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# Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# The file has been adapted from DeepSeek DeepGEMM project
# Copyright (c) 2025 DeepSeek
# Licensed under the MIT License - https://github.com/deepseek-ai/DeepGEMM/blob/main/LICENSE
from __future__ import annotations
import math
import os
from functools import cache
import paddle
from ..jit import FP8GemmRuntime, build
from .runtime import (
GemmType,
make_2d_tma_a_desc,
make_2d_tma_b_desc,
make_2d_tma_d_desc,
make_2d_tma_scales_desc,
)
from .utils import (
ceil_div,
get_col_major_tma_aligned_tensor,
get_m_alignment_for_contiguous_layout,
get_num_sms,
)
global_empty_tensor = paddle.empty([0], dtype=paddle.int32)
# Todo: Use default stream to accelerate CPU time. Optimize here if use multistream to launch gemm kernel.
global_stream = paddle.device.current_stream().stream_base.cuda_stream
def is_tma_multicast_legal(
shape_dim: int,
block_dim: int,
num_tma_multicast: int,
num_sms: int,
require_divisible: bool = False,
) -> bool:
divisible = (
ceil_div(shape_dim, block_dim) % num_tma_multicast == 0
or not require_divisible
)
return divisible and num_sms % num_tma_multicast == 0
def get_swizzle_mode(block_n: int) -> int:
elem_size = 2
for mode_bytes in (128, 64, 32):
if (block_n * elem_size) % mode_bytes == 0:
return mode_bytes
return 0
def get_block_n_padding_for_smem_d(block_n: int) -> int:
# NOTES: padding is for solving bank conflicts, but wastes shared memory space
elem_size, requirement = 2, (4, 8)
bank_stride = (block_n * elem_size) // 4
padding = (requirement[0] - bank_stride) % requirement[1]
return (
((padding + requirement[1]) if padding < 0 else padding) * 4
) // elem_size
def get_smem_config(
num_stages: int,
k: int,
block_m: int,
block_n: int,
block_k: int = 128,
is_fp32_out: bool = False,
is_wgrad: bool = False,
) -> tuple[int, int, int]:
assert block_k == 128
# Try swizzle first, as it does not waste shared memory
swizzle_mode = get_swizzle_mode(block_n)
block_n_padding = (
get_block_n_padding_for_smem_d(block_n) if swizzle_mode == 0 else 0
)
# NOTES: `scales_b` in a total manner or per-stage manner
smem_d = block_m * (block_n + block_n_padding) * (4 if is_fp32_out else 2)
smem_a_per_stage = block_m * block_k
smem_scales_a_per_stage = block_m * 4
smem_b_per_stage = block_n * block_k
smem_scales_b_per_stage = (
ceil_div(block_n * 4, block_k) * block_k if is_wgrad else 0
)
smem_scales_b = ceil_div(k, block_k) * 4 if not is_wgrad else 0
smem_barrier = num_stages * 8 * 2
smem_size = 0
smem_size += smem_d
smem_size += num_stages * smem_a_per_stage
smem_size += num_stages * smem_scales_a_per_stage
smem_size += num_stages * smem_b_per_stage
smem_size += num_stages * smem_scales_b_per_stage
smem_size += (
ceil_div(smem_scales_b * (1 if block_k % block_n == 0 else 2), 8) * 8
)
smem_size += smem_barrier
# Swizzle and padding are not compatible
assert int(swizzle_mode > 0) + int(block_n_padding > 0) <= 1
return smem_size, swizzle_mode, block_n_padding
@cache
def get_best_configs(
m: int,
n: int,
k: int,
num_groups: int,
num_sms: int,
is_grouped_contiguous: bool = False,
is_grouped_masked: bool = False,
is_fp32_out: bool = False,
is_wgrad: bool = False,
) -> tuple[int, int, int, int, tuple[int, bool], tuple[int, int, int]]:
if not is_grouped_contiguous:
block_ms = (
64,
128,
) + ((256,) if not is_fp32_out else ())
else:
block_ms = (get_m_alignment_for_contiguous_layout(),)
block_ns = tuple(range(16, 129, 8)) + (
(
136,
152,
)
if is_wgrad
else (
144,
160,
)
)
# Avoid bank conflicts for FP32 output
if is_fp32_out:
block_ns = [x for x in block_ns if x % 16 == 8]
fix_wave_saturate = lambda x: num_sms if x == 0 else x
get_num_waves = lambda bm, bn: (
ceil_div(ceil_div(m, bm) * ceil_div(n, bn) * num_groups, num_sms)
if bm
else None
)
get_last_wave_util = lambda bm, bn: fix_wave_saturate(
(ceil_div(m, bm) * ceil_div(n, bn) * num_groups) % num_sms
)
# Decide block sizes by waves
best_block_m, best_block_n = None, None
for block_m in block_ms:
# NOTES: the block sizes cannot be too large, so at least one dim less than 128
for block_n in filter(lambda bn: block_m <= 128 or bn <= 128, block_ns):
success = False
num_waves, best_num_waves = (
get_num_waves(block_m, block_n),
get_num_waves(best_block_m, best_block_n),
)
if best_block_m is None or best_block_n is None:
success = True
elif num_waves < best_num_waves:
success = True
elif num_waves == best_num_waves:
# Check last wave utilization
util = get_last_wave_util(block_m, block_n)
best_util = get_last_wave_util(best_block_m, best_block_n)
success = util > best_util
if util == best_util:
# Case 1: same `block_m`, smaller `block_n` (wasted)
success |= (
block_m == best_block_m and block_n < best_block_n
)
# Case 2: same `block_n`, smaller `block_m` (wasted)
success |= (
block_n == best_block_n and block_m < best_block_m
)
# Case 3: different for both `block_m` and `block_n`, `block_n` larger is better
success |= (
block_m != best_block_m and block_n > best_block_n
)
best_block_m, best_block_n = (
(block_m, block_n) if success else (best_block_m, best_block_n)
)
assert best_block_m is not None and best_block_n is not None
# Always pick the longest one
# NOTES: for double B scales, the best number of stages may be reduced
best_num_stages, best_smem_config, sm90_capacity = None, None, 232448
stage_candidates = tuple(
filter(lambda s: s <= max(k // 128, 1), (8, 7, 6, 5, 4, 3, 2, 1))
)
if 128 % best_block_n != 0 and 128 // math.gcd(128, best_block_n) <= 4:
# Unrolling both stages and `num_former_iters` will cause large code size
stage_candidates = tuple(
filter(lambda s: s <= max(k // 128, 1), (4, 3, 2, 1))
)
for num_stages in stage_candidates:
best_smem_config = get_smem_config(
num_stages,
k,
best_block_m,
best_block_n,
is_fp32_out=is_fp32_out,
is_wgrad=is_wgrad,
)
if best_smem_config[0] <= sm90_capacity:
best_num_stages = num_stages
break
assert best_smem_config is not None
assert best_num_stages is not None
# Decide the number of TMA multicasts and whether broadcast on A
best_tma_multicast_config = (1, True)
# Try to multicast on the larger block side first
# NOTES: currently, grouped masked GEMM only supports multicast on A and requires the number of blocks in the N-direction to be even
is_multicast_legal = {
"A": is_tma_multicast_legal(
n, best_block_n, 2, num_sms, is_grouped_masked
),
"B": is_tma_multicast_legal(m, best_block_m, 2, num_sms)
and not is_grouped_masked,
}
for i in ("A", "B") if best_block_m > best_block_n else ("B", "A"):
if m >= 512 and is_multicast_legal[i]:
best_tma_multicast_config = (2, i == "A")
break
# Recompute the minimal number of SMs required
# NOTES: less L2 cache usage and less GPU frequency drop
num_waves = get_num_waves(best_block_m, best_block_n)
num_min_sms = ceil_div(
ceil_div(m, best_block_m) * ceil_div(n, best_block_n) * num_groups,
num_waves,
)
num_min_sms = (
ceil_div(num_min_sms, best_tma_multicast_config[0])
* best_tma_multicast_config[0]
)
assert num_min_sms <= num_sms
return (
num_min_sms,
best_block_m,
best_block_n,
best_num_stages,
best_tma_multicast_config,
best_smem_config,
)
def gemm_fp8_fp8_bf16_nt(
lhs: tuple[paddle.Tensor, paddle.Tensor],
rhs: tuple[paddle.Tensor, paddle.Tensor],
out: paddle.Tensor,
num_sms: int | None = None,
) -> None:
"""
Perform a normal GEMM with FP8 inputs and BF16 output, with 1x128 LHS scaling and 128x128 RHS scaling.
Requirements:
LHS, RHS, and output tensors must be contiguous in dimension 1, i.e., strides[1] = 1.
The strides[0] of LHS and RHS must be a multiple of 16, and the strides[0] of output must be a multiple of 8.
RHS and RHS scaling factors are required to be transposed.
The LHS scaling tensor requires a TMA-aligned transposed format, if your input does not match the requirement,
this function will do a transposing with a set of slow PaddlePaddle operations.
Arguments:
lhs: the first element is an FP8 tensor (typed `paddle.float8_e4m3fn`) of shape `[m, k]`,
the second element is an FP32 1x128 scaling tensor for LHS of shape `[m, ⌈k / 128⌉]`.
rhs: the first element is an FP8 tensor (typed `paddle.float8_e4m3fn`) of shape `[n, k]`,
the second element is an FP32 128x128 scaling tensor for RHS of shape `[⌈n / 128⌉, ⌈k / 128⌉]`.
out: the BF16 output tensor of shape `[m, n]`, representing the result.
"""
lhs, lhs_scales = lhs
rhs, rhs_scales = rhs
m, k = lhs.shape
n, k_ = rhs.shape
m_, n_ = out.shape
# Type and shape checks
assert m == m_ and n == n_ and k == k_
assert n > 0 and k > 0
assert lhs_scales.shape == [m, ceil_div(k, 128)]
assert rhs_scales.shape == [ceil_div(n, 128), ceil_div(k, 128)]
assert (
lhs.dtype == paddle.float8_e4m3fn and lhs_scales.dtype == paddle.float32
)
assert (
rhs.dtype == paddle.float8_e4m3fn and rhs_scales.dtype == paddle.float32
)
assert out.dtype == paddle.bfloat16
assert lhs.strides[1] == 1 and out.strides[1] == 1 and rhs.strides[1] == 1
# LHS scales must be transposed for TMA loads, but not for RHS scales
# NOTES: `get_col_major_tma_aligned_tensor` may launch a kernel if not processed by previous kernels
lhs_scales = get_col_major_tma_aligned_tensor(lhs_scales)
assert rhs_scales.is_contiguous()
# Do nothing if `m` is zero
if m == 0:
return
# K must be aligned to 128
aligned_k = ceil_div(k, 128) * 128
# Auto-tuning with compilation
if num_sms is None:
num_sms = get_num_sms()
num_sms, block_m, block_n, num_stages, tma_multicast_config, smem_config = (
get_best_configs(m, n, k, 1, num_sms)
)
if int(os.getenv("DG_JIT_KERNELS_DEBUG", 0)):
print(
f"Auto-tuned gemm_fp8_fp8_bf16_nt as num_sms={num_sms}, block_m={block_m}, block_n={block_n}"
)
block_k = 128
num_tma_threads = 128
num_math_threads_per_group = 128
tensor_map_a = make_2d_tma_a_desc(
GemmType.Normal, lhs, m, k, lhs.strides[0], block_m, block_k, 1
)
tensor_map_b = make_2d_tma_b_desc(
GemmType.Normal, rhs, n, k, rhs.strides[0], block_n, block_k, 1
)
tensor_map_d = make_2d_tma_d_desc(
GemmType.Normal,
out,
m,
n,
out.strides[0],
block_m,
block_n,
1,
smem_config[1],
)
tensor_map_scales_a = make_2d_tma_scales_desc(
GemmType.Normal, lhs_scales, m, k, block_m, block_k, 1
)
kwargs = {
# Templated arguments
"GEMM_TYPE": GemmType.Normal,
"NUM_TMA_THREADS": num_tma_threads,
"NUM_MATH_THREADS_PER_GROUP": num_math_threads_per_group,
"M": m,
"N": n,
"K": aligned_k,
"NUM_GROUPS": 1,
"BLOCK_M": block_m,
"BLOCK_N": block_n,
"BLOCK_K": block_k,
"SWIZZLE_D_MODE": smem_config[1],
"BLOCK_N_PADDING": smem_config[2],
"NUM_STAGES": num_stages,
"NUM_TMA_MULTICAST": tma_multicast_config[0],
"IS_TMA_MULTICAST_ON_A": tma_multicast_config[1],
# Runtime arguments
"SCALES_B": rhs_scales,
"GROUPED_LAYOUT": global_empty_tensor,
"NUM_SMS": num_sms,
"SMEM_SIZE": smem_config[0],
"TENSOR_MAP_A": tensor_map_a,
"TENSOR_MAP_B": tensor_map_b,
"TENSOR_MAP_SCALES_A": tensor_map_scales_a,
"TENSOR_MAP_D": tensor_map_d,
"STREAM": global_stream,
"DEVICE_INDEX": out.place.gpu_device_id(),
}
# Generate, build and run the kernel
runtime = build("gemm_fp8_fp8_bf16_nt", FP8GemmRuntime, kwargs)
runtime(**kwargs)