Manual Pages for UNIX Operating System command usage for man drv_hztousec

Kernel Functions for Drivers                     drv_hztousec(9F)



NAME
     drv_hztousec - convert clock ticks to microseconds

SYNOPSIS
     #include 
     #include 

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


     The length of time the system has been up since boot can  be
     retrieved  by calling ddi_get_lbolt(9F), which will return a
     value of type clock_t containing the number of  clock  ticks
     since  boot. 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. The drv_hztousec() func-
     tion 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  parame-
     ter.   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
     The drv_hztousec() function can be called from user,  inter-
     rupt, or kernel context.

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


     Writing Device Drivers









SunOS 5.11           Last change: 4 Sep 2009                    1