How to get RTC tick under user mode?

[frakie]

Hi 'body, is there any function to get the RTC ticks under user mode
on linux?
I could not use gettimeofday because it is too slow and affects
measures...

 

[Walter Roberson]

Hi 'body, is there any function to get the RTC ticks under user mode
on linux?
I could not use gettimeofday because it is too slow and affects
measures...

There is no way to do that using only the facilities provided
by the C language itself. You will need to use system-specific
extensions. Please consult a linux programming newsgroup (and it might
be in a linux programming FAQ somewhere.)

 

[Charlie Gordon]

There is no way to do that using only the facilities provided
by the C language itself. You will need to use system-specific
extensions. Please consult a linux programming newsgroup (and it might
be in a linux programming FAQ somewhere.)

Google for: RDTSC linux

 

[frakie]

Google for: RDTSC linux

Thanks this is really useful!


extern __inline__ unsigned long long int rdtsc()
{
long long int x;
__asm__ volatile (".byte 0x0f, 0x31" : "=A" (x));
return x;
}

By now I have to find a divisor to transform it in microseconds..