# parallel

**Repository Path**: digitzh/parallel

## Basic Information

- **Project Name**: parallel
- **Description**: 并行计算程序设计
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2024-12-01
- **Last Updated**: 2024-12-02

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# parallel 并行计算

参考链接：[Voter数组元素并行比较 - Gitee Issue](https://gitee.com/tjopenlab/como-fscp-voter/issues/IB81JP)

## 测试方法

执行`./verify.sh`，编译生成可执行文件(目录:bin)、运行，并生成反汇编文件(目录:objdump)。

## 测试结果

使用不同的并行方法对大小为1e8的数组进行比较，将运行时间与普通for循环进行对比。

### 1 O3优化+自动向量化(vectorization)编译标志

普通for循环: 
```
$(CC) -march=native -g -o $(BIN_PATH)/$@ $<
```
O3优化+自动向量化: 
```
$(CC) -O3 -ftree-vectorize -march=native -g $< -o $(BIN_PATH)/$@
```

测试结果示例(设备配置不同，结果可能有差别):

#### C

```sh
[1-SIMD-vec]Starting comparison...
Arrays are equal.
Execution time: 0.585486 seconds
-------------------------------
[1-SIMD-vec]Starting comparison...
Arrays are equal.
Execution time: 0.095347 seconds
```

#### C++

```sh
[1-SIMD-vec]Starting comparison...
Arrays are equal.
Execution time: 0.144578 seconds
-------------------------------
[1-SIMD-vec]Starting comparison...
Arrays are equal.
Execution time: 0.0977148 seconds
```

### 2 内置的SIMD库(AVX...)

普通for循环:0.143194s

SIMD: 0.120148s

AVX2: 0.0978016s
```sh
[2-SIMD-builtin]Starting comparison...
Arrays are equal (normal comparison).
Normal comparison time: 0.143194 seconds
Arrays are equal (SIMD comparison).
SIMD comparison time: 0.120148 seconds
Arrays are equal (AVX2 comparison).
AVX2 comparison time: 0.0978016 seconds
```
可使用CPU-Z查看支持的指令集。实测PC支持AVX2指令集。

相关反汇编调用举例:
```
000000000000149b <_Z19compare_arrays_avx2PKiS0_m>:
    149b:	f3 0f 1e fa          	endbr64 
    149f:	55                   	push   %rbp
```

### 3 OpenMP

普通for循环: 0.0994856s

OpenMP: 0.0384518s
```sh
[3-SIMD-openMP]Starting comparison...
Arrays are equal (normal comparison).
normal comparison time: 0.0994856 seconds
Arrays are equal (OpenMP comparison).
OpenMP comparison time: 0.0384518 seconds
```
相关反汇编调用举例:
```
0000000000001690 <_Z21compare_arrays_openmpPKiS0_m._omp_fn.0>:
    1690:	f3 0f 1e fa          	endbr64 
    1694:	41 56                	push   %r14
```

### 4 TBB

普通for循环: 0.0991927s

TBB: 0.0185034s
```sh
[4-SIMD-TBB]Starting comparison...
Arrays are equal.
Arrays are equal (normal comparison).
Normal comparison time: 0.0991927 seconds
Arrays are equal (TBB comparison).
TBB comparison time: 0.0185034 seconds
-------------------------------
```

相关反汇编调用举例:
```
0000000000003100 <_ZN3tbb6detail2d19start_forINS1_13blocked_rangeImEEZ18compare_arrays_tbbPKiS6_mEUlRKS4_E_KNS1_16auto_partitionerEE6cancelERNS1_14execution_dataE>:
    3100:	f3 0f 1e fa          	endbr64 
    3104:	41 55                	push   %r13
```