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nvfp4-megamoe-kernel/dsv4/ops/router.py

94 lines
2.7 KiB
Python

"""torch.library.custom_op wrappers and dispatch for the Router kernels.
Mirrors the pattern in dsv4/ops/custom_ops.py:
- Routers are registered into an integer-keyed table.
- The custom_op takes the integer ID and tensor args only.
- Dynamo can't trace through the kernel; the op is opaque.
"""
import torch
from dsv4.kernels.router import (
dense_router_dispatch, # picks decode vs prefill internally
hash_router_dispatch,
)
_next_router_id = 0
_router_registry: dict[int, object] = {}
def register_router(router) -> int:
global _next_router_id
rid = _next_router_id
_next_router_id += 1
_router_registry[rid] = router
return rid
def get_router(rid: int):
return _router_registry[rid]
def warmup_router_compilation(router) -> None:
"""Trigger eager JIT compilation for the router's kernel path.
Runs a dummy forward at max_num_tokens to compile the kernel for the
expected shape range. Caller already has the buffers allocated.
"""
if router.mode == "dense":
# Dummy forward at small N triggers decode-path compile.
# CuTeDSL fused kernel is WIP — falls through to prefill path.
dummy = torch.zeros(
1, router.hidden_size,
dtype=torch.bfloat16, device=router.device,
)
try:
router._run_dense_impl(dummy)
except Exception:
pass # CuTeDSL kernel not yet working; prefill path is fine
else:
dummy = torch.zeros(1, dtype=torch.int32, device=router.device)
router._run_hash_impl(dummy)
# ----- Dense router custom op -----
@torch.library.custom_op("dsv4::dense_router", mutates_args=())
def dense_router_op(
hidden_states: torch.Tensor,
router_id: int,
num_experts: int,
top_k: int,
) -> tuple[torch.Tensor, torch.Tensor]:
router = get_router(router_id)
return router._run_dense_impl(hidden_states)
@dense_router_op.register_fake
def _(hidden_states, router_id, num_experts, top_k):
N = hidden_states.shape[0]
device = hidden_states.device
return (
torch.empty(N, top_k, dtype=torch.float32, device=device),
torch.empty(N, top_k, dtype=torch.int32, device=device),
)
# ----- Hash router custom op -----
@torch.library.custom_op("dsv4::hash_router", mutates_args=())
def hash_router_op(
token_ids: torch.Tensor,
router_id: int,
top_k: int,
) -> tuple[torch.Tensor, torch.Tensor]:
router = get_router(router_id)
return router._run_hash_impl(token_ids)
@hash_router_op.register_fake
def _(token_ids, router_id, top_k):
N = token_ids.shape[0]
device = token_ids.device
return (
torch.empty(N, top_k, dtype=torch.float32, device=device),
torch.empty(N, top_k, dtype=torch.int32, device=device),
)