open-standards/.github/workflows/wai-quantum-sme.yml
Transaction Science 6517401f01 CI: the gate that decides whether a workflow runs was queued behind the work it gates
Every path-gated workflow begins with one small job -- `does this change touch
it`, or `which workspaces this change touches` for the standards build -- that
all of its real jobs declare in `needs`. All 55 of those gate jobs ran on
`linux-arm64`.

That is the one label the fleet cannot spare. Sampled while 267 runs were
queued, every waiting run had the same shape:

    [waiting]  linux-arm64    does this change touch it
    [blocked]  linux          member · dataflow device, simulated
    [blocked]  macos          member · dataflow device absent

237 runs, each holding a gate in the longest queue, and every real job blocked
behind it. Not only `linux` jobs: `macos`, `linux-hw`, `linux-arm64-hw` and
`macos-m3-ultra` jobs were blocked too. The measured effect was `linux-arm64`
263 deep against `linux` **zero**, with jetson-hub's 20 cores taking no job for
a full hour -- starved not for want of work but because the work could not be
unblocked. A gate waiting on the resource it is rationing is head-of-line
blocking, and it makes every other runner in the fleet idle on its behalf.

The gates move to `linux`. Nothing else changes: the diff is 55 `runs-on` lines
and no others, and every touched file still parses.

Why `linux` and not elsewhere. The gate is not free -- it compares
`BASE...HEAD`, which needs the merge base, so `fetch-depth: 0` is a full clone
rather than a ten-second script. `macos` is served by hosts on a Mac Studio
sitting at load 185; `linux` is a separate 20-core box that was measurably
empty. This moves a serialisation point to the least contended label; it does
not remove it, and the gate is still a single point of failure for its
workflow. The structural fix is an early-exit first step inside each job, which
costs one checkout per leg and is a larger change.

Follow-up, deliberately not bundled: jetson-hub runs at capacity 2 with 15 GB of
RAM, so 55 clones still serialise two at a time. Raising capacity helps gates
and hurts the heavy emulated-architecture jobs that share the label, so it wants
measuring on its own.

Co-Authored-By: Claude Opus 5 <[email protected]>
2026-11-03 15:19:13 -05:00

138 lines
6.6 KiB
YAML

name: wai-quantum matrix-extension member
# The fabric's matrix-extension member: the gate's fixed-point arithmetic in the
# processor's streaming vector mode (SME), 64-bit lanes, certified bit-exact
# against the CPU reference's pinned corpus digests.
#
# - sme-emulated (the container runner): the member's device tests for aarch64
# Linux, run through the host's user-mode emulator (its binfmt handler, which
# emulates SME); the runner declares the emulator, and every certificate says
# it was earned there, never on silicon.
# - sme-absent (the macOS runner, whose processor has no SME): the same build
# finds no member and says why.
#
# Silicon: a processor with SME runs the same tests with the declaration
# `cpu-matrix-sme` and no emulator.
concurrency:
group: ${{ github.workflow }}-${{ github.ref }}
cancel-in-progress: true
on:
pull_request:
paths:
- 'wai/wai-quantum/**'
- 'rust-toolchain.toml'
- '.github/workflows/wai-quantum-sme.yml'
schedule:
- cron: '14 8 * * *'
jobs:
# Does this pull request's own diff touch the paths below? This forge matches a
# workflow's `paths:` against the push, so a merge of main into a branch fires the
# workflow whatever the pull request changes; every job here waits on this answer.
# A push to main, a schedule, or anything the script cannot determine answers
# `true` (scripts/pr-touches-paths.py).
relevant:
name: does this change touch it
runs-on: linux
outputs:
run: ${{ steps.gate.outputs.run }}
steps:
- uses: actions/checkout@v5
with:
fetch-depth: 0
- id: gate
run: |
set -euo pipefail
r=$(python3 scripts/pr-touches-paths.py .github/workflows/wai-quantum-sme.yml \
"${{ github.event.pull_request.base.sha }}" \
"${{ github.event.pull_request.head.sha }}")
echo "this change touches wai-quantum-sme: $r"
echo "run=$r" >> "$GITHUB_OUTPUT"
sme-emulated:
name: member · matrix extension, emulated (aarch64 Linux)
needs: relevant
if: needs.relevant.outputs.run == 'true'
runs-on: linux
timeout-minutes: 90
container:
image: ghcr.io/cross-rs/aarch64-unknown-linux-gnu@sha256:7f8308a8734d9fcd2ebbe9a3e4bdea74af293f0799d80c3cc341e340cda49a4c
options: --memory=6g --memory-swap=6g
env:
WAI_QUANTUM_SME_EXPECT: cpu-matrix-sme
# The host's binfmt handler runs every aarch64 binary; its emulator is
# what the certificates name.
WAI_QUANTUM_SME_EMULATOR: qemu-user 8.2.2 (the host's binfmt handler)
# Run the test binary directly, so the host's handler (which emulates
# SME) runs it, not the image's older emulator.
CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_RUNNER: env
steps:
# The image has no Node for a checkout action: the forge's archive of the
# exact commit, its embedded commit id checked.
- name: Fetch the source
shell: bash
run: |
set -euo pipefail
want="${{ github.event.pull_request.head.sha || github.sha }}"
rm -rf src src.tar.gz src.tar && mkdir src
curl -sSf -o src.tar.gz "http://100.64.224.0:3400/Transaction-Science/open-standards/archive/$want.tar.gz"
gzip -dc src.tar.gz > src.tar
got="$(git get-tar-commit-id < src.tar)"
[ "$got" = "$want" ] || { echo "::error::the archive is of $got, not $want"; exit 1; }
tar -xf src.tar -C src --strip-components=1
rm src.tar.gz src.tar
- name: The member's device tests under the emulator
shell: bash
working-directory: src/wai/wai-quantum
run: |
set -euo pipefail
cache=/ci-cache/wai-quantum-sme
mkdir -p "$cache"
exec 9>"$cache/.lock"
flock 9
export RUSTUP_HOME="$cache/rustup" CARGO_HOME="$cache/cargo" CARGO_TARGET_DIR="$cache/target"
export PATH="$CARGO_HOME/bin:$PATH"
if ! command -v rustup >/dev/null; then
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --no-modify-path --profile minimal --default-toolchain none
fi
rustup toolchain install
rustup target add aarch64-unknown-linux-gnu
report="$(mktemp)"
WAI_QUANTUM_SME_REPORT="$report" cargo test --locked --release -j 6 --target aarch64-unknown-linux-gnu --features quantum_fabric_sme --test sme_member -- --test-threads=1 2>&1 | tee "$cache/device.log"
grep -qE '^test result: ok\. 9 passed; 0 failed' "$cache/device.log" || { echo "::error::not every device test ran and passed"; exit 1; }
cat "$report"
key="$WAI_QUANTUM_SME_EXPECT"
grep -qx "sme devices: as declared ($key)" "$report" || { echo "::error::the member found is not the declared one"; exit 1; }
grep -q "^sme member: key=$key .*emulator:qemu-user" "$report" || { echo "::error::the member does not say it ran under the emulator"; exit 1; }
n="$(grep -c "^sme certified: key=$key .* parity=bit-exact " "$report")"
[ "$n" = 4 ] || { echo "::error::$n of 4 certificates were earned"; exit 1; }
grep -qx "sme mutants: key=$key killed 3 of 3" "$report" || { echo "::error::a kernel mutant survived"; exit 1; }
sme-absent:
name: member · matrix extension absent (macos)
needs: relevant
if: needs.relevant.outputs.run == 'true'
# The Mac Studio's M3 Ultra has no matrix extension; the fleet's M4 Max and M5 Max
# do, and this member refuses a host that has one. It runs on the Studio by its label.
runs-on: macos-m3-ultra
timeout-minutes: 60
env:
WAI_QUANTUM_SME_EXPECT: none
steps:
- uses: actions/checkout@v5
# launchd's PATH omits cargo on the macOS host runner.
- name: Put cargo on PATH
shell: bash
run: echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
- name: No matrix extension here, and the member says so
shell: bash
working-directory: wai/wai-quantum
run: |
set -euo pipefail
[ "$(sysctl -n hw.optional.arm.FEAT_SME 2>/dev/null || echo 0)" = 0 ] || { echo "::error::this runner has SME; declare it and run the silicon tests"; exit 1; }
report="$RUNNER_TEMP/sme-report.txt"; : > "$report"
WAI_QUANTUM_SME_REPORT="$report" nice -n 10 cargo test --locked --features quantum_fabric_sme --test sme_member -- --test-threads=1 2>&1 | tee "$RUNNER_TEMP/device.log"
grep -qE '^test result: ok\. 9 passed; 0 failed' "$RUNNER_TEMP/device.log" || { echo "::error::not every device test ran and passed"; exit 1; }
grep -qx 'sme devices: as declared (none)' "$report" || { echo "::error::the absent case was not established"; exit 1; }