[AI Generated] BugFix: compute ringbuffer tolerance from PAGE_SIZE#4364
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[AI Generated] BugFix: compute ringbuffer tolerance from PAGE_SIZE#4364
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Pull request overview
This PR updates the NetworkSettings.verify_ringbuffer_settings_change test to account for netvsc ringbuffer section rounding behavior that depends on the guest PAGE_SIZE, avoiding false failures on ARM64/64KiB-page systems.
Changes:
- Compute RX/TX section-count tolerance dynamically using the guest page size (
getconf PAGE_SIZE) and per-section sizes. - Fix TX assertion bounds to use
expected_tx(instead of the priorexpected_rxtypo). - Minor comment correction (
PAGE_SIZEcasing).
The netvsc driver rounds buffer sizes up to PAGE_SIZE, causing the actual RX/TX section count to differ from the requested value. On systems with 64 KiB pages (common on ARM64), the delta can be up to ceil(65536/1728) = 38 for RX and ceil(65536/6144) = 11 for TX, which exceeds the previous hard-coded tolerance of 5. Compute the tolerance dynamically: ceil(PAGE_SIZE / section_size). Also fix a copy-paste typo in the TX assertion upper bound that incorrectly used expected_rx instead of expected_tx.
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…es throughout ring buffer verification (#4366)
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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Pull request overview
Copilot reviewed 1 out of 1 changed files in this pull request and generated 2 comments.
Comments suppressed due to low confidence (1)
lisa/microsoft/testsuites/network/networksettings.py:157
- The
2MiB adjustment used fortxbufferis a test-behavior magic number but isn't explained. Please add an inline comment (or extract a named constant) documenting why ±2 MiB is chosen and what it is intended to validate.
if original_rxbuffer - 2 > 0
else (original_rxbuffer + 2)
LiliDeng
approved these changes
Mar 22, 2026
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Summary
The netvsc driver rounds buffer sizes up to
PAGE_SIZE, causing the actual RX/TX section count to differ from the requested value. On ARM64 systems with 64 KiB pages, the delta can be up toceil(65536/1728) = 38for RX andceil(65536/6144) = 11for TX, which exceeds the previous hard-coded tolerance of ±5.This PR:
PAGE_SIZEviagetconf PAGE_SIZEceil(PAGE_SIZE / section_size)expected_rxinstead ofexpected_txValidation Results