Hi Eric,
eric johnson wrote:
i need to write a user land program which would measure the times in milliseconds . how do i do this ? i wouldnt want to make a system call.
If you seriously want to prevent system calls you have three options:
- Use the time stamp counter of your machine (if it has one, you didn't specify your hardware). Usual problems are, frequency stability of you do dynamic frequency scaling and synchronicity on MP. TSC has a very low overhead.
- Your program could be allowed hardware access to a timer device, such as the HPET and drive it.
- You have an external clock server which provides the current time in a shared memory page. This could be a userland program or the kernel. In both cases, the timer interrupt would have to be at least 1kHz for you required resolution.
Cheers, Martin