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timeout(9r)
NAME
  timeout - General: Initializes a callout queue element

SYNOPSIS
  void timeout(
	  int (*function) (),
	  caddr_t argument,
	  register int time );

ARGUMENTS
  function
      Specifies a pointer to the routine to be called.

  argument
      Specifies a single argument to be passed to the called routine.

  time
      Specifies the amount of time to delay before calling the specified
      routine. You express time as time (in seconds) * hz.

DESCRIPTION
  The timeout routine initializes a callout queue element to make it easy to
  execute the specified routine at the time specified in the time argument.
  You often use callout routines for infrequent polling or error handling.
  The routine you specify will be called on the interrupt stack (not in
  processor context) as dispatched from the softclock routine.

  The global variable hz contains the number of clock ticks per second. This
  variable is a second's worth of clock ticks.

  Thus, if you wanted a 4-minute timeout, you would pass 4 * 60 * hz as the
  third argument to the timeout routine as follows:

	/* A 4-minute timeout */
	.
	.
	.
	timeout(lptout, (caddr_t)dev, 4 * 60 * hz);

NOTES
  The granularity of the time delay is dependent on the hardware. For
  example, the granularity of some Alpha CPUs is 1024 clock ticks per second.
  Other Alpha CPUs have a granularity of 1200 clock ticks per second. Still
  other Alpha CPUs exhibit a granularity of 128 clock ticks per second.
  Because the granularity of the time delay is dependent on the hardware, the
  operating system provides the hz and lbolt global variables. Use the hz
  global variable to determine the number of clock ticks per second for a
  specific Alpha CPU. Use the lbolt global variable as a periodic wakeup
  mechanism.

RETURN VALUES
  None

SEE ALSO
  Routines: untimeout(9r)

Index for Section 9r

Alphabetical listing for T

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