Hi all,

Over the past few weeks, I have been systematically investigating Gerrit CI 
false negatives: workflows that failed and later passed on the same patch set 
without any code change.

During this period, several CI and HST fixes from multiple contributors were 
merged. An updated analysis performed on September 14, covering the two 
complete weeks of August 23–29 and September 7–13, found that the confirmed 
false-negative rate fell from 32/253 conclusive gerrit-verify workflows (12.6%) 
to 9/209 (4.3%), an approximately 66% reduction.

The latest figure remains provisional because some recent failures may not yet 
have received an unchanged recheck.

At signature level, the tracked QUIC, stale QEMU namespace, VCL HTTP POST and 
exact worker-barrier failures were no longer observed on patch sets containing 
the corresponding fixes.

The following patches remain open and are currently Verified +1. The occurrence 
counts are not additive, as some fixes address different stages of the same 
failure cascade:

- 46634 — preserve timeout diagnostics across retries. Diagnostic-only; no 
prevented failure claimed. Code-Review +1.
  https://gerrit.fd.io/r/c/vpp/+/46634
- 46636 — avoid repeated packet-generator barriers. CaptureTimeoutError 
appeared in 39 of the initial 65 confirmed false-negative runs, although it was 
often a secondary symptom and cannot always be attributed to this mechanism. 
Code-Review +1.
  https://gerrit.fd.io/r/c/vpp/+/46636
- 46640 — tolerate delayed BFD observations. One complete false-negative 
workflow is demonstrably covered.
  https://gerrit.fd.io/r/c/vpp/+/46640
- 46651 — keep deleted interface node names unique. The same Stats abort was 
observed in two confirmed CI occurrences.
  https://gerrit.fd.io/r/c/vpp/+/46651
- 46657 — tolerate unchanged translated NAT ports. One confirmed CI workflow 
failed on this false assertion in all three attempts. Code-Review +1.
  https://gerrit.fd.io/r/c/vpp/+/46657
- 46719 and 46720 — avoid iperf pre-exec deadlocks and make the QEMU network 
lock recoverable. Together, they address four confirmed red CI jobs involving 
89 timed-out suites.
  https://gerrit.fd.io/r/c/vpp/+/46719
  https://gerrit.fd.io/r/c/vpp/+/46720
- 46723 — wake HSI drains when ownership changes. One confirmed false-negative 
run contained the exact HSI signature addressed.
  https://gerrit.fd.io/r/c/vpp/+/46723
- 46780 — extend the BFD peer-detection window. The targeted timeout cascade 
appeared in six of seven BFD-red Maketest jobs, across five Gerrit changes.
  https://gerrit.fd.io/r/c/vpp/+/46780

Using only cases directly attributable within the initial 65-run sample, the 
pending patches cover at least five confirmed false-negative runs, or 7.7%. The 
additional Stats, NAT and newer BFD occurrences are reported separately because 
they fall outside that sample or cannot be added without double counting.

All nine pending changes are Verified +1, have no unresolved comments, and 
three already have Code-Review +1. Reviews and merges from the maintainers of 
the affected components would now be greatly appreciated.

Best regards,
Jerome
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