CCS/AM5716: IPU Unicache prefetch issue

Part Number: AM5716

Tool/software: Code Composer Studio

Hello,

I am trying the Prefech of UNICACHE.  After enabling CACHE_OCP[4]Prefetch, however, it spends around 1200 more CPU cycles (2100 -> 3300). I suppose that the Prefetch doesn't help but increases the bus traffic!? Do I misuse Prefetch? Can you provide a experiment to help me test Prefetch of UNICACHE?

The following is my pseudo code. 

#define SIZE (65536)     // 64*1024
#define STRIDE (32)     // 256/8

char a[SIZE];

j = a[STRIDE*0];
j = a[STRIDE*1];
j = a[STRIDE*2];
j = a[STRIDE*3];
j = a[STRIDE*4];
j = a[STRIDE*5];
j = a[STRIDE*6];
j = a[STRIDE*7];
j = a[STRIDE*8];
j = a[STRIDE*9];
j = a[STRIDE*10];
j = a[STRIDE*11];
j = a[STRIDE*12];
j = a[STRIDE*13];
j = a[STRIDE*14];
j = a[STRIDE*15];

Regards,

Hungwei