kvcache-ai-ktransformers/kt-kernel/python/sft/base.py
mrhaoxx f36699affd feat(sft): AMX MoE SFT backend with LoRA support
Complete SFT (Supervised Fine-Tuning) backend for MoE models using AMX SIMD:

Core C++ implementation:
- sft_moe.hpp: Forward/backward with LoRA fused operations (~5500 lines)
- moe-sft-tp.hpp: Tensor-parallel wrapper for multi-NUMA
- amx/moe-sft-tp.hpp: AMX-specific TP implementation
- avx_kernels.hpp: AVX512 SIMD kernels for LoRA GEMM
- amx_kernels.hpp: AMX tile kernels for Panel5 rank-outer optimization
- worker_pool: RDTSC profiling, Chrome trace output, SFT timer infrastructure
- ext_bindings.cpp: SFT MOE pybind bindings (BF16/INT8/INT4 + SkipLoRA variants)

Python sft/ submodule (kt_kernel.sft):
- base.py: BaseSFTMoEWrapper with buffer management (template method pattern)
- amx.py: AMXSFTMoEWrapper (weight loading, C++ task construction)
- autograd.py: KTMoEFunction (torch.autograd.Function for distributed training)
- layer.py: KTMoELayerWrapper (nn.Module replacing HF MoE layers)
- arch.py: MOEArchConfig (Qwen3/DeepSeek/Mixtral architecture detection)
- weights.py: Expert weight extraction and checkpoint loading
- lora.py: PEFT LoRA adaptation (view buffers, grad buffers, save/load adapter)
- wrapper.py: wrap_moe_layers_with_kt_wrapper, load_kt_model, build_kt_device_map
- config.py: KTConfig dataclass (DeepSpeed-style opaque config passthrough)
- dist_utils.py: Distributed gather/scatter, checkpoint-phase detection

Design decisions:
- Rank-0-only expert pattern: only rank 0 holds C++ wrapper and expert weights
- DeepSpeed-style integration: accelerate keeps only KTransformersPlugin (framework
  interaction fields), all logic in kt_kernel.sft
- Inference isolation: importing kt_kernel does not load sft/ submodule
- Old field name compatibility: _get_kt_config() converts kt_xxx→xxx automatically

Verified: Qwen3-235B-A22B 4GPU AMXBF16 training, loss converges normally.
2026-04-08 23:11:00 +08:00

402 lines
15 KiB
Python

# Base classes for SFT MoE operations
# SPDX-License-Identifier: Apache-2.0
"""
SFT (Supervised Fine-Tuning) MoE base classes and buffer management.
Provides:
- KExpertsSFTBuffer: Grow-only shared buffer for forward/backward passes
- BaseSFTMoEWrapper: Abstract base with concrete buffer management (template method pattern)
"""
from __future__ import annotations
import torch
from typing import Optional, Tuple
from abc import ABC, abstractmethod
from ..experts_base import _MoEBase
class KExpertsSFTBuffer:
"""
CPU buffer management for SFT expert computation.
Single grow-only buffer (never shrinks). Callers must use [:qlen] slicing
since the buffer may be larger than the current batch.
"""
_shared_buffer: Optional["KExpertsSFTBuffer"] = None
def __init__(
self,
qlen: int,
hidden_size: int,
moe_intermediate_size: int,
num_experts: int,
num_experts_per_tok: int,
lora_rank: int,
dtype: torch.dtype = torch.bfloat16,
):
self.qlen = qlen
self.hidden_size = hidden_size
self.moe_intermediate_size = moe_intermediate_size
self.num_experts = num_experts
self.num_experts_per_tok = num_experts_per_tok
self.lora_rank = lora_rank
self.dtype = dtype
pin_memory = False
# Forward buffers
self.input_cpu = torch.empty((qlen, hidden_size), dtype=dtype, device="cpu", pin_memory=pin_memory)
self.expert_ids_cpu = torch.empty(
(qlen, num_experts_per_tok), dtype=torch.int64, device="cpu", pin_memory=pin_memory
)
self.weights_cpu = torch.empty(
(qlen, num_experts_per_tok), dtype=torch.float32, device="cpu", pin_memory=pin_memory
)
self.output_cpu = torch.empty((qlen, hidden_size), dtype=dtype, device="cpu", pin_memory=pin_memory)
# Backward buffers
self.grad_output_cpu = torch.empty((qlen, hidden_size), dtype=dtype, device="cpu", pin_memory=pin_memory)
self.grad_input_cpu = torch.empty((qlen, hidden_size), dtype=dtype, device="cpu", pin_memory=pin_memory)
self.grad_weights = torch.empty((qlen, num_experts_per_tok), dtype=torch.float32, device="cpu")
# Batch size tensor for C++ interface
self.bsz_tensor = torch.tensor([qlen], dtype=torch.int32, device="cpu")
@classmethod
def get_buffer(
cls,
qlen: int,
hidden_size: int,
moe_intermediate_size: int,
num_experts: int,
num_experts_per_tok: int,
lora_rank: int,
dtype: torch.dtype = torch.bfloat16,
) -> "KExpertsSFTBuffer":
"""Get or grow the single shared buffer. Only reallocates when qlen exceeds capacity."""
buf = cls._shared_buffer
if buf is not None and qlen <= buf.qlen:
return buf
cls._shared_buffer = cls(
qlen=qlen,
hidden_size=hidden_size,
moe_intermediate_size=moe_intermediate_size,
num_experts=num_experts,
num_experts_per_tok=num_experts_per_tok,
lora_rank=lora_rank,
dtype=dtype,
)
return cls._shared_buffer
@classmethod
def clear_cache(cls) -> None:
"""Clear the shared buffer."""
cls._shared_buffer = None
class BaseSFTMoEWrapper(_MoEBase, ABC):
"""
Base class for SFT MoE CPU operations with concrete buffer management.
Subclasses implement:
- _make_forward_task(buffer, save_for_backward) -> C++ task object
- _make_backward_task(buffer) -> C++ task object
- load_weights(physical_to_logical_map_cpu)
- init_lora_weights(...)
- update_lora_weights()
"""
def __init__(
self,
layer_idx: int,
num_experts: int,
num_experts_per_tok: int,
hidden_size: int,
moe_intermediate_size: int,
num_gpu_experts: int,
cpuinfer_threads: int,
threadpool_count: int,
weight_path: str,
chunked_prefill_size: int,
lora_rank: int = 16,
lora_alpha: float = 32.0,
max_cache_depth: int = 1,
):
self.cpu_infer = self._get_cpu_infer(cpuinfer_threads, threadpool_count)
self._validate_base_config(
num_experts=num_experts,
hidden_size=hidden_size,
moe_intermediate_size=moe_intermediate_size,
num_experts_per_tok=num_experts_per_tok,
)
self._validate_sft_config(lora_rank, lora_alpha, max_cache_depth)
self.layer_idx = layer_idx
self.num_experts = num_experts
self.num_experts_per_tok = num_experts_per_tok
self.hidden_size = hidden_size
self.moe_intermediate_size = moe_intermediate_size
self.num_gpu_experts = num_gpu_experts
self.weight_path = weight_path
self.chunked_prefill_size = chunked_prefill_size
self.threadpool_count = threadpool_count
self.lora_rank = lora_rank
self.lora_alpha = lora_alpha
self.lora_scaling = lora_alpha / lora_rank
self.max_cache_depth = max_cache_depth
self.gate_lora_a: Optional[torch.Tensor] = None
self.gate_lora_b: Optional[torch.Tensor] = None
self.up_lora_a: Optional[torch.Tensor] = None
self.up_lora_b: Optional[torch.Tensor] = None
self.down_lora_a: Optional[torch.Tensor] = None
self.down_lora_b: Optional[torch.Tensor] = None
self._weights_loaded: bool = False
self._lora_initialized: bool = False
self._cache_depth: int = 0
self._is_skip_lora: bool = False
self.moe = None
@staticmethod
def _validate_sft_config(lora_rank: int, lora_alpha: float, max_cache_depth: int) -> None:
if lora_rank <= 0:
raise ValueError(f"lora_rank must be positive, got {lora_rank}")
if lora_alpha <= 0:
raise ValueError(f"lora_alpha must be positive, got {lora_alpha}")
if max_cache_depth <= 0:
raise ValueError(f"max_cache_depth must be positive, got {max_cache_depth}")
# ========== Abstract methods for subclasses ==========
@abstractmethod
def _make_forward_task(self, buffer: KExpertsSFTBuffer, save_for_backward: bool):
"""Construct the C++ forward task object. Backend-specific."""
...
@abstractmethod
def _make_backward_task(self, buffer: KExpertsSFTBuffer):
"""Construct the C++ backward task object. Backend-specific."""
...
@abstractmethod
def load_weights(self, physical_to_logical_map_cpu: torch.Tensor) -> None:
...
@abstractmethod
def init_lora_weights(
self,
gate_lora_a: torch.Tensor, gate_lora_b: torch.Tensor,
up_lora_a: torch.Tensor, up_lora_b: torch.Tensor,
down_lora_a: torch.Tensor, down_lora_b: torch.Tensor,
grad_gate_lora_a: torch.Tensor, grad_gate_lora_b: torch.Tensor,
grad_up_lora_a: torch.Tensor, grad_up_lora_b: torch.Tensor,
grad_down_lora_a: torch.Tensor, grad_down_lora_b: torch.Tensor,
) -> None:
...
@abstractmethod
def update_lora_weights(self) -> None:
...
# ========== Buffer helpers ==========
def _get_buffer(self, qlen: int) -> KExpertsSFTBuffer:
return KExpertsSFTBuffer.get_buffer(
qlen=qlen,
hidden_size=self.hidden_size,
moe_intermediate_size=self.moe_intermediate_size,
num_experts=self.num_experts,
num_experts_per_tok=self.num_experts_per_tok,
lora_rank=self.lora_rank,
dtype=torch.bfloat16,
)
def _validate_forward_inputs(self, hidden_states: torch.Tensor, expert_ids: torch.Tensor, weights: torch.Tensor):
if not self._weights_loaded:
raise RuntimeError("Weights not loaded. Call load_weights() or load_weights_from_tensors() first.")
if not self._lora_initialized and not self._is_skip_lora:
raise RuntimeError("LoRA weights not initialized. Call init_lora_weights() first.")
qlen = hidden_states.shape[0]
if qlen > self.chunked_prefill_size:
raise ValueError(
f"qlen ({qlen}) exceeds chunked_prefill_size ({self.chunked_prefill_size}). "
"Increase chunked_prefill_size or reduce qlen to avoid buffer overrun."
)
if expert_ids.shape[0] != qlen or expert_ids.shape[1] != self.num_experts_per_tok:
raise ValueError(
f"expert_ids shape {tuple(expert_ids.shape)} must be ({qlen}, {self.num_experts_per_tok})."
)
if weights.shape[0] != qlen or weights.shape[1] != self.num_experts_per_tok:
raise ValueError(
f"weights shape {tuple(weights.shape)} must be ({qlen}, {self.num_experts_per_tok})."
)
def _copy_inputs_to_buffer(self, buffer: KExpertsSFTBuffer, hidden_states: torch.Tensor,
expert_ids: torch.Tensor, weights: torch.Tensor, qlen: int) -> torch.device:
"""Copy inputs to CPU buffer, return input device."""
input_device = hidden_states.device
buffer.input_cpu[:qlen].copy_(hidden_states.to(torch.bfloat16), non_blocking=True)
buffer.expert_ids_cpu[:qlen].copy_(expert_ids.to(torch.int64), non_blocking=True)
buffer.weights_cpu[:qlen].copy_(weights.to(torch.float32), non_blocking=True)
buffer.bsz_tensor[0] = qlen
if input_device.type == "cuda":
torch.cuda.synchronize(input_device)
return input_device
def _copy_grad_output_to_cpu(self, buffer: KExpertsSFTBuffer, grad_output: torch.Tensor, qlen: int):
"""Copy grad_output to CPU buffer."""
input_device = grad_output.device
if input_device.type == "cuda":
torch.cuda.synchronize(input_device)
buffer.grad_output_cpu[:qlen].copy_(grad_output.to(torch.bfloat16))
def _return_output(self, buffer: KExpertsSFTBuffer, qlen: int, output_device: Optional[torch.device]):
if output_device is not None:
return buffer.output_cpu[:qlen].to(device=output_device, non_blocking=True)
else:
return buffer.output_cpu[:qlen].clone()
def _return_grads(self, buffer: KExpertsSFTBuffer, qlen: int, output_device: Optional[torch.device]):
if output_device is not None:
grad_input = buffer.grad_input_cpu[:qlen].to(device=output_device, non_blocking=True)
grad_weights = buffer.grad_weights[:qlen].to(device=output_device, non_blocking=True)
else:
grad_input = buffer.grad_input_cpu[:qlen].clone()
grad_weights = buffer.grad_weights[:qlen].clone()
return grad_input, grad_weights
# ========== Concrete forward/backward ==========
def forward(
self,
hidden_states: torch.Tensor,
expert_ids: torch.Tensor,
weights: torch.Tensor,
save_for_backward: bool = True,
output_device: Optional[torch.device] = None,
) -> torch.Tensor:
"""Synchronous forward pass with optional gradient caching."""
self._validate_forward_inputs(hidden_states, expert_ids, weights)
qlen = hidden_states.shape[0]
buffer = self._get_buffer(qlen)
self._copy_inputs_to_buffer(buffer, hidden_states, expert_ids, weights, qlen)
self.cpu_infer.submit(self._make_forward_task(buffer, save_for_backward))
self.cpu_infer.sync()
if save_for_backward and self._cache_depth == 0:
self._cache_depth += 1
return self._return_output(buffer, qlen, output_device)
def backward(
self,
grad_output: torch.Tensor,
output_device: Optional[torch.device] = None,
) -> Tuple[torch.Tensor, torch.Tensor]:
"""Backward pass computing grad_input and grad_weights."""
if self._cache_depth <= 0:
raise RuntimeError("No forward cache available. Call forward(save_for_backward=True) first.")
qlen = grad_output.shape[0]
buffer = self._get_buffer(qlen)
self._copy_grad_output_to_cpu(buffer, grad_output, qlen)
self.cpu_infer.submit(self._make_backward_task(buffer))
self.cpu_infer.sync()
self._cache_depth -= 1
return self._return_grads(buffer, qlen, output_device)
# ========== Async forward ==========
def submit_forward(
self,
hidden_states: torch.Tensor,
expert_ids: torch.Tensor,
weights: torch.Tensor,
save_for_backward: bool = True,
) -> None:
"""Submit forward pass asynchronously (non-blocking). Call sync_forward() to get results."""
self._validate_forward_inputs(hidden_states, expert_ids, weights)
qlen = hidden_states.shape[0]
buffer = self._get_buffer(qlen)
self._copy_inputs_to_buffer(buffer, hidden_states, expert_ids, weights, qlen)
self._pending_buffer = buffer
self._pending_save_for_backward = save_for_backward
self._pending_qlen = qlen
self.cpu_infer.submit(self._make_forward_task(buffer, save_for_backward))
def sync_forward(self, output_device: Optional[torch.device] = None) -> torch.Tensor:
"""Synchronize and retrieve forward results. Must be called after submit_forward()."""
if not hasattr(self, "_pending_buffer") or self._pending_buffer is None:
raise RuntimeError("No pending forward. Call submit_forward() first.")
self.cpu_infer.sync()
buffer = self._pending_buffer
save_for_backward = self._pending_save_for_backward
qlen = self._pending_qlen
if save_for_backward and self._cache_depth == 0:
self._cache_depth += 1
self._pending_buffer = None
self._pending_save_for_backward = None
self._pending_qlen = None
return self._return_output(buffer, qlen, output_device)
# ========== Async backward ==========
def submit_backward_async(
self,
grad_output: torch.Tensor,
output_device: Optional[torch.device] = None,
) -> None:
"""Submit backward task without waiting. Call sync_backward() for results."""
if self._cache_depth <= 0:
raise RuntimeError("No forward cache available. Call forward(save_for_backward=True) first.")
qlen = grad_output.shape[0]
buffer = self._get_buffer(qlen)
self._copy_grad_output_to_cpu(buffer, grad_output, qlen)
self.cpu_infer.submit(self._make_backward_task(buffer))
self._async_bwd_qlen = qlen
self._async_bwd_output_device = output_device
def sync_backward(self) -> Tuple[torch.Tensor, torch.Tensor]:
"""Wait for async backward and return results."""
self.cpu_infer.sync()
qlen = self._async_bwd_qlen
output_device = self._async_bwd_output_device
buffer = self._get_buffer(qlen)
self._cache_depth -= 1
return self._return_grads(buffer, qlen, output_device)
# ========== Backward repack (optional, subclasses may override) ==========
def submit_backward_repack(self):
if not self._weights_loaded or self.moe is None:
return
if hasattr(self.moe, 'submit_backward_repack'):
self.moe.submit_backward_repack()
def wait_backward_repack(self):
if not self._weights_loaded or self.moe is None:
return
if hasattr(self.moe, 'wait_backward_repack'):
self.moe.wait_backward_repack()