From: "John Zhou" <zjzhou@newrocktech.com>
To: "'linuxppc-embedded'" <linuxppc-embedded@lists.linuxppc.org>
Subject: question on PPC performance
Date: Fri, 30 Jan 2004 18:22:24 +0800 [thread overview]
Message-ID: <000001c3e71a$f4d68010$b702a8c0@newrock2> (raw)
In-Reply-To: <001b01c3e70d$3654e3f0$0100a8c0@pc002>
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);
}
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2004-01-30 10:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200401300952.AA178585798@actinium.org>
2004-01-30 8:43 ` Problem in Cross compiling Pwlib for LINUX Ale ppc
2004-01-30 10:22 ` John Zhou [this message]
2004-01-30 11:32 ` question on PPC performance John Zhou
2004-01-30 13:33 VanBaren, Gerald (AGRE)
2004-02-02 5:17 ` John Zhou
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