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Re: [off topic] A pause in C?

In article <Pine.LNX.3.96.981007123258.2069A-100000@omnic.rumpus.net>,
Michael Beattie <mickyb@es.co.nz> wrote:
>I am after a way to generate a pause of 300ns in a C program I am working

In general, you cannot guarantee pauses in a multitasking system
like Unix or Linux. Pauses can be set in microseconds using usleep(),
but not in nanoseconds. And even then that is only the _minimum_ time
that call will sleep - if the system decides to run another process
at that point your program will only continue until the timeslice
of the other process is over, 10 ms later ..

>At the moment, I am using a for loop of about 700000 iterations..
>works okay, but on a faster system it will die.. (needed to slow down I/O
>with an interface card)

If you need to do timing that strict, and you're talking to hardware,
you shouldn't do it from userspace but write a kernel module instead.

Or you could use Linux-RT (Real Time), but the real time programs you
have to create for Linux-RT are essentially kernel modules too ..

  "Did I ever tell you about the illusion of free will?"
    -- Sheriff Lucas Buck, ultimate BOFH.

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