probs, probs_ref, rtol=1e-5, atol=1e-5)
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I cannot seem to repro the fix in Spark. It also seems like allclose has a default rtol=1e-5 so this may not even effectively make any change.

In fact in my local env (cu130 container), when I change the tolerance and inject print statements as

    probs_ref = torch.softmax(logits_scaled, dim=-1)
    print(f"{torch.isnan(probs).sum().item() = }")
    print(f"{torch.isnan(probs_ref).sum().item() =}")
    assert torch.allclose(probs, probs_ref, rtol=100, atol=100)

I am seeing nans.

(py312) root@c661e6d696f6:/flashinfer# pytest tests/utils/test_sampling.py -x -s
=================================================================================================================================================== test session starts ===================================================================================================================================================
platform linux -- Python 3.12.11, pytest-8.4.2, pluggy-1.6.0
rootdir: /flashinfer
configfile: pytest.ini
collected 900 items                                                                                                                                                                                                                                                                                                       

tests/utils/test_sampling.py torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
.torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
.torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
.torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
.torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
.torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
.torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
.torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
torch.isnan(probs).sum().item() = 0
torch.isnan(probs_ref).sum().item() =0
.torch.isnan(probs).sum().item() = 4873728
torch.isnan(probs_ref).sum().item() =0
F

======================================================================================================================================================== FAILURES =========================================================================================================================================================
____________________________________________________________________________________________________________________________ test_softmax[True-True-1.0-normal_distribution(std=1)-128256-989] ____________________________________________________________________________________________________________________________
...
>       assert torch.allclose(probs, probs_ref, rtol=100, atol=100)
E       AssertionError: assert False
E        +  where False = <built-in method allclose of type object at 0x16bc850>(tensor([[0.0000e+00, 7.8481e-05, 0.0000e+00,  ..., 9.0452e-06, 8.5036e-06,\n         0.0000e+00],\n        [2.4505e-05, ...05],\n        [0.0000e+00, 0.0000e+00, 7.0366e-06,  ..., 0.0000e+00, 7.1824e-06,\n         2.0367e-06]], device='cuda:0'), tensor([[0.0000e+00, 7.8481e-05, 0.0000e+00,  ..., 9.0452e-06, 8.5036e-06,\n         0.0000e+00],\n        [2.4505e-05, ...05],\n        [0.0000e+00, 0.0000e+00, 7.0366e-06,  ..., 0.0000e+00, 7.1824e-06,\n         2.0367e-06]], device='cuda:0'), rtol=100, atol=100)
E        +    where <built-in method allclose of type object at 0x16bc850> = torch.allclose

tests/utils/test_sampling.py:76: AssertionError

...

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Actionable comments posted: 1

♻️ Duplicate comments (1)
tests/utils/test_green_ctx.py (1)

24-32: Extract duplicated error handling to a helper function.

The CUDA error checking pattern is duplicated across all 5 test functions. This was previously flagged in review comments and should be addressed to improve maintainability.

Extract the error handling to a helper function:

def _skip_if_insufficient_sms(e: RuntimeError, device: str, context_msg: str):
    """Helper to skip tests when device has insufficient SMs for green context splitting."""
    if "CUDA error code=914" in str(e) or "CUDA_ERROR_INVALID_RESOURCE_TYPE" in str(e) or \
       "CUDA error code=915" in str(e) or "CUDA_ERROR_INVALID_RESOURCE_CONFIGURATION" in str(e):
        cu_dev = green_ctx.get_cudevice(torch.device(device))
        device_resource = green_ctx.get_device_resource(cu_dev)
        total_sms = device_resource.sm.smCount
        pytest.skip(f"Insufficient SMs on device. Total SMs available: {total_sms}. {context_msg}")
    raise

Then simplify each test's except block to:

    except RuntimeError as e:
        _skip_if_insufficient_sms(e, device, f"requested: num_groups={num_groups}, min_count={min_count}")

Based on learnings

Also applies to: 57-65, 94-102, 132-140, 170-178

🧹 Nitpick comments (1)
tests/utils/test_green_ctx.py (1)

15-18: Prefix unused variable with underscore.

The streams variable is unpacked but never used in this test. Prefix it with _ to indicate it's intentionally unused.

Apply this diff:

     try:
-        streams, resources = green_ctx.split_device_green_ctx(
+        _streams, resources = green_ctx.split_device_green_ctx(
             torch.device(device), num_groups, min_count
         )
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📒 Files selected for processing (2)
  • flashinfer/green_ctx.py (2 hunks)
  • tests/utils/test_green_ctx.py (5 hunks)
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flashinfer/green_ctx.py (2)
flashinfer/utils.py (2)
  • get_compute_capability (251-254)
  • round_up (589-591)
flashinfer/comm/mnnvl.py (1)
  • round_up (55-57)
tests/utils/test_green_ctx.py (2)
flashinfer/green_ctx.py (5)
  • split_device_green_ctx (126-189)
  • get_cudevice (47-53)
  • get_device_resource (56-61)
  • split_device_green_ctx_by_sm_count (192-283)
  • get_sm_count_constraint (34-44)
flashinfer/utils.py (1)
  • get_compute_capability (251-254)
🪛 GitHub Actions: pre-commit
flashinfer/green_ctx.py

[error] 1-1: pre-commit: ruff-format reformatted 2 files. Review and commit changes. Command 'pre-commit run --all-files' reported modifications by hook 'ruff-format'.

tests/utils/test_green_ctx.py

[error] 1-1: pre-commit: ruff-format reformatted 2 files. Review and commit changes. Command 'pre-commit run --all-files' reported modifications by hook 'ruff-format'.

🪛 Ruff (0.14.1)
flashinfer/green_ctx.py

177-177: Consider [*results, remaining] instead of concatenation

Replace with [*results, remaining]

(RUF005)


179-179: Consider moving this statement to an else block

(TRY300)


183-188: Avoid specifying long messages outside the exception class

(TRY003)


266-266: Avoid specifying long messages outside the exception class

(TRY003)


271-271: Consider [*results, remaining] instead of concatenation

Replace with [*results, remaining]

(RUF005)


273-273: Consider moving this statement to an else block

(TRY300)


277-282: Avoid specifying long messages outside the exception class

(TRY003)

tests/utils/test_green_ctx.py

16-16: Unpacked variable streams is never used

Prefix it with an underscore or any other dummy variable pattern

(RUF059)

🔇 Additional comments (1)
flashinfer/green_ctx.py (1)

255-283: LGTM! Consistent error handling with helpful validation.

The implementation correctly validates input SM counts and provides descriptive error messages for CUDA resource failures. The pattern is consistent with split_device_green_ctx.

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Actionable comments posted: 1

Caution

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

⚠️ Outside diff range comments (3)
flashinfer/green_ctx.py (3)

64-78: Type annotation is incorrect; results is a list.

split_resource returns a list of CUdevResource and a single remaining CUdevResource. Adjust the return type to avoid misleading type checkers.

-def split_resource(
+def split_resource(
     resource: CUdevResource,
     num_groups: int,
     min_count: int,
-) -> Tuple[CUdevResource, CUdevResource]:
+) -> Tuple[List[CUdevResource], CUdevResource]:

103-106: Parameter type should be CUdevice, not CUdevResource.

create_green_ctx_streams receives cu_dev from get_cudevice (a CUdevice) and passes it to cuGreenCtxCreate. Fix the annotation.

-def create_green_ctx_streams(
-    cu_dev: CUdevResource, resources: List[CUdevResource]
+def create_green_ctx_streams(
+    cu_dev: CUdevice, resources: List[CUdevResource]
 ) -> List[torch.Stream]:

80-101: Green-context handle leak confirmed in two functions; refactor to eliminate unnecessary context creation.

The review is correct. The codebase creates green contexts but never destroys them—no cuGreenCtxDestroy calls exist anywhere. Two functions are affected:

  1. split_resource_by_sm_count() (lines 80–100): Creates a green context solely to extract a resource already returned by split_resource(). The "refresh" operation is unnecessary; the proposed fix (use remaining directly) is valid and eliminates the leak for this function.

  2. create_green_ctx_streams() (lines 103–123): Creates green contexts in a loop to generate streams, but never stores or destroys the contexts. They go out of scope immediately after stream extraction, creating a handle leak.

The proposed fix for split_resource_by_sm_count() is sound:

-        result, remaining = split_resource(resource, 1, sm_count)
-        results.extend(result)
-        # Refresh the remaining resource for the next iteration
-        desc = checkCudaErrors(driver.cuDevResourceGenerateDesc([remaining], 1))
-        green_ctx = checkCudaErrors(
-            driver.cuGreenCtxCreate(
-                desc, cu_dev, driver.CUgreenCtxCreate_flags.CU_GREEN_CTX_DEFAULT_STREAM
-            )
-        )
-        resource = checkCudaErrors(
-            driver.cuGreenCtxGetDevResource(
-                green_ctx, driver.CUdevResourceType.CU_DEV_RESOURCE_TYPE_SM
-            )
-        )
+        result, remaining = split_resource(resource, 1, sm_count)
+        results.extend(result)
+        resource = remaining

Additionally, review create_green_ctx_streams() to determine whether green contexts must remain alive for stream validity. If yes, contexts must be retained and properly destroyed; if no, context creation can be eliminated.

♻️ Duplicate comments (1)
tests/utils/test_green_ctx.py (1)

25-38: Deduplicate skip logic via a fixture/helper.

The same RuntimeError substring checks + SM-count fetch/skip are repeated across tests. Extract once (fixture/helper) to improve maintainability and keep messages consistent. This was raised earlier; repeating here for the new blocks.

Example fixture:

# conftest.py
import pytest
import flashinfer.green_ctx as green_ctx
import torch

CUDA_RES_ERR = (
    "CUDA error code=914",
    "CUDA_ERROR_INVALID_RESOURCE_TYPE",
    "CUDA error code=915",
    "CUDA_ERROR_INVALID_RESOURCE_CONFIGURATION",
)

def skip_if_insufficient_sms(device: str, err: Exception, extra: str) -> None:
    s = str(err)
    if any(sig in s for sig in CUDA_RES_ERR):
        cu_dev = green_ctx.get_cudevice(torch.device(device))
        total_sms = green_ctx.get_device_resource(cu_dev).sm.smCount
        pytest.skip(f"Insufficient SMs ({total_sms}). {extra}")
    raise err

Then in tests:

try:
    ...
except RuntimeError as e:
    skip_if_insufficient_sms(device, e, f"requested: num_groups={num_groups}, min_count={min_count}")

Also applies to: 64-77, 107-120, 151-164, 195-208

🧹 Nitpick comments (5)
tests/utils/test_green_ctx.py (2)

57-63: Remove prints from tests; assert instead.

print(...) adds noisy logs. Prefer simple assertions on shape to keep CI output clean.

-                print(z.shape)
+                assert z.shape == (8192, 8192)
-                print(f"Partition {i}: {z.shape}")
+                assert z.shape == (4096, 4096)

Optional: consider smaller matrices (e.g., 2048 or parametrize) to reduce CI time on small GPUs.

Also applies to: 144-150


180-194: Micro: avoid repeated device construction.

Compute dev = torch.device(device) once and reuse; minor readability and overhead win.

-        _, resources = green_ctx.split_device_green_ctx_by_sm_count(
-            torch.device(device), sm_counts
-        )
+        dev = torch.device(device)
+        _, resources = green_ctx.split_device_green_ctx_by_sm_count(dev, sm_counts)
...
-            min_sm_count, sm_alignment = green_ctx.get_sm_count_constraint(
-                *green_ctx.get_compute_capability(torch.device(device))
-            )
+            min_sm_count, sm_alignment = green_ctx.get_sm_count_constraint(
+                *green_ctx.get_compute_capability(dev)
+            )
flashinfer/green_ctx.py (3)

173-193: Style and lints: list-unpack concat; try/else; centralize error checks.

  • Use list-unpack for concat (RUF005).
  • Move return to else of try (TRY300).
  • Optional: centralize error signature checks to a helper constant.
     try:
         cu_dev = get_cudevice(dev)
         resource = get_device_resource(cu_dev)
         results, remaining = split_resource(resource, num_groups, min_count)
-        resources = results + [remaining]
+        resources = [*results, remaining]
         streams = create_green_ctx_streams(cu_dev, resources)
-        return streams, resources
     except RuntimeError as e:
-        if (
-            "CUDA error code=914" in str(e)
-            or "CUDA_ERROR_INVALID_RESOURCE_TYPE" in str(e)
-            or "CUDA error code=915" in str(e)
-            or "CUDA_ERROR_INVALID_RESOURCE_CONFIGURATION" in str(e)
-        ):
+        if any(sig in str(e) for sig in (
+            "CUDA error code=914",
+            "CUDA_ERROR_INVALID_RESOURCE_TYPE",
+            "CUDA error code=915",
+            "CUDA_ERROR_INVALID_RESOURCE_CONFIGURATION",
+        )):
             raise RuntimeError(
                 f"{e}\n"
                 f"Failed to split device into {num_groups} groups with min_count={min_count}. "
                 f"This is likely due to insufficient number of SMs available on the device. "
                 f"Please reduce the number of groups or the minimum SM count per group."
             ) from e
         raise
+    else:
+        return streams, resources

259-295: Hoist constraints; empty-input check; style/lints parity with above.

  • Compute (min_sm_count, sm_alignment) once per device.
  • Validate sm_counts is non-empty (docstring promises ValueError).
  • Apply list-unpack concat and try/else.
     try:
         cu_dev = get_cudevice(dev)
         resource = get_device_resource(cu_dev)
 
-        # Round sm counts to meet the alignment and granularity requirements
-        rounded_sm_counts = []
-        for sm_count in sm_counts:
-            min_sm_count, sm_alignment = get_sm_count_constraint(
-                *get_compute_capability(dev)
-            )
-            if sm_count <= 0:
-                raise ValueError(f"SM count must be positive, got {sm_count}")
-            rounded_sm_counts.append(
-                round_up(max(sm_count, min_sm_count), sm_alignment)
-            )
+        # Round sm counts to meet the alignment and granularity requirements
+        if not sm_counts:
+            raise ValueError("sm_counts must be non-empty")
+        min_sm_count, sm_alignment = get_sm_count_constraint(
+            *get_compute_capability(dev)
+        )
+        rounded_sm_counts = []
+        for sm_count in sm_counts:
+            if sm_count <= 0:
+                raise ValueError(f"SM count must be positive, got {sm_count}")
+            rounded_sm_counts.append(round_up(max(sm_count, min_sm_count), sm_alignment))
 
         # Split the device into multiple green contexts
         results, remaining = split_resource_by_sm_count(
             cu_dev, resource, rounded_sm_counts
         )
-        resources = results + [remaining]
+        resources = [*results, remaining]
         streams = create_green_ctx_streams(cu_dev, resources)
-        return streams, resources
     except RuntimeError as e:
-        if (
-            "CUDA error code=914" in str(e)
-            or "CUDA_ERROR_INVALID_RESOURCE_TYPE" in str(e)
-            or "CUDA error code=915" in str(e)
-            or "CUDA_ERROR_INVALID_RESOURCE_CONFIGURATION" in str(e)
-        ):
+        if any(sig in str(e) for sig in (
+            "CUDA error code=914",
+            "CUDA_ERROR_INVALID_RESOURCE_TYPE",
+            "CUDA error code=915",
+            "CUDA_ERROR_INVALID_RESOURCE_CONFIGURATION",
+        )):
             raise RuntimeError(
                 f"{e}\n"
                 f"Failed to split device with SM counts {sm_counts} (rounded to {rounded_sm_counts}). "
                 f"This is likely due to insufficient number of SMs available on the device. "
                 f"Please reduce the requested SM counts or use fewer partitions."
             ) from e
         raise
+    else:
+        return streams, resources

187-193: Optional: avoid long message construction in except (TRY003).

Consider defining a small custom exception (e.g., SMAllocationError) or assembling the message inside the exception class/__str__ to satisfy linters and keep handlers catching by type, not by substrings.

Also applies to: 289-294

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 9424eef and a6ec87f.

📒 Files selected for processing (2)
  • flashinfer/green_ctx.py (2 hunks)
  • tests/utils/test_green_ctx.py (5 hunks)
🧰 Additional context used
🧬 Code graph analysis (2)
tests/utils/test_green_ctx.py (2)
flashinfer/green_ctx.py (5)
  • split_device_green_ctx (126-193)
  • get_cudevice (47-53)
  • get_device_resource (56-61)
  • split_device_green_ctx_by_sm_count (196-295)
  • get_sm_count_constraint (34-44)
flashinfer/utils.py (1)
  • get_compute_capability (251-254)
flashinfer/green_ctx.py (1)
flashinfer/utils.py (2)
  • get_compute_capability (251-254)
  • round_up (589-591)
🪛 Ruff (0.14.2)
tests/utils/test_green_ctx.py

16-16: Unpacked variable streams is never used

Prefix it with an underscore or any other dummy variable pattern

(RUF059)

flashinfer/green_ctx.py

177-177: Consider [*results, remaining] instead of concatenation

Replace with [*results, remaining]

(RUF005)


179-179: Consider moving this statement to an else block

(TRY300)


187-192: Avoid specifying long messages outside the exception class

(TRY003)


270-270: Avoid specifying long messages outside the exception class

(TRY003)


279-279: Consider [*results, remaining] instead of concatenation

Replace with [*results, remaining]

(RUF005)


281-281: Consider moving this statement to an else block

(TRY300)


289-294: Avoid specifying long messages outside the exception class

(TRY003)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)
  • GitHub Check: Deploy Docs

Comment on lines +15 to +18
try:
streams, resources = green_ctx.split_device_green_ctx(
torch.device(device), num_groups, min_count
)
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⚠️ Potential issue | 🟡 Minor

Fix unused variable per Ruff (RUF059).

streams is not used in this test. Use _ to silence the warning.

-        streams, resources = green_ctx.split_device_green_ctx(
+        _, resources = green_ctx.split_device_green_ctx(
             torch.device(device), num_groups, min_count
         )
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
try:
streams, resources = green_ctx.split_device_green_ctx(
torch.device(device), num_groups, min_count
)
try:
_, resources = green_ctx.split_device_green_ctx(
torch.device(device), num_groups, min_count
)
🧰 Tools
🪛 Ruff (0.14.2)

16-16: Unpacked variable streams is never used

Prefix it with an underscore or any other dummy variable pattern

(RUF059)

🤖 Prompt for AI Agents
In tests/utils/test_green_ctx.py around lines 15 to 18, the variable `streams`
from the tuple assignment is unused and triggers Ruff RUF059; change the
unpacking to use a throwaway name (e.g., `_, resources =
green_ctx.split_device_green_ctx(torch.device(device), num_groups, min_count)`)
so the test retains the same behavior while silencing the unused-variable
warning.

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3 participants