Run one x64 job on pull requests; main runs the rest by ejc3 · Pull Request #923 · ejc3/fcvm

ejc3 · 2026-09-13T15:33:32Z

Why

Every PR push launched four x64 metal runners: Host-x64, both Host-Root-x64 modes and Container-x64. c5d.metal is the largest runner line item (about $925 of roughly $2,000 in runner spend since 2026-07-22). Three of those four jobs run paths the arm64 jobs already cover on the same PR.

What changes

skip-check now plans the self-hosted matrix.
- pull_request: every arm64 job, plus Host-Root-x64-SnapshotEnabled. That job takes the privileged suite through a snapshot miss and a restore on x86, which is where the arch-specific KVM and vCPU state code lives.
- push to main: every job that has not already succeeded on a PR run of the same tree. After a normal merge that means the other three x64 jobs, so x86 still gets the full matrix before release. If the PR run skipped the matrix (docs-only), main skips it too, as before.
- Any other event: the full matrix. That covers workflow_dispatch (and so ci-train), the Build Kernels workflow_run, and a push whose tree never passed on a PR.
host, host-root and container take their matrix from the plan via fromJSON, and skip when their list is empty.

Tests

New tests in tests/test_ci_workflow_coverage.rs run the real planner step with fake gh and git. They check:
- A PR gets exactly one x64 job and every arm64 job.
- The PR run and the main run together cover the full matrix, with no job running twice.
- A push with no passing PR run of the same tree gets the full matrix.
- After a full or matrix-skipped PR run, main runs nothing.
- Each self-hosted job reads its matrix from the plan.
Results: 28/28 pass, and cargo fmt --check, clippy and actionlint are clean.
This PR's own CI run is the live check: it should show four arm64 jobs and one x64 job.

Summary by CodeRabbit

CI Improvements
- Pull request validation now runs a focused test matrix while maintaining coverage across supported environments.
- Main-branch builds run only the remaining checks when pull request coverage is available, reducing unnecessary duplicate work.
- Builds run the complete matrix when prior pull request coverage is unavailable or incomplete.
- Manual and workflow-triggered runs continue to validate the full matrix.
Tests
- Added coverage to verify matrix planning and execution behavior across supported event types.

chatgpt-codex-connector · 2026-09-13T15:33:35Z

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coderabbitai · 2026-09-13T15:33:41Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 7bcd13ad-9fab-4703-8a57-4a0ef759bf62

📥 Commits

Reviewing files that changed from the base of the PR and between 92ced2a and 28581a8.

📒 Files selected for processing (2)

.github/workflows/ci.yml
tests/test_ci_workflow_coverage.rs

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

📝 Walkthrough

Walkthrough

Changes

CI Matrix Planning

Layer / File(s)	Summary
Matrix planner `.github/workflows/ci.yml`	`skip-check` now plans self-hosted matrices for pull requests, pushes, and other events. It emits family-specific matrices, run flags, and `skip`.
Planned matrix consumption `.github/workflows/ci.yml`	The `host`, `host-root`, and `container` jobs now use planner outputs for their matrices and execution conditions. The skipped notice text was updated.
Planner validation `tests/test_ci_workflow_coverage.rs`	Tests execute the planner with simulated GitHub data and validate pull request coverage, push completion, fallback events, skipped matrices, and job wiring.

Priority: ⬇️ Low

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Other

Sequence Diagram(s)

sequenceDiagram
  participant GitHubEvent
  participant skip_check
  participant GitHubAPI
  participant SelfHostedJobs
  GitHubEvent->>skip_check: provide event type and tree
  skip_check->>GitHubAPI: query matching PR runs
  GitHubAPI-->>skip_check: return completed job names
  skip_check->>SelfHostedJobs: emit family matrices and run flags
  SelfHostedJobs-->>GitHubEvent: execute planned jobs

Merge Risk: ⚪ Minimal · up to 28581

The CI planner preserves the intended PR-plus-main coverage and correctly skips empty job families. No actionable merge risk remains.

🚥 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 summarizes the primary CI matrix change: pull requests run one x64 job, and main runs the remaining jobs.
Docstring Coverage	✅ Passed	Docstring coverage is 80.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 1 files. (1 skipped: 1 …
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 💡 1

🛠️ Fix failing CI checks 💡

Create stacked PR
Commit on current branch

📝 Generate docstrings

Create stacked PR
Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch ci/pr-single-x64

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ejc3 · 2026-09-13T15:46:19Z

@coderabbitai review

coderabbitai · 2026-09-13T15:46:24Z

⚠️ Action not completed

Review rate limited.

Note: CodeRabbit is an incremental review system and does not re-review already reviewed commits. This command is applicable only when automatic reviews are paused.

skip-check now plans the self-hosted matrix. A pull request gets every arm64 job plus Host-Root-x64-SnapshotEnabled; a push to main runs every job that has not already passed on a PR run of the same tree; other events run the full matrix. host, host-root and container read their matrix from the plan, and the coverage tests run the planner with fake gh and git.

ejc3 · 2026-09-13T23:11:17Z

@coderabbitai review

coderabbitai · 2026-09-13T23:11:24Z

⚠️ Action not completed

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Note: CodeRabbit is an incremental review system and does not re-review already reviewed commits. This command is applicable only when automatic reviews are paused.

ejc3 · 2026-09-13T23:19:18Z

@coderabbitai review

coderabbitai · 2026-09-13T23:19:27Z

✅ Action performed

Review finished.

Note: CodeRabbit is an incremental review system and does not re-review already reviewed commits. This command is applicable only when automatic reviews are paused.

ejc3

NOT-A-DEFECT: CodeRabbit's walkthrough for 28581a8 reports no actionable comments, minimal merge risk and 5 of 5 pre-merge checks passed; it carries no finding. Its one suggestion, "Fix failing CI checks", referred to Host-Root-x64-SnapshotEnabled in run 34783983989 attempt 1, whose runner (i-0cc85225bb0c40d3d, r5d.metal spot) was reclaimed by EC2 (Server.SpotInstanceTermination) mid test-root. The rerun in attempt 2 passed, and every check on this head is green.

ejc3 mentioned this pull request Sep 13, 2026

Record disk I/O for each self-hosted CI job #924

Merged

ejc3 force-pushed the ci/pr-single-x64 branch from c873f10 to 28581a8 Compare September 13, 2026 21:29

ejc3 commented Sep 14, 2026

View reviewed changes

ejc3 merged commit 750b5ae into main Sep 14, 2026
25 of 27 checks passed

ejc3 deleted the ci/pr-single-x64 branch September 14, 2026 00:22

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Run one x64 job on pull requests; main runs the rest - #923

Run one x64 job on pull requests; main runs the rest#923
ejc3 merged 1 commit into
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