Xeon Phi 《协处理器高性能编程指南》随书代码整理 part 4

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <math.h>
 4 
 5 #define S       1024*32
 6 #define T       float
 7 #define ITER    1000
 8 #define VLEN    16
 9 
10 __declspec(noinline) void scalar(T *A, T *B, T *C, T k)     // 标量型
11 {
12     __assume_aligned(A, 64);                // 声明数组对齐到 512 bit
13     __assume_aligned(B, 64);
14     __assume_aligned(C, 64);
15     for (int i = 0; i < S; i++)
16     {
17         T tmp = A[i] * k + B[i];
18         if (tmp > 0.5f)
19             tmp *= sin(B[i]);
20         C[i] = tmp;
21     }   
22 }
23 
24 __declspec(noinline) void shortVector(T *A, T *B, T *C, T k)// 短向量型
25 {
26     __assume_aligned(A, 64);
27     __assume_aligned(B, 64);
28     __assume_aligned(C, 64);
29     for (int i = 0; i < S; i+=VLEN)
30     {
31         T tmp[VLEN];
32         tmp[:]= A[i:VLEN] * k + B[i:VLEN];  // Cilk 的 tmp[起点:长度] 作引用
33         if (tmp[:] > 0.5f)
34             tmp[:] *= sin(B[i:VLEN]);
35         C[i:VLEN] = tmp[:];
36     }
37 }
38 
39 int main()
40 {
41     volatile __int64 start, time1, time2;
42     T ref_result, short_result;    
43     const float k = 0.5;
44     
45     T *A, *B, *C;                                   // 声明并定义对齐的数组或数组指针
46     posix_memalign((void **)&A, 64, sizeof(T)*S);
47     posix_memalign((void **)&B, 64, sizeof(T)*S);
48     posix_memalign((void **)&C, 64, sizeof(T)*S);
49     //__declspec(align(64)) T A[S], B[S], C[S];     // 等价的声明方式
50         
51     A[0:S] = __sec_implicit_index(0);               // 数组赋值为 {0, 1, 2, ...}
52     B[0:S] = __sec_implicit_index(0);
53     C[0:S] = 0;
54     //for(int i=0;i<S;i++)                          // 等价的复制方法
55     //   A[i] = B[i] = i, C[i] = 0;
56 
57     //for(int i=0;i<10;i++)
58     //    printf("%f, ", A[i]);
59     //printf("
");
60     //for(int i=0;i<10;i++)
61     //    printf("%f, ", B[i]);
62     //printf("
");
63     
64     start = __rdtsc();                              // 计时器，计算 CPU 的tick 数
65     for (int i = 0; i < ITER; i++)    
66         scalar(A, B, C, k);
67     time1 = __rdtsc() - start;
68     //for(int i=0;i<10;i++)
69     //    printf("%f, ", C[i]);
70     //printf("
");    
71     ref_result = __sec_reduce_add(C[0:S]);          // 规约加，用于比较结果是否正确
72 
73     start = __rdtsc();
74     for (int i = 0; i < ITER; i++)       
75         shortVector(A, B, C, k);       
76     time2 = __rdtsc() - start;
77     //for(int i=0;i<10;i++)
78     //    printf("%f, ", C[i]);
79     //printf("
");
80     short_result = __sec_reduce_add(C[0:S]);
81     
82     printf("ref:	%f, %Id CPU tick
short:	%f, %Id CPU tick
", ref_result, time1, short_result, time2);
83     return 0;
84 }

[cuan@server3145 XeonPhi]$ icc kk.c -O0
[cuan@server3145 XeonPhi]$ ./a.out 
ref:      -39578.562500, 1514650782 CPU tick
short:    -39578.562500, 1802072334 CPU tick
[cuan@server3145 XeonPhi]$ icc -mmic kk.c -O0
[cuan@server3145 XeonPhi]$ scp a.out cuan@mic0:/home/cuan
cuan@mic0's password: 
a.out                                                       100%   33KB  33.5KB/s   00:00    
[cuan@server3145 XeonPhi]$ ssh cuan@mic0
cuan@mic0's password: 
[cuan@server3145-mic0 ~]$ ./a.out
ref:      -39578.562500, 1467023211 CPU tick
short:    -39578.562500, 414319544 CPU tick

[cuan@server3145 XeonPhi]$ icc kk.c -O3
[cuan@server3145 XeonPhi]$ ./a.out
ref:      -39578.617188, 387034332 CPU tick
short:    -39578.617188, 395228084 CPU tick
[cuan@server3145 XeonPhi]$ icc -mmic kk.c -O3
[cuan@server3145 XeonPhi]$ scp a.out cuan@mic0:/home/cuan
cuan@mic0's password: 
a.out                                                       100%   90KB  90.2KB/s   00:00    
[cuan@server3145 XeonPhi]$ ssh cuan@mic0
cuan@mic0's password: 
[cuan@server3145-mic0 ~]$ ./a.out
ref:      -39578.429688, 638000619 CPU tick
short:    -39578.429688, 633708861 CPU tick