[ILUG] Measuring time

[Martin Donlon]

This should do the trink in gcc:

#include <linux/types.h>

inline void read_tsc(u_int64_t *tsc){
    __asm__ __volatile__(
        "rdtsc\n\t"
        : "=A" (*tsc)
    );
}


Though my gcc inline asm syntax is a bit rusty.

On Thu, May 24, 2001 at 08:08:11PM +0100, Paul Kelly wrote:
> Anthony Harrington wrote:
> 
> > Can anyone tell me a system call for measuring time in nano-seconds ?
> 
> 
> I don't believe there is one. The overhead of a syscall will affect your 
> timing anyway. Your best bet is probably the TSC - a CPU register on 
> i586 class CPUs. It's a counter increments every clock cycle, so the 
> resolution - and the answer you get from it - depends on the clock speed 
> of the CPU. Have a look in the source of UAE for an example of how to 
> use it.
> 
> Not what you'd call portable, but it gets the job done.
> 
> Paul.
> 
> 
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-- 
Martin
--
Bother! cried Pooh, as he sold Eeyore to the glue factory.