RISCV-V扩展执行速度测试

测试函数

测试函数为riscv-v1.0扩展官方文档

void saxpy_c(size_t n, const float a, const float *x, float *y)
{
        size_t i;
        for (i = 0; i < n; i++)
        {
                y[i] = a * x[i] + y[i];
        }
}

用汇编（v扩展）实现该函数saxpy.s

.global saxpy
saxpy:
        vsetvli a4, a0, e32, m8,ta,ma
        vle32.v v0, (a1)
        sub a0, a0, a4
        slli a4, a4, 2
        add a1, a1, a4
        vle32.v v8, (a2)
        vfmacc.vf v8, fa0, v0
        vse32.v v8, (a2)
        add a2, a2, a4
        bnez a0, saxpy
        ret

主函数

1. 普通实现

   #include <stddef.h>
   #include <stdio.h>
   #include <time.h>
   
   void saxpy_c(size_t n, const float a, const float *x, float *y)
   {
           size_t i;
           for (i = 0; i < n; i++)
           {
                   y[i] = a * x[i] + y[i];
           }
   }
   
   int main()
   {
           size_t size = 1000;
           const float a = 1.0;
           int loop = 1000;
           float array1[size];
           float array2[size];
   
           for (int i = 0; i < size; i++)
           {
                   array1[i] = i + 1;
                   array2[i] = i + 1;
           }
   
           clock_t start, end;
           double duration;
   
           start = clock();
           for (int i = 0; i < loop; i++)
                   saxpy_c(size, a, array1, array2);
           end = clock();
   
           printf("size: %d\n", size);
           printf("loop: %d\n", loop);
           printf("time: %dms\n", end - start);
   
           return 0;
   }
   

   分别使用x86的编译器和risc-v的编译器编译并执行，测试执行时间

   1. x86

   gcc callsaxpy.c -o test_x86
   

   ./test_x86
   

   

   2. riscv

   riscv64-unknown-elf-gcc callsaxpy.c -o test_rv
   

   spike --isa=RV64GCV pk test_rv
   

   

2. riscv-v扩展实现

   #include <stddef.h>
   #include <stdio.h>
   #include <time.h>
   
   extern void saxpy(size_t n, const float a, const float *x, float *y);
   
   int main()
   {
   	size_t size = 1000;
   	const float a = 1.0;
   	int loop = 1000;
   	float array1[size];
   	float array2[size];
   
   	clock_t start, end;
   
   	for (int i = 0; i < size; i++)
   	{
   		array1[i] = i + 1;
   		array2[i] = i + 1;
   	}
   
   	//调用saxpy函数
   	start = clock();
   	for (int i = 0; i < loop; i++)
   		saxpy(size, a, array1, array2);
   	end = clock();
   
   	printf("size: %d\n", size);
   	printf("loop: %d\n", loop);
   	printf("time: %dms\n", end - start);
   
   	return 0;
   }
   

   spike --isa=RV64GCV pk test_rv_v
   

   

   aa.png

深度测试

分别对不同数据量（10、100、1000）进行测试，为突出效果，每次循环1000遍。

	size=10	size=100	size=1000
x86	23ms	203ms	2052ms
RISCV	270ms	2430ms	24030ms
RISCV-V	24ms	54ms	334ms