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Kernel Functions for Driversdrv_hztousec(9F)


NAME

 drv_hztousec - convert clock ticks to microseconds

SYNOPSIS

 
#include <sys/types.h>
#include <sys/ddi.h>
clock_t drv_hztousec(clock_t hertz);

INTERFACE LEVEL

 

Architecture independent level 1 (DDI/DKI).

PARAMETERS

 
hertz
The number of clock ticks to convert.

DESCRIPTION

 

drv_hztousec() converts into microseconds the time expressed by hertz, which is in system clock ticks.

The kernel variable lbolt, whose value should be retrieved by calling ddi_get_lbolt(9F), is the length of time the system has been up since boot and is expressed in clock ticks. Drivers often use the value of lbolt before and after an I/O request to measure the amount of time it took the device to process the request. drv_hztousec() can be used by the driver to convert the reading from clock ticks to a known unit of time.

RETURN VALUES

 

The number of microseconds equivalent to the hertz parameter. No error value is returned. If the microsecond equivalent to hertz is too large to be represented as a clock_t , then the maximum clock_t value will be returned.

CONTEXT

 

drv_hztousec() can be called from user or interrupt context.

SEE ALSO

 

ddi_get_lbolt(9F), drv_usectohz(9F), drv_usecwait(9F)

Writing Device Drivers


SunOS 5.9Go To TopLast Changed 12 Nov 1992

 
      
      
Copyright 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.