cann组织链接https://atomgit.com/cann
ops-nn仓库链接https://atomgit.com/cann/
ops
-nn


本文导读

本文提供ops-nn算子开发的完整实战指南,从算子设计、实现、测试到
部署
的全流程讲解。通过实际案例,帮助开发者掌握在CANN平台上开发高性能算子的完整技能链。本文将覆盖算子规范、AscendC编程、性能调优、以及与深度学习框架的集成等关键环节。

CANN算子开发平台

CANN(Compute Architecture for Neural Networks)为开发者提供了完善的算子开发工具链,包括AscendC编程语言、编译工具、
仿真
器、性能分析器等。通过CANN提供的开发套件,开发者可以充分利用昇腾AI处理器的硬件特性,实现高效的算子实现。

ops-nn算子库 架构

ops-nn作为CANN的核心算子库,采用了清晰的分层架构:从底层的
kernel
实现(op_kernel)、主机端调度(op_host)、API封装(op_api)到图层优化(op_graph),每一层都有明确的职责和接口规范。理解这种架构是进行算子开发的基础。

算子开发全流程

第一步: 需求分析 与设计

确定算子功能

以自定义的FusedAttention算子为例:

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# 功能:融合的多头注意力
# 输入:
# - Q, K, V: [batch, seq_len, num_heads, head_dim]
# - mask: [batch, seq_len, seq_len]
# - scale: float
# 输出:
# - attention_output: [batch, seq_len, num_heads, head_dim]
# - attention_weights: [batch, num_heads, seq_len, seq_len]

def fused_attention(Q, K, V, mask, scale):
# QK^T / sqrt(d_k)
scores = torch.matmul(Q, K.transpose(-2, -1)) * scale

# 加mask
scores = scores + mask

# Softmax
attn_weights = torch.softmax(scores, dim=-1)

# 加权求和
output = torch.matmul(attn_weights, V)

return output, attn_weights





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

算子规范设计

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// fused_attention.h
namespace custom_ops {

// 算子接口
aclnnStatus aclnnFusedAttention(
const aclTensor* query, // 输入Q
const aclTensor* key, // 输入K
const aclTensor* value, // 输入V
const aclTensor* mask, // 注意力mask
float scale, // 缩放因子
aclTensor* output, // 输出
aclTensor* attn_weights, // 注意力权重
aclrtStream stream // CANN流
);

} // namespace custom_ops





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

性能目标

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目标1:融合后的性能优于分开调用5个算子
目标2:大batch(batch>=32)下,吞吐量提升50%
目标3:内存占用减少30%(避免中间结果存储)


第二步:Kernel实现

创建算子目录结构

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ops-nn/
└── fused_attention/
├── op_kernel/
│ ├── fused_attention.h # Kernel头文件
│ └── fused_attention.cpp # Kernel实现
├── op_host/
│ └── fused_attention_host.cpp # 主机端实现
├── op_api/
│ └── fused_attention_api.cpp # API封装
└── test/
└── test_fused_attention.cpp # 单元测试





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

Kernel头文件

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// op_kernel/fused_attention.h
#pragma once
#include "kernel_operator.h"

namespace AscendC {

template<typename T>
class FusedAttention {
public:
__aicore__ inline FusedAttention() {}

__aicore__ inline void Init(
GM_ADDR query,
GM_ADDR key,
GM_ADDR value,
GM_ADDR mask,
GM_ADDR output,
GM_ADDR attn_weights,
const FusedAttentionTilingData* tiling
);

__aicore__ inline void Process();

private:
__aicore__ inline void ComputeScores();
__aicore__ inline void ApplyMaskAndSoftmax();
__aicore__ inline void ComputeOutput();

// 全局内存地址
GlobalTensor<T> query_gm;
GlobalTensor<T> key_gm;
GlobalTensor<T> value_gm;
GlobalTensor<T> mask_gm;
GlobalTensor<T> output_gm;
GlobalTensor<T> attn_weights_gm;

// Tiling参数
FusedAttentionTilingData tiling_data;

// 本地内存缓冲区
TPipe pipe;
LocalTensor<T> query_local;
LocalTensor<T> key_local;
LocalTensor<T> value_local;
LocalTensor<T> scores_local;
LocalTensor<T> softmax_local;
LocalTensor<T> output_local;
};

} // namespace AscendC





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

Kernel实现

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// op_kernel/fused_attention.cpp
#include "fused_attention.h"

namespace AscendC {

template<typename T>
__aicore__ inline void FusedAttention<T>::Init(
GM_ADDR query,
GM_ADDR key,
GM_ADDR value,
GM_ADDR mask,
GM_ADDR output,
GM_ADDR attn_weights,
const FusedAttentionTilingData* tiling
) {
// 初始化全局内存
query_gm.SetGlobalBuffer((__gm__ T*)query);
key_gm.SetGlobalBuffer((__gm__ T*)key);
value_gm.SetGlobalBuffer((__gm__ T*)value);
mask_gm.SetGlobalBuffer((__gm__ T*)mask);
output_gm.SetGlobalBuffer((__gm__ T*)output);
attn_weights_gm.SetGlobalBuffer((__gm__ T*)attn_weights);

// 保存tiling参数
tiling_data = *tiling;

// 初始化pipeline
pipe.InitBuffer(inQueueQ, 1, tiling_data.tile_size_q);
pipe.InitBuffer(inQueueK, 1, tiling_data.tile_size_k);
pipe.InitBuffer(inQueueV, 1, tiling_data.tile_size_v);
pipe.InitBuffer(outQueue, 1, tiling_data.tile_size_out);
}

template<typename T>
__aicore__ inline void FusedAttention<T>::ComputeScores() {
// 计算 Q @ K^T
uint32_t batch = tiling_data.batch;
uint32_t seq_len = tiling_data.seq_len;
uint32_t head_dim = tiling_data.head_dim;

for (uint32_t b = 0; b < batch; b++) {
for (uint32_t i = 0; i < seq_len; i += TILE_SEQ) {
// 加载Q的一个tile
DataCopy(query_local, query_gm[b * seq_len * head_dim + i * head_dim],
TILE_SEQ * head_dim);

for (uint32_t j = 0; j < seq_len; j += TILE_SEQ) {
// 加载K的一个tile
DataCopy(key_local, key_gm[b * seq_len * head_dim + j * head_dim],
TILE_SEQ * head_dim);

// 矩阵乘法:Q @ K^T
MatMul(scores_local, query_local, key_local,
TILE_SEQ, head_dim, TILE_SEQ, true); // transpose K

// 缩放
Muls(scores_local, scores_local, tiling_data.scale, TILE_SEQ * TILE_SEQ);

// 保存scores
DataCopy(attn_weights_gm[b * seq_len * seq_len + i * seq_len + j],
scores_local, TILE_SEQ * TILE_SEQ);
}
}
}
}

template<typename T>
__aicore__ inline void FusedAttention<T>::ApplyMaskAndSoftmax() {
uint32_t batch = tiling_data.batch;
uint32_t seq_len = tiling_data.seq_len;

for (uint32_t b = 0; b < batch; b++) {
for (uint32_t i = 0; i < seq_len; i++) {
// 加载scores的一行
DataCopy(scores_local,
attn_weights_gm[b * seq_len * seq_len + i * seq_len],
seq_len);

// 加载mask
DataCopy(mask_local,
mask_gm[b * seq_len * seq_len + i * seq_len],
seq_len);

// 加mask
Add(scores_local, scores_local, mask_local, seq_len);

// Softmax
// 1. 找最大值
T max_val = ReduceMax(scores_local, seq_len);

// 2. exp(x - max)
Subs(scores_local, scores_local, max_val, seq_len);
Exp(scores_local, scores_local, seq_len);

// 3. 求和
T sum = ReduceSum(scores_local, seq_len);

// 4. 归一化
Divs(softmax_local, scores_local, sum, seq_len);

// 写回
DataCopy(attn_weights_gm[b * seq_len * seq_len + i * seq_len],
softmax_local, seq_len);
}
}
}

template<typename T>
__aicore__ inline void FusedAttention<T>::ComputeOutput() {
// 计算 attn_weights @ V
uint32_t batch = tiling_data.batch;
uint32_t seq_len = tiling_data.seq_len;
uint32_t head_dim = tiling_data.head_dim;

for (uint32_t b = 0; b < batch; b++) {
for (uint32_t i = 0; i < seq_len; i++) {
// 加载attention weights的一行
DataCopy(softmax_local,
attn_weights_gm[b * seq_len * seq_len + i * seq_len],
seq_len);

// 初始化输出
Duplicate(output_local, (T)0, head_dim);

// 加权求和
for (uint32_t j = 0; j < seq_len; j++) {
// 加载V的一行
DataCopy(value_local,
value_gm[b * seq_len * head_dim + j * head_dim],
head_dim);

// output += weight * V
T weight = softmax_local[j];
Axpy(output_local, value_local, weight, head_dim);
}

// 写回输出
DataCopy(output_gm[b * seq_len * head_dim + i * head_dim],
output_local, head_dim);
}
}
}

template<typename T>
__aicore__ inline void FusedAttention<T>::Process() {
// 三阶段计算
ComputeScores(); // Q @ K^T
ApplyMaskAndSoftmax(); // Mask + Softmax
ComputeOutput(); // Attn @ V
}

} // namespace AscendC

// 实例化模板
extern "C" __global__ __aicore__ void fused_attention_kernel(
GM_ADDR query,
GM_ADDR key,
GM_ADDR value,
GM_ADDR mask,
GM_ADDR output,
GM_ADDR attn_weights,
GM_ADDR tiling_gm
) {
AscendC::FusedAttention<half> op;
op.Init(query, key, value, mask, output, attn_weights,
(FusedAttentionTilingData*)tiling_gm);
op.Process();
}





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

第三步:主机端实现

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// op_host/fused_attention_host.cpp
#include "aclnn_base.h"
#include "fused_attention_tiling.h"

namespace op_host {

// Tiling计算
void CalculateTiling(const aclTensor* query,
const aclTensor* key,
FusedAttentionTilingData* tiling) {
// 获取输入shape
auto shape = aclGetTensorShape(query);
tiling->batch = aclGetDimSize(shape, 0);
tiling->seq_len = aclGetDimSize(shape, 1);
tiling->num_heads = aclGetDimSize(shape, 2);
tiling->head_dim = aclGetDimSize(shape, 3);

// 计算tile大小(根据L1 Buffer大小)
const uint32_t L1_BUFFER_SIZE = 256 * 1024; // 256KB
uint32_t elem_size = sizeof(half);

// 每个tile最多占用L1的1/4
uint32_t max_tile_elements = L1_BUFFER_SIZE / 4 / elem_size;

// 计算seq_len的tile大小
tiling->tile_seq = std::min(tiling->seq_len,
static_cast<uint32_t>(sqrt(max_tile_elements)));

// 计算需要的block数量
tiling->num_blocks = (tiling->batch * tiling->num_heads +
GetCoreNum() - 1) / GetCoreNum();

// 计算scale
tiling->scale = 1.0f / sqrt(static_cast<float>(tiling->head_dim));
}

// 主机端算子实现
aclnnStatus aclnnFusedAttentionGetWorkspaceSize(
const aclTensor* query,
const aclTensor* key,
const aclTensor* value,
const aclTensor* mask,
float scale,
const aclTensor* output,
const aclTensor* attn_weights,
uint64_t* workspaceSize,
aclOpExecutor** executor
) {
// 计算tiling
FusedAttentionTilingData tiling;
CalculateTiling(query, key, &tiling);
tiling.scale = scale;

// workspace大小 = tiling数据大小
*workspaceSize = sizeof(FusedAttentionTilingData);

// 创建executor
*executor = CreateOpExecutor("FusedAttention", &tiling, sizeof(tiling));

return ACL_SUCCESS;
}

aclnnStatus aclnnFusedAttention(
void* workspace,
uint64_t workspaceSize,
aclOpExecutor* executor,
aclrtStream stream
) {
// 获取tiling数据
auto* tiling = reinterpret_cast<FusedAttentionTilingData*>(workspace);

// 获取输入输出地址
auto query_addr = GetTensorDeviceAddr(executor, "query");
auto key_addr = GetTensorDeviceAddr(executor, "key");
auto value_addr = GetTensorDeviceAddr(executor, "value");
auto mask_addr = GetTensorDeviceAddr(executor, "mask");
auto output_addr = GetTensorDeviceAddr(executor, "output");
auto attn_weights_addr = GetTensorDeviceAddr(executor, "attn_weights");

// 拷贝tiling到设备
GM_ADDR tiling_gm = AllocDeviceMemory(workspaceSize, stream);
aclrtMemcpy(tiling_gm, workspaceSize, tiling, workspaceSize,
ACL_MEMCPY_HOST_TO_DEVICE);

// 启动kernel
uint32_t block_dim = tiling->num_blocks;
LaunchKernel("fused_attention_kernel",
block_dim,
query_addr, key_addr, value_addr, mask_addr,
output_addr, attn_weights_addr, tiling_gm,
stream);

// 释放临时内存
FreeDeviceMemory(tiling_gm, stream);

return ACL_SUCCESS;
}

} // namespace op_host





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

第四步:API封装

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// op_api/fused_attention_api.cpp
#include "aclnn/aclnn_fused_attention.h"

extern "C" {

aclnnStatus aclnnFusedAttention(
const aclTensor* query,
const aclTensor* key,
const aclTensor* value,
const aclTensor* mask,
float scale,
aclTensor* output,
aclTensor* attn_weights,
aclrtStream stream
) {
// 1. 参数校验
CHECK_TENSOR_NOT_NULL(query);
CHECK_TENSOR_NOT_NULL(key);
CHECK_TENSOR_NOT_NULL(value);
CHECK_TENSOR_NOT_NULL(output);

// 2. Shape校验
auto q_shape = aclGetTensorShape(query);
auto k_shape = aclGetTensorShape(key);
auto v_shape = aclGetTensorShape(value);

CHECK_SHAPE_MATCH(q_shape, k_shape);
CHECK_SHAPE_MATCH(q_shape, v_shape);

// 3. 数据类型校验
auto dtype = aclGetTensorDataType(query);
CHECK_DTYPE_SUPPORTED(dtype, {ACL_FLOAT16, ACL_FLOAT});

// 4. 获取workspace大小
uint64_t workspaceSize = 0;
aclOpExecutor* executor = nullptr;

auto ret = op_host::aclnnFusedAttentionGetWorkspaceSize(
query, key, value, mask, scale, output, attn_weights,
&workspaceSize, &executor);
if (ret != ACL_SUCCESS) {
return ret;
}

// 5. 分配workspace
void* workspace = nullptr;
if (workspaceSize > 0) {
workspace = AllocWorkspace(workspaceSize);
}

// 6. 执行算子
ret = op_host::aclnnFusedAttention(
workspace, workspaceSize, executor, stream);

// 7. 清理
if (workspace) {
FreeWorkspace(workspace);
}
DestroyExecutor(executor);

return ret;
}

} // extern "C"





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

第五步:编译部署

编译脚本

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# build_fused_attention.sh
#!/bin/bash

SOC_VERSION="ascend910b"
OPS_NAME="fused_attention"

# 编译kernel
ascendc-compile \
--soc=${SOC_VERSION} \
--kernel_name=fused_attention_kernel \
--input=op_kernel/fused_attention.cpp \
--output=build/${OPS_NAME}_kernel.o

# 编译主机端
g++ -c op_host/fused_attention_host.cpp \
-I${ASCEND_HOME}/include \
-o build/${OPS_NAME}_host.o

# 编译API
g++ -c op_api/fused_attention_api.cpp \
-I${ASCEND_HOME}/include \
-o build/${OPS_NAME}_api.o

# 链接
g++ -shared \
build/${OPS_NAME}_kernel.o \
build/${OPS_NAME}_host.o \
build/${OPS_NAME}_api.o \
-L${ASCEND_HOME}/lib64 \
-lascendcl \
-o build/lib${OPS_NAME}.so

echo "Build completed: build/lib${OPS_NAME}.so"





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

安装部署

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# 安装算子库
sudo cp build/libfused_attention.so ${ASCEND_HOME}/opp/vendors/custom_nn/op_impl/lib/

# 注册算子
cat > fused_attention.json << EOF
{
"op": "FusedAttention",
"input_desc": [
{"name": "query", "param_type": "required"},
{"name": "key", "param_type": "required"},
{"name": "value", "param_type": "required"},
{"name": "mask", "param_type": "optional"}
],
"attr": [
{"name": "scale", "type": "float", "default_value": "1.0"}
],
"output_desc": [
{"name": "output", "param_type": "required"},
{"name": "attn_weights", "param_type": "optional"}
]
}
EOF

sudo cp fused_attention.json ${ASCEND_HOME}/opp/vendors/custom_nn/op_impl/





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

第六步:测试验证

单元测试

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# test/test_fused_attention.py
import torch
import torch_npu

def test_fused_attention_correctness():
"""测试算子正确性"""
batch, seq_len, num_heads, head_dim = 2, 128, 8, 64

# 准备输入
Q = torch.randn(batch, seq_len, num_heads, head_dim, device='npu', dtype=torch.float16)
K = torch.randn(batch, seq_len, num_heads, head_dim, device='npu', dtype=torch.float16)
V = torch.randn(batch, seq_len, num_heads, head_dim, device='npu', dtype=torch.float16)
mask = torch.zeros(batch, seq_len, seq_len, device='npu', dtype=torch.float16)

# 参考实现
scale = 1.0 / (head_dim ** 0.5)
scores_ref = torch.matmul(Q, K.transpose(-2, -1)) * scale
scores_ref = scores_ref + mask
attn_weights_ref = torch.softmax(scores_ref, dim=-1)
output_ref = torch.matmul(attn_weights_ref, V)

# 自定义算子
output_custom, attn_weights_custom = torch_npu.npu_fused_attention(
Q, K, V, mask, scale)

# 对比结果
assert torch.allclose(output_ref, output_custom, rtol=1e-3, atol=1e-3)
assert torch.allclose(attn_weights_ref, attn_weights_custom, rtol=1e-3, atol=1e-3)

print("✓ Correctness test passed")

def test_fused_attention_performance():
"""测试算子性能"""
import time

batch, seq_len, num_heads, head_dim = 32, 512, 12, 64
num_iters = 100

Q = torch.randn(batch, seq_len, num_heads, head_dim, device='npu', dtype=torch.float16)
K = torch.randn(batch, seq_len, num_heads, head_dim, device='npu', dtype=torch.float16)
V = torch.randn(batch, seq_len, num_heads, head_dim, device='npu', dtype=torch.float16)
mask = torch.zeros(batch, seq_len, seq_len, device='npu', dtype=torch.float16)
scale = 1.0 / (head_dim ** 0.5)

# 预热
for _ in range(10):
_ = torch_npu.npu_fused_attention(Q, K, V, mask, scale)
torch_npu.synchronize()

# 测试融合算子
start = time.time()
for _ in range(num_iters):
output, _ = torch_npu.npu_fused_attention(Q, K, V, mask, scale)
torch_npu.synchronize()
fused_time = (time.time() - start) / num_iters

# 测试分开调用
start = time.time()
for _ in range(num_iters):
scores = torch.matmul(Q, K.transpose(-2, -1)) * scale
scores = scores + mask
attn_weights = torch.softmax(scores, dim=-1)
output = torch.matmul(attn_weights, V)
torch_npu.synchronize()
unfused_time = (time.time() - start) / num_iters

speedup = unfused_time / fused_time
print(f"Fused: {fused_time*1000:.2f} ms")
print(f"Unfused: {unfused_time*1000:.2f} ms")
print(f"Speedup: {speedup:.2f}x")

assert speedup > 1.3, f"Speedup {speedup:.2f}x is less than expected 1.3x"
print("✓ Performance test passed")

if __name__ == "__main__":
test_fused_attention_correctness()
test_fused_attention_performance()





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

性能优化 技巧

1. Tiling优化

根据L1 Buffer大小合理切分:

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// 计算最优tile大小
uint32_t CalculateOptimalTileSize(uint32_t seq_len, uint32_t head_dim) {
const uint32_t L1_SIZE = 256 * 1024; // 256KB
const uint32_t ELEM_SIZE = sizeof(half);

// Q tile + K tile + Score tile 都要放入L1
// tile_seq^2 * head_dim * 3 < L1_SIZE
uint32_t max_tile = sqrt(L1_SIZE / (3 * head_dim * ELEM_SIZE));

// 对齐到16的倍数(硬件要求)
max_tile = (max_tile / 16) * 16;

return std::min(max_tile, seq_len);
}





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

2. 双缓冲

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// 双缓冲pipeline
__aicore__ void ProcessWithDoubleBuffer() {
// 加载第一个tile
LoadTile(buffer[0], tile_0);

for (int i = 0; i < num_tiles; i++) {
int curr = i % 2;
int next = (i + 1) % 2;

// 异步加载下一个tile
if (i + 1 < num_tiles) {
LoadTileAsync(buffer[next], tile_{i+1});
}

// 计算当前tile
ComputeTile(buffer[curr]);

// 等待加载完成
WaitLoad();
}
}





![](/img/posts/ops-nn算子开发实战:从设计到部署的完整流程/0e277fd1e3527b618d9c5ae63382b0e5.webp)

3. 向量化

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// 使用向量指令
const int VEC_SIZE = 8; // FP16向量大小

for (int i = 0; i < size; i += VEC_SIZE) {
// 向量化的乘加
VecMuls(output + i, input + i, scale, VEC_SIZE);
}


最佳实践建议

  1. 模块化设计:将复杂算子分解为多个子函数
  2. 充分测试:单元测试、集成测试、压力测试
  3. 性能分析:使用msprof分析瓶颈
  4. 文档完善:API文档、使用示例、性能指标
  5. 版本管理:算子版本控制,保持向后兼容

总结

本文提供了ops-nn算子开发的完整实战流程,从需求分析、设计、实现到测试部署的全链条讲解。通过掌握这套流程,开发者可以:

  1. 理解CANN算子开发的完整链路
  2. 掌握AscendC编程和性能优化技巧
  3. 实现高性能的自定义算子
  4. 将算子集成到深度学习框架

建议开发者:

  • 从简单算子入手,逐步提升难度
  • 充分利用ops-nn现有算子的代码作为参考
  • 重视测试和性能分析
  • 遵循算子开发规范和最佳实践

算子开发是AI系统性能优化的核心技能,掌握这项技能将为构建高效
AI应用
打下坚实基础。