NAME

       get_cyclecount — get the CPU's fast counter register contents

SYNOPSIS

       #include <sys/param.h>
       #include <sys/systm.h>
       #include <machine/cpu.h>

       uint64_t
       get_cyclecount(void);

DESCRIPTION

       The  get_cyclecount()  function  uses  a register available in most modern CPUs to return a value that is
       monotonically increasing inside each CPU.

       On SMP systems, there will be a number of separate monotonic sequences, one for each  CPU  running.   The
       value  in  the  SMP case is selected from one of these sequences, dependent on which CPU was scheduled to
       service the request.

       The speed and the maximum value of each counter is CPU-dependent.  Some CPUs (such as the Intel 80486) do
       not have such a register, so get_cyclecount() on these platforms returns  a  (monotonic)  combination  of
       numbers represented by the structure returned by binuptime(9).

       The AMD64 and Intel 64 processors use the TSC register.

SEE ALSO

       binuptime(9)

HISTORY

       The get_cyclecount() function first appeared in FreeBSD 5.0.

AUTHORS

       This manual page was written by Mark Murray <markm@FreeBSD.org>.

Debian                                           March 15, 2011                                GET_CYCLECOUNT(9)