software interruption

Hello,

I'm trying to figure out what kind of situation would make the software
interruption to take a good portion of CPU time. I can see "si" on top
output, but I can never manage to get it higher than 0.3% or so. I even
wrote a code like this:

L1: movl $400, %eax
int $0x80
jmp L1

My goal was to call an invalid system call in order to spend the most
time on software interrupt. Originally I had the C code

int main(void) { while(1) syscall(400); }

but then I addapted into that assembly code. I really can't figure out
a way to make that number to get higher. How can I get near to 100%si?
And, if that's not possible, what's the use of having it on top?

[]'s
Rafael
.

Relevant Pages