Merge pull request 'finish TripletMarginWithDistanceLoss #39' (#67) from gsd123/GPUCodeForces:TripletMarginWithDistanceLoss into main

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Kuohais 2025-11-13 09:46:36 +08:00
commit 97bf31d39e
4 changed files with 409 additions and 0 deletions

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import torch
import torch.nn as nn
from torch.utils.cpp_extension import load_inline
N, D = 32, 128
assert D % 4 == 0, "Embedding dimension D must be a multiple of 4 for vectorization"
class ModelNew(nn.Module):
def __init__(self, margin=1.0, swap=False):
super().__init__()
self.margin = float(margin)
self.swap = swap
self.block_size = 256
self._compile_cuda_kernel()
def _compile_cuda_kernel(self):
cpp_source = """
#include <torch/extension.h>
torch::Tensor triplet_forward_cuda(
torch::Tensor anchor,
torch::Tensor positive,
torch::Tensor negative,
float margin,
bool swap,
int N,
int D);
"""
cuda_source = f"""
#include <cuda_runtime.h>
#include <cmath>
#define BLOCK_SIZE {self.block_size}
#define WARP_SIZE 32
// Warp 归约工具
__inline__ __device__ float warp_reduce_sum(float val) {{
#pragma unroll
for (int offset = WARP_SIZE / 2; offset > 0; offset /= 2) {{
val += __shfl_down_sync(0xffffffff, val, offset);
}}
return val;
}}
__global__ void triplet_l2_kernel(
const float* __restrict__ anchor,
const float* __restrict__ positive,
const float* __restrict__ negative,
float* __restrict__ output,
float margin,
bool swap,
int D_vec // D / 4
) {{
const int n_idx = blockIdx.x;
const int tid = threadIdx.x;
const int offset = n_idx * D_vec * 4;
const float4* a_ptr = reinterpret_cast<const float4*>(anchor + offset);
const float4* p_ptr = reinterpret_cast<const float4*>(positive + offset);
const float4* n_ptr = reinterpret_cast<const float4*>(negative + offset);
float sum_sq_ap = 0.0f;
float sum_sq_an = 0.0f;
float sum_sq_pn = 0.0f;
for (int i = tid; i < D_vec; i += BLOCK_SIZE) {{
float4 a = __ldg(&a_ptr[i]);
float4 p = __ldg(&p_ptr[i]);
float4 n = __ldg(&n_ptr[i]);
float4 diff_ap, diff_an, diff_pn;
diff_ap.x = a.x - p.x; diff_ap.y = a.y - p.y; diff_ap.z = a.z - p.z; diff_ap.w = a.w - p.w;
diff_an.x = a.x - n.x; diff_an.y = a.y - n.y; diff_an.z = a.z - n.z; diff_an.w = a.w - n.w;
sum_sq_ap += diff_ap.x*diff_ap.x + diff_ap.y*diff_ap.y + diff_ap.z*diff_ap.z + diff_ap.w*diff_ap.w;
sum_sq_an += diff_an.x*diff_an.x + diff_an.y*diff_an.y + diff_an.z*diff_an.z + diff_an.w*diff_an.w;
if (swap) {{
diff_pn.x = p.x - n.x; diff_pn.y = p.y - n.y; diff_pn.z = p.z - n.z; diff_pn.w = p.w - n.w;
sum_sq_pn += diff_pn.x*diff_pn.x + diff_pn.y*diff_pn.y + diff_pn.z*diff_pn.z + diff_pn.w*diff_pn.w;
}}
}}
__shared__ float shared_data[32][3];
int lane = tid % WARP_SIZE;
int wid = tid / WARP_SIZE;
sum_sq_ap = warp_reduce_sum(sum_sq_ap);
sum_sq_an = warp_reduce_sum(sum_sq_an);
if (swap) sum_sq_pn = warp_reduce_sum(sum_sq_pn);
if (lane == 0) {{
shared_data[wid][0] = sum_sq_ap;
shared_data[wid][1] = sum_sq_an;
if (swap) shared_data[wid][2] = sum_sq_pn;
}}
__syncthreads();
if (wid == 0) {{
sum_sq_ap = (tid < blockDim.x / WARP_SIZE) ? shared_data[lane][0] : 0.0f;
sum_sq_an = (tid < blockDim.x / WARP_SIZE) ? shared_data[lane][1] : 0.0f;
sum_sq_pn = (tid < blockDim.x / WARP_SIZE && swap) ? shared_data[lane][2] : 0.0f;
sum_sq_ap = warp_reduce_sum(sum_sq_ap);
sum_sq_an = warp_reduce_sum(sum_sq_an);
if (swap) sum_sq_pn = warp_reduce_sum(sum_sq_pn);
if (tid == 0) {{
// 开根号得到 L2 距离 (加上 epsilon 防止梯度爆炸通常在backward处理前向计算通常加个极小值)
float dist_ap = sqrtf(sum_sq_ap + 1e-8f);
float dist_an = sqrtf(sum_sq_an + 1e-8f);
if (swap) {{
float dist_pn = sqrtf(sum_sq_pn + 1e-8f);
if (dist_pn < dist_an) {{
dist_an = dist_pn;
}}
}}
// loss = max(d_ap - d_an + margin, 0)
float loss = fmaxf(dist_ap - dist_an + margin, 0.0f);
output[n_idx] = loss;
}}
}}
}}
torch::Tensor triplet_forward_cuda(
torch::Tensor anchor,
torch::Tensor positive,
torch::Tensor negative,
float margin,
bool swap,
int N,
int D)
{{
anchor = anchor.contiguous();
positive = positive.contiguous();
negative = negative.contiguous();
auto output = torch::empty({{N}}, anchor.options());
int D_vec = D / 4;
dim3 blocks(N);
dim3 threads(BLOCK_SIZE);
triplet_l2_kernel<<<blocks, threads>>>(
anchor.data_ptr<float>(),
positive.data_ptr<float>(),
negative.data_ptr<float>(),
output.data_ptr<float>(),
margin,
swap,
D_vec
);
return output;
}}
"""
self.op = load_inline(
name='triplet_loss_cuda_v1',
cpp_sources=cpp_source,
cuda_sources=cuda_source,
functions=['triplet_forward_cuda'],
extra_cuda_cflags=['-O3', '--use_fast_math'],
verbose=False
)
def forward(self, a: torch.Tensor, p: torch.Tensor, n: torch.Tensor) -> torch.Tensor:
if not a.is_cuda: a = a.cuda()
if not p.is_cuda: p = p.cuda()
if not n.is_cuda: n = n.cuda()
N, D = a.shape
losses = self.op.triplet_forward_cuda(a, p, n, self.margin, self.swap, N, D)
return losses.mean()

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import torch
import torch.nn as nn
import torch.nn.functional as F
N, D = 32, 128
class TripletMarginWithDistanceLoss(nn.Module):
def __init__(self, distance_function=None, margin=1.0, swap=False, reduction='mean'):
super().__init__()
self.distance_function = distance_function if distance_function is not None else nn.PairwiseDistance()
self.margin = margin
self.swap = swap
self.reduction = reduction
def forward(self, anchor: torch.Tensor, positive: torch.Tensor, negative: torch.Tensor) -> torch.Tensor:
d_ap = self.distance_function(anchor, positive)
d_an = self.distance_function(anchor, negative)
if self.swap:
d_pn = self.distance_function(positive, negative)
d_an = torch.min(d_an, d_pn)
loss = torch.clamp(d_ap - d_an + self.margin, min=0.0)
if self.reduction == 'mean':
return loss.mean()
elif self.reduction == 'sum':
return loss.sum()
else: # 'none'
return loss
class Model(nn.Module):
def __init__(self, margin=1.0, swap=False):
super().__init__()
self.op = TripletMarginWithDistanceLoss(distance_function=nn.PairwiseDistance(), margin=margin, swap=swap)
def forward(self, a: torch.Tensor, p: torch.Tensor, n: torch.Tensor) -> torch.Tensor:
return self.op(a, p, n)
def get_inputs():
anchor = torch.randn(N, D, dtype=torch.float32)
positive = torch.randn(N, D, dtype=torch.float32)
negative = torch.randn(N, D, dtype=torch.float32)
return [anchor, positive, negative]
def get_init_inputs():
return [1.0, False]

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You write custom CUDA kernels to replace the PyTorch operators in the given EvoNorm architecture to get speedups.
You have complete freedom to choose the set of operators you want to replace. You may make the decision to replace some operators with custom CUDA kernels and leave others unchanged. You may replace multiple operators with custom implementations, consider operator fusion opportunities (combining multiple operators into a single kernel, for example, combining normalization+affine_transform+nonlinear_gating), or algorithmic changes (such as optimized memory access patterns). You are only limited by your imagination.
Technical Overview: CUDA-Optimized Triplet Margin Loss with L2 Distance
This implementation provides a high-performance CUDA kernel for computing triplet loss, designed for deep metric learning applications with optimized parallel computation and memory access patterns.
Key Features:
Architecture:
Custom CUDA kernel with inline compilation using PyTorch C++ extensions
Optimized for NVIDIA GPUs with warp-level parallelism and shared memory utilization
Supports 4-element vectorization (float4) for memory coalescing
Implements both standard and "swap" variants of triplet loss
Performance Optimizations:
Vectorized Memory Access: Uses float4 data type to load 4 elements per instruction
Coalesced Memory Reads: Contiguous memory access through __ldgintrinsic
Warp Reduction: Efficient warp-level reduction operations using __shfl_down_sync
Shared Memory: Intermediate results stored in shared memory for block-level reduction
Branch Optimization: Conditional swap computation handled efficiently
Kernel Specifications:
Block size: 256 threads
Warp size: 32 threads
Grid dimension: N (batch size)
Input requirement: Embedding dimension D must be divisible by 4
Here's an example to show you the syntax of inline embedding custom CUDA operators in torch: The example given architecture is:
import torch
import torch.nn as nn
import torch.nn.functional as F
N, D = 32, 128
class TripletMarginWithDistanceLoss(nn.Module):
def __init__(self, distance_function=None, margin=1.0, swap=False, reduction='mean'):
super().__init__()
self.distance_function = distance_function if distance_function is not None else nn.PairwiseDistance()
self.margin = margin
self.swap = swap
self.reduction = reduction
def forward(self, anchor: torch.Tensor, positive: torch.Tensor, negative: torch.Tensor) -> torch.Tensor:
d_ap = self.distance_function(anchor, positive)
d_an = self.distance_function(anchor, negative)
if self.swap:
d_pn = self.distance_function(positive, negative)
d_an = torch.min(d_an, d_pn)
loss = torch.clamp(d_ap - d_an + self.margin, min=0.0)
if self.reduction == 'mean':
return loss.mean()
elif self.reduction == 'sum':
return loss.sum()
else: # 'none'
return loss
class Model(nn.Module):
def __init__(self, margin=1.0, swap=False):
super().__init__()
self.op = TripletMarginWithDistanceLoss(distance_function=nn.PairwiseDistance(), margin=margin, swap=swap)
def forward(self, a: torch.Tensor, p: torch.Tensor, n: torch.Tensor) -> torch.Tensor:
return self.op(a, p, n)
def get_inputs():
anchor = torch.randn(N, D, dtype=torch.float32)
positive = torch.randn(N, D, dtype=torch.float32)
negative = torch.randn(N, D, dtype=torch.float32)
return [anchor, positive, negative]
def get_init_inputs():
return [1.0, False] # margin, swap

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###########################################################
# 性能和精度验证程序
###########################################################
import torch
import torch.nn as nn
import time
from TripletMarginWithDistanceLoss_torch import Model, get_inputs, get_init_inputs
from TripletMarginWithDistanceLoss_cuda import ModelNew
def run_benchmark():
# 检查 CUDA 是否可用
if not torch.cuda.is_available():
print("CUDA 不可用,请确保您有可用的 NVIDIA GPU 并已正确安装 PyTorch CUDA 版本。")
return
else:
device = torch.device("cuda")
# 初始化模型
init_inputs = get_init_inputs()
init_inputs = [
x.cuda(device=device) if isinstance(x, torch.Tensor) else x for x in init_inputs
]
inputs = get_inputs()
inputs = [
x.cuda(device=device) if isinstance(x, torch.Tensor) else x for x in inputs
]
torch_model = Model(*init_inputs).cuda()
cuda_model = ModelNew(*init_inputs).cuda()
torch_model.eval()
cuda_model.eval()
print("-------------------- 精度对齐验证 --------------------")
with torch.no_grad():
output_torch = torch_model(*inputs)
output_cuda = cuda_model(*inputs)
precision_flag = torch.allclose(output_torch, output_cuda, rtol=1e-03)
if precision_flag:
print("✅ 精度对齐:两个模型的输出结果非常接近。")
else:
print("❌ 精度不一致!")
print("\n-------------------- 性能加速比测试 --------------------")
num_iterations = 100
# PyTorch 模型计时
torch.cuda.synchronize()
start_time = time.time()
for _ in range(num_iterations):
_ = torch_model(*inputs)
torch.cuda.synchronize()
torch_time = (time.time() - start_time) / num_iterations
# 自定义 CUDA 内核计时
torch.cuda.synchronize()
start_time = time.time()
for _ in range(num_iterations):
_ = cuda_model(*inputs)
torch.cuda.synchronize()
cuda_time = (time.time() - start_time) / num_iterations
print(f"PyTorch torch.relu 平均执行时间: {torch_time:.6f}")
print(f"自定义 CUDA 内核 平均执行时间: {cuda_time:.6f}")
speedup = 0
if cuda_time > 0:
speedup = torch_time / cuda_time
print(f"加速比 (Speedup): {speedup:.2f}x")
else:
print("CUDA 内核执行时间为0无法计算加速比。")
return precision_flag, speedup
if __name__ == "__main__":
precision_flag, speedup = run_benchmark()