# ADR-0010: CLI Device Selection and Multi-Device Execution Semantics

## Status

Accepted

## Context

Benchmarks represent device-agnostic workloads that operate on a single device.
Users may want to run a benchmark:

- on a specific device, or
- across all devices in the system.

Device enumeration must not leak into benchmarks or runtime APIs.

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## Decision

### D1. Benchmarks are single-device by design

- A benchmark MUST define behavior for a single device only.
- A benchmark MUST accept a device identifier as input.
- Benchmarks MUST NOT enumerate or loop over multiple devices.

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### D2. CLI controls device selection

The `kernbench run` command supports an optional `--device` argument:

- If `--device <id>` is specified:
  - the benchmark executes once for the specified device.

- If `--device` is omitted:
  - the benchmark executes once using all the SIPs discovered in the topology.

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### D3. Multi-device execution is logically parallel

When running on multiple devices:

- benchmark executions are submitted to a single simulation engine instance,
- executions are logically parallel in simulation time,
- inter-device contention is naturally modeled.

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### D4. Runtime API and simulation engine remain device-scoped

- Runtime API calls operate on one device per invocation.
- The simulation engine schedules all requests deterministically.
- Neither layer enumerates devices.

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## Links

- SPEC R7, R8
- ADR-0007 (Runtime API boundaries)