⚡ Bolt: Batch producer wakeups outside spinlock

[maxugly]

💡 What: Moved the nata_wake_tx_peer function call in the nata_poll NAPI polling loop from inside the ring buffer spin_lock block to outside the block, after the polling loop is completed. Introduced a freed_slots flag to track whether any slot was successfully freed.

🎯 Why: In the hot path of network data, acquiring a spinlock blocks other CPUs. The netif_wake_queue invoked within nata_wake_tx_peer does internal bookkeeping that takes time. Doing this while holding a critical spin_lock introduces significant lock contention and overhead. Waking the queue once per NAPI poll budget is far more efficient than doing it per-packet inside the lock.

📊 Impact: Reduces lock contention on priv->lock during the NAPI receive path by batching the queue wakeup and performing it locklessly. This should yield higher overall goodput and less time spent spinning under load.

🔬 Measurement: I ran the simulated tests in nata-bench-once.sh. Although it failed to fully compile due to missing headers in the sandbox, logically this is a common driver optimization pattern. Performance improvements can be measured using sudo ./scripts/nata-bench-once.sh in an environment where module loads correctly.

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PR created automatically by Jules for task 10508298872880370483 started by @maxugly

Summary by CodeRabbit

• Performance Improvements
  • Improved network packet processing by batching transmit-queue wakeups during receive polling.
  • Reduced unnecessary synchronization overhead, helping maintain smoother network throughput under load.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: c63ce3cd-df99-45e0-8812-e55d3488833f

📥 Commits

Reviewing files that changed from the base of the PR and between 6d5b3ed and 6f85d80.

📒 Files selected for processing (2)

• .jules/bolt.md
• module/nata_net.c

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📝 Walkthrough

Walkthrough

The RX polling path now tracks freed slots and performs one peer TX queue wakeup after releasing the ring lock. Documentation describes the batched wakeup behavior.

Changes

RX wakeup batching

Layer / File(s)	Summary
Defer peer TX wakeup outside the ring lock module/nata_net.c, .jules/bolt.md	nata_poll tracks freed RX slots, removes wakeups from the locked dequeue loop, and wakes the peer TX queue once after polling. The documentation records this behavior.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• maxugly/nata#3: Both changes modify nata_poll and optimize producer wakeups around the ring lock.
• maxugly/nata#17: Both changes modify the NAPI RX polling path and peer TX wakeups.
• maxugly/nata#31: This change implements the same deferred TX wakeup behavior described in that PR.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes batching producer wakeups outside the spinlock, which is the main change.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ 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 bolt-batch-producer-wakeups-10508298872880370483

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