Dear all,
I have an question on PPC performance:
I have linux running based on mpc8250 with 200/166/66 clock configuration. But,
I found that every CPU instruction used about 5 ns when accessing SDRAM,
otherwise, every CPU instruction used about 15 ns when accessing other devices
such as port A/B/C/D, immr, etc, except accessing SDRAM.
Thanks any help!
John
=================================================
The function I used is:
void performance_test(void)
{
unsigned long i, d1, d2;
static unsigned long kkk;
unsigned short time;
volatile unsigned long* portC = (
volatile unsigned long*)0xF0010D50;
volatile unsigned long * tmp = &kkk;
*(volatile unsigned char*)0xF0010D80 &=
~0xB0;
*(volatile unsigned short*)0xF0010D92 =
0x0002;
*(volatile unsigned char*)0xF0010D80 |=
0x10;
*(volatile unsigned long*)0xF0010D44 &=
~0x00000002;
d1 = *(volatile unsigned
long*)0xF0010D50;
d1 &= ~0x00000003;
d2 = d1 | 0x00000002;
d1 |= 0x00000001;
*(volatile unsigned short*)0xF0010D9E =
0;
for (i=0; i<1000; i++)
{
*portC = d1;
*portC = d2;
}
time = *(volatile unsigned
short*)0xF0010D9E;
printk ("#test2: 2 access loop 1000
times use %dns\r\n", time*15);
*(volatile unsigned short*)0xF0010D9E =
0;
for (i=0; i<1000; i++)
{
*tmp = d1;
*tmp = d2;
}
time = *(volatile unsigned
short*)0xF0010D9E;
printk ("#test3: 2 access loop 1000
times use %dns\r\n", time*15);
}
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