Tage way tunning and enlarge L3 size to 32MB

[edwu186]

tage way tunning and enlarge L3 size to 32MB

Summary by CodeRabbit

• Configuration Updates
  • L3 cache size now explicitly set to 32MB in default system configuration.
  • Branch predictor table parameters optimized with adjusted capacity allocation and associativity for improved cache performance.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: a4caa6f6-2e28-461e-9c09-6e861ac90536

📥 Commits

Reviewing files that changed from the base of the PR and between 4b6b1dc and 5c78e43.

📒 Files selected for processing (2)

• configs/example/idealkmhv3.py
• src/cpu/pred/BranchPredictor.py

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📝 Walkthrough

Walkthrough

Configuration parameters for the KMH v3 system are enhanced: L3 cache size is now explicitly set to 32MB in the ideal configuration, and BTBTAGE branch predictor table geometry is tuned by increasing table T2–T6 capacities to 8192 entries and raising table T2 associativity to 4 ways.

Changes

Cohort / File(s)	Summary
Cache Configuration configs/example/idealkmhv3.py	L3 cache size explicitly set to 32MB in default parameters.
Branch Predictor Tuning src/cpu/pred/BranchPredictor.py	BTBTAGE table geometry adjusted: tables T2–T6 increased to 8192 entries, table T2 raised to 4-way associativity.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Possibly related PRs

• Revert "cpu-o3: Refactor numWays to support per-table configuration" #795: Directly modifies BTBTAGE tableSizes and numWays parameters in the same branch predictor configuration.
• Add kmhv3 #609: Modifies both configs/example/idealkmhv3.py and src/cpu/pred/BranchPredictor.py with related configuration updates.
• cpu-o3: Refactor numWays to support per-table configuration #793: Related per-table BTBTAGE parameter tuning affecting branch predictor performance characteristics.

Suggested labels

perf, align-kmhv3

Suggested reviewers

• jensen-yan
• tastynoob

Poem

🐰 A tweak here, a tweak there,
L3 caches with such care,
TAGE tables grow so wide and deep,
Better predictions our CPU shall reap!
Performance hops along the way... 🌟

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main changes: TAGE way tuning and L3 size enlargement to 32MB are both present in the changeset.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch regression-L3-32MB

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[jensen-yan]

不要在这里修改tage 配置，应该在idealkmhv3.py 中修改，这里修改会让kmhv3.py 配置也被拉大了

[github-actions]

🚀 Coremark Smoke Test Results

Branch	IPC	Change
Base (xs-dev)	2.2665	-
This PR	2.3043	📈 +0.0378 (+1.67%)

✅ Difftest smoke test passed!