Hello,
I'm doing performance experiments of my applications on UltraSparc T1.
In order to test the data of cache miss or other things, I'm in need
of some ways to access PIC and PCR. I wrote a simple module to read
and set these registers using the macros found in
asm-sparc64/system.h. However, no matter what I set to the pcr,
read_pcr and read_pic (I understand this should be 0 when pcr is 0)
always return 0.
After that, I found a system call (sys_perfctr) that would do this. So
in my program, I invoked this system call as below. (I also tried bind
the thread to a specific processor using setaffinity) However, I've
got the same problem. The output is below the program.
Could anyone teach me this? Sorry for this naive question. Thanks a lot!
btw, Linux kernel 2.6.20, gcc 4.2.1
#include <linux/unistd.h>
#include <syscall.h>
#include <errno.h>
#include <stdio.h>
#include <asm-sparc64/perfctr.h>
int main(void)
{
int opcode;
unsigned long arg0,arg1,arg2;
int error;
unsigned long pcr;
if(error=syscall(SYS_perfctr,PERFCTR_ON,0,0,0))
printf("error is %d\n",error);
if(error=syscall(SYS_perfctr,PERFCTR_SETPCR,0x04,0,0))
printf("error is %d\n",error);
if(error=syscall(SYS_perfctr,PERFCTR_GETPCR,&pcr,0,0))
printf("error is %d and %s\n",error,strerror(error));
printf("pcr is %d\n",pcr);
return(0);
}
output:
$gcc tryperfctr.c
$./a.out
error is -1
error is -1 and Unknown error 18446744073709551615
pcr is 0
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