| 1 | # SPDX-License-Identifier: Apache-2.0 |
| 2 | # SPDX-FileCopyrightText: Copyright contributors to the vLLM project |
| 3 | """Launch-config selection for the ReplaySSM Mamba2 output_only decode kernel. |
| 4 | |
| 5 | Mirrors ``mamba_ssm.py``: a hard-coded heuristic per kernel, plus an |
| 6 | ``override`` context manager for benchmarks/tests/config sweeps. Hardware is |
| 7 | auto-detected (Blackwell vs not) so call sites need not thread it through. |
| 8 | """ |
| 9 | |
| 10 | import functools |
| 11 | |
| 12 | from vllm.platforms import current_platform |
| 13 | from vllm.triton_utils import triton |
| 14 | |
| 15 | |
| 16 | @functools.cache |
| 17 | def _is_blackwell() -> bool: |
| 18 | try: |
| 19 | return current_platform.is_device_capability_family(100) |
| 20 | except Exception: |
| 21 | return False |
| 22 | |
| 23 | |
| 24 | # Per-kernel overrides keyed by the kernel name passed to get_replayssm_config. |
| 25 | _overrides: dict[str, tuple] = {} |
| 26 | |
| 27 | |
| 28 | def _dstate_tile(dstate: int, tile: int) -> int: |
| 29 | return max(16, min(tile, triton.next_power_of_2(dstate))) |
| 30 | |
| 31 | |
| 32 | def _mamba2_output_only(dstate, L, is_blackwell): |
| 33 | # (block_size_m, num_warps, nf_dstate_tile, fl_dstate_tile, num_stages); |
| 34 | # decoupled dstate tiling, serving-batch optimum, dtype-independent per device. |
| 35 | if is_blackwell: |
| 36 | return 64, 1, _dstate_tile(dstate, 32), _dstate_tile(dstate, 64), 2 |
| 37 | return 16, 1, _dstate_tile(dstate, 64), _dstate_tile(dstate, 128), 2 |
| 38 | |
| 39 | |
| 40 | def get_replayssm_config(kernel: str, **shape) -> tuple: |
| 41 | """Return the launch config for ``kernel`` (override > tuned default). |
| 42 | |
| 43 | kernel: "mamba2_output_only". ``shape`` carries the keying dims (dstate; |
| 44 | ``L`` for the buffer length, default 16); hardware is auto-detected. |
| 45 | """ |
| 46 | if kernel in _overrides: |
| 47 | return _overrides[kernel] |
| 48 | bw = _is_blackwell() |
| 49 | if kernel == "mamba2_output_only": |
| 50 | return _mamba2_output_only(shape["dstate"], shape.get("L", 16), bw) |
| 51 | raise ValueError(f"unknown ReplaySSM kernel config key: {kernel}") |