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GET_CYCLECOUNT(9)	   Kernel Developer's Manual	     GET_CYCLECOUNT(9)

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>.

FreeBSD	13.2			March 15, 2011		     GET_CYCLECOUNT(9)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY | AUTHORS

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