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freebsd-dev/share/man/man9/get_cyclecount.9

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Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
.\" Copyright (c) 2000 Mark R V Murray
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
mdoc(7) police: tidy up the markup. This manpage should be repo-copied to get_cyclecount.9.
2002-01-10 10:48:39 +00:00
.\" $FreeBSD$
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
.\"
.Dd November 20, 2000
mdoc(7) police: tidy up the markup. This manpage should be repo-copied to get_cyclecount.9.
2002-01-10 10:48:39 +00:00
.Dt GET_CYCLECOUNT 9
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
.Os
.Sh NAME
Removed <sys/queue.h> from the list of required include files and corrected the name of the function (get_cyclecount()). Requested by: bde
2002-01-06 23:56:12 +00:00
.Nm get_cyclecount
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
.Nd get the CPU's fast counter register contents
.Sh SYNOPSIS
mdoc(7) police: Use the new .In macro for #include statements.
2001-10-01 16:09:29 +00:00
.In sys/param.h
Fix required includes in accordance with recent source fixes. Submitted by: bde
2002-03-01 18:43:15 +00:00
.In sys/systm.h
mdoc(7) police: Use the new .In macro for #include statements.
2001-10-01 16:09:29 +00:00
.In machine/cpu.h
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
.Ft u_int64_t
Removed <sys/queue.h> from the list of required include files and corrected the name of the function (get_cyclecount()). Requested by: bde
2002-01-06 23:56:12 +00:00
.Fn get_cyclecount "void"
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
.Sh DESCRIPTION
The
Removed <sys/queue.h> from the list of required include files and corrected the name of the function (get_cyclecount()). Requested by: bde
2002-01-06 23:56:12 +00:00
.Fn get_cyclecount
mdoc(7) police: tidy up the markup. This manpage should be repo-copied to get_cyclecount.9.
2002-01-10 10:48:39 +00:00
function uses a register
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
available in most modern CPUs
to return a value
that is monotonically increasing
inside each CPU.
.Pp
mdoc(7) police: tidy up the markup. This manpage should be repo-copied to get_cyclecount.9.
2002-01-10 10:48:39 +00:00
On SMP systems,
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
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.
.Pp
mdoc(7) police: tidy up the markup. This manpage should be repo-copied to get_cyclecount.9.
2002-01-10 10:48:39 +00:00
The speed and the maximum value
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
of each counter
Fixed typos: dependant -> dependent
2001-05-01 14:10:12 +00:00
is CPU-dependent.
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
Some CPUs
(such as the
.Tn Intel
80386 and 80486)
do not have such a register,
so
Removed <sys/queue.h> from the list of required include files and corrected the name of the function (get_cyclecount()). Requested by: bde
2002-01-06 23:56:12 +00:00
.Fn get_cyclecount
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
on these platforms
returns the number of nanoseconds
represented by the
structure returned by
.Xr nanotime 9 .
.Pp
The
.Tn Pentium
processors all use the
.Li TSC
register.
.Pp
The
mdoc(7) police: minor cleanup.
2000-11-22 08:19:15 +00:00
.Tn Alpha
processors use the
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
.Li PCC
register.
.Pp
The
.Tn IA64
processors use the
.Li AR.ITC
register.
.Sh SEE ALSO
.Xr nanotime 9
.Sh HISTORY
The
Removed <sys/queue.h> from the list of required include files and corrected the name of the function (get_cyclecount()). Requested by: bde
2002-01-06 23:56:12 +00:00
.Fn get_cyclecount
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
function first appeared in
mdoc(7) police: minor cleanup.
2000-11-22 08:19:15 +00:00
.Fx 5.0 .
Add a consistent API to a feature that most modern CPUs have; a fast counter register in-CPU. This is to be used as a fast "timer", where linearity is more important than time, and multiple lines in the linearity caused by multiple CPUs in an SMP machine is not a problem. This adds no code whatsoever to the FreeBSD kernel until it is actually used, and then as a single-instruction inline routine (except for the 80386 and 80486 where it is some more inline code around nanotime(9). Reviewed by: bde, kris, jhb
2000-11-21 19:55:21 +00:00
.Sh AUTHORS
This manual page was written by
.An Mark Murray Aq markm@FreeBSD.org .
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