Fix windows again

[illuzen]

Overview

Fixes GPU device selection and stability issues on Windows systems with both discrete and integrated GPUs.

What changed

GPU Adapter Selection (engine-gpu)

• Skip integrated GPUs when discrete GPUs are available - Prevents resource contention and driver instability from mining on both simultaneously (root cause of device loss crashes)
• Added --allow-integrated flag - Opt-in to use integrated GPUs alongside discrete GPUs if desired
• Added DEVICE_LOST thread-local flag - Marks GPU workers as permanently dead after device loss to prevent "Buffer is already mapped" panics on retry
• Clear corrupted resources on device loss - Drops buffer state when device fails

Async Runtime (engine-gpu)

• Replaced futures::executor::block_on with tokio - Proper async timeout support for GPU initialization
• Added 30-second timeout on request_device() - Prevents infinite hangs if driver is unresponsive
• Handle nested runtime correctly - Uses block_in_place when called from within existing tokio runtime

GPU Tier Detection (engine-gpu)

• Fixed Qualcomm Adreno regex - "Adreno 627" now correctly matches 600 series, not 700 series
• Merged duplicate AMD RDNA 1 patterns - Consolidated \b5[56]00\b and rx 5\d{3} into single tier
• Replaced once_cell with std::sync::LazyLock - Reduced dependency surface (requires Rust 1.80+)

CLI (miner-cli)

• Added --allow-integrated / MINER_ALLOW_INTEGRATED - Available on both serve and benchmark commands
• Added 🎯 emoji to solution found logs - Easier to spot in log output

Validation

• cargo test -p engine-gpu - 14 tests pass including:
  • windows_amd_discrete_plus_apu_uses_only_discrete - Exact repro of the failing scenario
  • allow_integrated_flag_keeps_both_gpu_types - Verifies opt-in works
• cargo clippy --workspace --all-targets -- -D warnings - Clean
• cargo build --workspace - Builds successfully
• Manual benchmark test passes on macOS

Test Scenario

The failing Windows system had:

• GPU 0: Radeon RX 560X (DiscreteGpu, Vulkan)
• GPU 1: AMD Radeon Vega 8 (IntegratedGpu, Vulkan)

Before: Both GPUs initialized and used → Vega 8 hit device loss → "Buffer is already mapped" panic

After:

• Default: Only RX 560X used, Vega 8 skipped with log message
• With --allow-integrated: Both used (at user's risk)

Risks and Mitigations

Risk	Mitigation
Users may want to use integrated GPU	--allow-integrated flag provides opt-in
Device loss could still occur on discrete GPU	DEVICE_LOST flag prevents panic on retry
Timeout may be too short/long for some drivers	30s is conservative; can be made configurable later

Follow-ups

• Consider making init timeout configurable (--gpu-init-timeout)
• Monitor if any users report issues with the new default behavior

---

Note

Medium Risk
Changes which GPUs are selected by default (behavioral change for iGPU+dGPU rigs). Device-loss handling alters worker lifecycle but reduces crash risk on failed GPUs.

Overview
Improves Windows hybrid-GPU stability by changing default adapter selection: when a discrete GPU is present, integrated/APU adapters are no longer used unless the user opts in. select_adapters gains an allow_integrated flag, and GpuEngine::try_new / resolve_gpu_configuration thread that through init.

--allow-integrated (and MINER_ALLOW_INTEGRATED) is added on serve and benchmark, wired via ServiceConfig into GPU engine setup. Benchmarks, examples, and tests call try_new(..., false) by default.

After device loss, a per-worker DEVICE_LOST flag makes further searches return Cancelled immediately, and thread-local GPU buffers are cleared to avoid retry panics (e.g. “buffer already mapped”). Adapter-selection unit tests are updated for the new default (single discrete on best backend) and expanded for RX 560X + Vega 8 and the opt-in path.

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Cursor Bugbot has reviewed your changes using default effort and found 2 potential issues.

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[cursor]

Dead GPU worker spins forever

High Severity

After device loss, DEVICE_LOST makes search_range return EngineStatus::Cancelled with zero hashes, but miner-service GPU workers treat Cancelled like a normal job change and keep taking work. The thread never exits, so that GPU worker contributes 0 H/s indefinitely while still consuming jobs.

Additional Locations (1)

• crates/engine-gpu/src/lib.rs#L610-L625

 

^{Triggered by learned rule: Fail-early on persistent GPU device loss}

^{Reviewed by Cursor Bugbot for commit 6324c19. Configure here.}

[cursor]

Integrated GPU skipped when discrete init fails

Medium Severity

When a discrete GPU is enumerated, integrated adapters are removed from select_adapters before initialization. If the discrete request_device times out or errors and is skipped, init never tries the integrated GPU, so try_new can fail with no usable GPU even though a working integrated adapter was available.

Additional Locations (1)

• crates/engine-gpu/src/lib.rs#L324-L334

 

^{Reviewed by Cursor Bugbot for commit 6324c19. Configure here.}

[n13]

Verdict: Request changes (close — two correctness gaps)

Solid, well-tested fix for the iGPU+dGPU device-loss crash on Windows, and preferring discrete GPUs by default is reasonable. Requesting changes for two issues (both flagged by Bugbot and independently confirmed below), plus a scope/description mismatch.

What this PR actually changes (diff vs main)

• Threads allow_integrated through CLI -> ServiceConfig -> resolve_gpu_configuration -> GpuEngine::try_new -> select_adapters.
• select_adapters drops IntegratedGpu when any DiscreteGpu is present (unless allow_integrated).
• DEVICE_LOST thread-local: after BatchResult::DeviceLost, mark the worker dead, clear WORKER_RESOURCES, and short-circuit search_range to Cancelled { 0 }.
• Test updates + new tests.

Heads up: the description also lists "Async Runtime" (tokio/block_in_place/30s timeout), "GPU Tier Detection" (Adreno/RDNA regex, once_cell -> LazyLock), and the solution emoji. None of those are in this diff — they're already on main (gpu_tiers.rs already uses std::sync::LazyLock, Cargo.toml already has tokio time + futures, miner-service already logs the emoji). Please trim the description to what this PR actually changes.

1) Dead GPU worker becomes a silent no-op (High) — engine-gpu/src/lib.rs + miner-service/src/lib.rs

After device loss, search_range returns Cancelled { hash_count: 0 } on every subsequent call. In worker_loop, Cancelled is treated as a normal "new block" (info log), so the worker blocks on job_rx.recv(), wakes on each job, returns 0, and sleeps again — indefinitely. Not a busy-spin, but the thread never exits and contributes 0 H/s permanently. Nothing downstream notices: handle_connection only sums hash_count and there is no all-workers-dead health check, so a single-GPU rig silently mines at 0 H/s while still looking "alive".

This conflicts with the repo's fail-early rule ("never have a silent failure; all failures must produce error logging"). It is also an observability regression vs. the prior behavior, where the worker thread died on the panic and made start_job's try_send fail loudly every block. Now it is one error log, then silence.

Suggestion: keep surfacing the lost device (error log each time a job is handed to a lost worker), and for the single-GPU / all-GPU-workers-lost case, exit the process so a supervisor (systemd/docker) restarts it instead of running idle.

2) Integrated GPU excluded before init, so discrete-init failure leaves no GPU (Medium) — engine-gpu/src/lib.rs

select_adapters removes integrated adapters whenever a discrete adapter is enumerated, before init runs. In init, if the discrete request_device times out (the 30s path) or errors, that adapter is continue-skipped; if it was the only selected adapter, contexts.is_empty() and try_new fails with "No GPU adapters could be initialized" — even though a working integrated GPU was present. That is exactly the flaky-Windows-driver case this PR targets.

Suggestion: only exclude integrated adapters after at least one discrete device initializes successfully (or fall back to integrated if none do).

Minor

• Default behavior change: iGPU+dGPU users lose the iGPU unless they pass --allow-integrated. Documented and reasonable — just calling it out.
• Resource clearing on device loss looks correct: the DeviceLost paths in run_single_batch never unmap (buffer was not mapped), so dropping WORKER_RESOURCES avoids the double-map / "buffer already mapped" panic. Good.

What's good

• Clean parameter threading and config wiring.
• Excellent test coverage, including the exact RX 560X + Vega 8 repro and the --allow-integrated opt-in path.
• The device-loss fix genuinely removes the panic.

Happy to approve once (1) is addressed (it is the one that violates fail-early); (2) is worth fixing in the same pass since it serves the same Windows-stability goal.

[n13]

Verdict: Approve

Both issues from the previous review are properly fixed. Verified locally on 90a274ba: cargo clippy --workspace --all-targets -- -D warnings is clean, and the 7 adapter_selection_tests pass.

Issue 1 (dead GPU worker silent no-op) — resolved

The new EngineStatus::DeviceLost variant cleanly separates device loss from normal cancellation. search_range now returns DeviceLost, and worker_loop logs an error and breaks out of the loop so the worker thread exits permanently (then runs the existing GPU resource cleanup). run_benchmark also breaks on DeviceLost. This satisfies fail-early — the failure is loud and the dead worker stops consuming jobs. All exhaustive match sites were updated for the new variant; the only un-updated EngineStatus match (engine-cpu test, line 242) uses a wildcard arm, so it still compiles.

Issue 2 (integrated excluded before init) — resolved

select_adapters no longer filters integrated GPUs; it returns all non-CPU adapters on the best backend (discrete first). The integrated-vs-discrete decision now happens in init() after initialization, based on what actually succeeded: integrated GPUs are dropped only if at least one discrete GPU initialized (unless --allow-integrated). A discrete-init failure now correctly falls back to a working integrated GPU. Logic confirmed by the updated select_adapters tests.

Minor follow-ups (non-blocking)

• The post-init filtering in init() isn't unit-tested (it lives in the async hardware path). Consider extracting it into a small pure helper (input: device types that initialized; output: which to keep) so both "discrete present -> drop integrated" and "discrete failed -> keep integrated" get direct coverage.
• After a GPU worker exits, WorkerPool::start_job keeps try_send-ing to the now-disconnected channel each block and logs "Failed to send job ... Channel full - worker may be stuck". It is loud (good) but the message is misleading for a dead/disconnected worker, and metrics::set_gpu_devices stays at the original count. For a GPU-only rig the process keeps running idle after the worker exits; a future enhancement could detect "all workers dead" and exit so a supervisor restarts it.
• The PR description still lists changes not in this diff (Async Runtime / block_in_place, GPU Tier Detection, once_cell -> LazyLock) — those are already on main. Worth trimming so the changelog matches the diff, but not blocking.

Nice work — DeviceLost and post-init filtering are the right shapes for both fixes.