Files
codex/.github/scripts/setup-dev-drive.ps1
Adam Perry @ OpenAI bd5c860abe ci: route build IO through Dev Drives (#31357)
## Why

Windows Cargo and Bazel jobs spend significant time in filesystem-heavy
build and cache directories. Route those directories through one CI
build root so Windows can use its Dev Drive and Unix can use a stable
cache root.

## What

- Have `setup-ci` define `CI_BUILD_ROOT`, `CARGO_TARGET_DIR`, Bazel
cache/output paths, and temp paths.
- Require Windows to find or provision a verified Dev Drive instead of
falling back to `C:`.
- Pass the shared Bazel output base to `setup-bazel` so its explicit
`output_base` does not defeat Dev Drive routing.
- Point nextest, release, and V8 source-build paths at the shared
environment contract.

## Benchmark results

One-off cold-cache WPR/ETW traces show the explicit Bazel output-base
routing removes the dominant `C:` traffic:

| sample | `C:\_bazel` | summed `C:` traffic | traced test step |
|---|---:|---:|---:|
| shard 1 before | 62.2 GiB | 85.2 GiB | 16m22s |
| shard 1 updated | 0 | 16.5 GiB | 12m05s |
| shard 3 before | 67.2 GiB | 84.6 GiB | 16m48s |
| shard 3 updated | 0 | 13.5 GiB | 11m08s |

For a cold x64 V8 source build, the retained build-tail sample showed
`D:\cargo-target` at ~1.29 GiB while measured `C:` roots totaled ~0.45
GiB (`C:\Users` ~0.33 GiB, `C:\Program Files` ~0.06 GiB, `C:\Windows`
~0.03 GiB). The full cold build took 2h20m36s.

The Bazel timing improvement is directional because both refreshed
shards failed tests. The V8 trace is a bounded build-tail sample, not
the full build. All final samples had zero lost ETW events; VHDX traffic
was excluded from the optimization ranking.

Runs: [baseline
Bazel](https://github.com/openai/codex/actions/runs/28911908527),
[updated
Bazel](https://github.com/openai/codex/actions/runs/28917133701), [V8
build tail](https://github.com/openai/codex/actions/runs/28933626678).

## Manual validation

- Ran `just fmt`.
- Ran `just test-github-scripts` (35 tests).
- Parsed GitHub Actions YAML with `yq`.
- Ran `git diff --check`.

## Stack

- [#31332](https://github.com/openai/codex/pull/31332) — parameterize
Cargo target paths
- [#31356](https://github.com/openai/codex/pull/31356) — Windows 2025
runner bump
- [#31357](https://github.com/openai/codex/pull/31357) — Dev Drive I/O
routing
2026-07-08 14:06:37 -07:00

64 lines
2.2 KiB
PowerShell

# Configure a fast drive for Windows CI jobs.
#
# GitHub-hosted Windows runners do not always expose a secondary D: volume. When
# they do not, create a Dev Drive VHD. CI depends on this path for its
# build directories where CI spends significant time doing I/O, so fail the
# job if no real Dev Drive is available.
function Test-DevDrive {
param([string]$Drive)
& fsutil devdrv query $Drive *> $null
return $LASTEXITCODE -eq 0
}
function Invoke-BestEffort {
param([scriptblock]$Script, [string]$Description)
try {
& $Script
} catch {
Write-Warning "$Description failed: $($_.Exception.Message)"
}
}
if ((Test-Path "D:\") -and (Test-DevDrive "D:")) {
Write-Output "Using existing Dev Drive at D:"
$Drive = "D:"
} else {
if (Test-Path "D:\") {
Write-Output "Existing D: volume is not a Dev Drive; provisioning a new Dev Drive VHD."
}
try {
$VhdPath = Join-Path $env:RUNNER_TEMP "codex-dev-drive.vhdx"
$SizeBytes = 64GB
if (Test-Path $VhdPath) {
Remove-Item -Path $VhdPath -Force
}
New-VHD -Path $VhdPath -SizeBytes $SizeBytes -Dynamic -ErrorAction Stop | Out-Null
$Mounted = Mount-VHD -Path $VhdPath -Passthru -ErrorAction Stop
$Disk = $Mounted | Get-Disk -ErrorAction Stop
$Disk | Initialize-Disk -PartitionStyle GPT -ErrorAction Stop
$Partition = $Disk | New-Partition -AssignDriveLetter -UseMaximumSize -ErrorAction Stop
$Volume = $Partition | Format-Volume -FileSystem ReFS -NewFileSystemLabel "CodexDevDrive" -DevDrive -Confirm:$false -Force -ErrorAction Stop
$Drive = "$($Volume.DriveLetter):"
if (-not (Test-DevDrive $Drive)) {
throw "Provisioned volume at $Drive did not pass Dev Drive verification."
}
Invoke-BestEffort { fsutil devdrv trust $Drive } "Trusting Dev Drive $Drive"
Invoke-BestEffort { fsutil devdrv enable /disallowAv } "Disabling AV filter attachment for Dev Drives"
Write-Output "Using Dev Drive at $Drive"
} catch {
throw "Failed to create Dev Drive: $($_.Exception.Message)"
}
}
"CI_BUILD_ROOT=$Drive" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append