schedule()

[Richard B. Johnson]

I just read on this list that:

    while(something)
    {
      current->policy |= SCHED_YIELD;
      schedule();
    }

Will no longer be allowed in a kernel module! If this is true, how
do I loop, waiting for a bit in a port, without wasting CPU time?

A lot of hardware does not generate interrupts upon a condition,
there is no CPU activity that could send a wake_up_interruptible()
to something sleeping.

For instance, I need to write data to a hardware FIFO, one long-word
at a time, but I can't just write. I have to wait for a bit to be
set or reset for each and every write. I'm going to be burning a
lot of CPU cycles if I can't schedule() while the trickle-down-effect
of the hardware is happening.

Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (797.90 BogoMips).

        111,111,111 * 111,111,111 = 12,345,678,987,654,321