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Description

Default libcudf's test harness to CUDA async allocation instead of the pool allocator, avoiding each test process's up-front reservation of 10% of device memory. Explicit allocator overrides, CTest GPU reservations, and test coverage are unchanged.

Local allocator A/B measurements on a 32 GiB V100 reduced peak device memory from approximately 29.2 GiB to 19.0 GiB (35%). Runtime measurements did not establish a clear allocator-only speedup; lower memory usage is the benefit of this change.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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Summary

Summary by CodeRabbit

• Chores
  • The default memory allocation mode is now asynchronous when no mode is specified. An explicitly configured mode continues to take precedence. This change affects the default behavior of test runs that do not set a memory allocation mode.

The testing header now documents and uses "async" as the default RMM allocation mode when GTEST_CUDF_RMM_MODE is unset. An environment-provided mode still takes precedence.

Changes: RMM default mode

Layer / File(s)	Summary
Document and set the default mode cpp/include/cudf_test/testing_main.hpp	The comment and fallback value now use "async" instead of "pool". The environment-provided mode remains unchanged.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Change: Other

Suggested reviewers: bdice, pointkernel

Merge Risk: Minimal · previous review 4a8c4

No actionable merge-blocking risk is evident in the reviewed change.

Pre-merge checks: 5

Check name	Status	Explanation
Title check		The title "Default libcudf tests to CUDA async allocation" matches the main change. The raw summary says the default RMM allocation mode for libcudf tests changed from pool to async in cpp/include/cud…
Description check		The description states that the libcudf test harness now defaults to CUDA async allocation instead of the pool allocator. It explains the reason (avoiding up-front reservation of 10% of device memory)…
Docstring Coverage		Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentat…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Title check

Explanation

The title "Default libcudf tests to CUDA async allocation" matches the main change. The raw summary says the default RMM allocation mode for libcudf tests changed from pool to async in cpp/include/cudf_test/testing_main.hpp, and an environment-provided mode still takes precedence. The title is short, specific, and states the primary change.

Full details: Description check

Explanation

The description states that the libcudf test harness now defaults to CUDA async allocation instead of the pool allocator. It explains the reason (avoiding up-front reservation of 10% of device memory), notes that explicit overrides and CTest GPU reservations are unchanged, and reports local memory measurements. This matches the raw summary's change to testing_main.hpp.

Full details: Docstring Coverage

Explanation

Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 1 functions across 1 files.

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Recent review info

Run configuration

• Source mode: Auto
• Repository: NVIDIA/cudf
• Branch: main
• File: .coderabbit.yaml
• Commit: 4abb25f
• Layers: Repository YAML
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• Run ID: 8d8a71d4-1d67-4e0a-8450-6fa86d7b4a84

Commits

Reviewing files that changed from the base of the PR and between 4abb25f and 4a8c4c7.

Files selected for processing: 1

• cpp/include/cudf_test/testing_main.hpp

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