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| GET_CYCLECOUNT(9) | FreeBSD Kernel Developer's Manual | GET_CYCLECOUNT(9) |
NAME
get_cyclecount —
SYNOPSIS
#include <sys/param.h>
#include <sys/systm.h>
#include <machine/cpu.h>
uint64_t
get_cyclecount(void);
DESCRIPTION
Theget_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
Theget_cyclecount() function first appeared in
FreeBSD 5.0.
AUTHORS
This manual page was written by Mark Murray <markm@FreeBSD.org>.| March 15, 2011 | FreeBSD 13.1-RELEASE |
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