From: Stathis Kamperis <beket@dragonflybsd.org>
Date: Sat, 2 May 2009 11:23:25 +0000 (+0000)
Subject: clocks.7: Mention HPET cpu timer.
X-Git-Tag: v2.3.1~28
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/3005db81b962e8881b66bcf4edb62ec51409d12d

clocks.7: Mention HPET cpu timer.

Based on the commit message of bea6e27816f976132ff7ad7446c0e90406378f9b.
Also, replace .Sy macros with .Va when refering to sysctl variables.

Discussed-with: sephe@
Reviewed-by: swildner@
---

diff --git a/share/man/man7/clocks.7 b/share/man/man7/clocks.7
index 9157487b06..5f87360fc7 100644
--- a/share/man/man7/clocks.7
+++ b/share/man/man7/clocks.7
@@ -28,7 +28,7 @@
 .\" $FreeBSD: src/share/man/man7/clocks.7,v 1.9.2.5 2001/12/17 11:30:15 ru Exp $
 .\" $DragonFly: src/share/man/man7/clocks.7,v 1.3 2004/03/11 12:28:56 hmp Exp $
 .\" "
-.Dd May 1, 2009
+.Dd May 2, 2009
 .Os
 .Dt CLOCKS 7
 .Sh NAME
@@ -130,11 +130,25 @@ The TSC clock (64-bit register) on fifth-generation or later x86 systems.
 This is a real clock with a frequency that is equivalent to the number of
 cycles per second of the CPU(s).
 Its frequency can be found using the sysctl
-.Sy hw.tsc_frequency
+.Va hw.tsc_frequency
 and its presence via
-.Sy hw.tsc_present.
+.Va hw.tsc_present .
 It is used to interpolate between values of the scheduling clock.
 It is only available to applications in a purely machine-dependent manner.
+.It
+The HPET (High Precision Event Timers).
+Only main counter is used currently.
+This CPU timer is expected to be faster than ACPI-fast24 and ACPI-safe,
+so it should be given higher priority.
+HPET is not enabled by default.
+To enable it, you should add
+.Li debug.acpi.enabled="hpet"
+to your
+.Pa /boot/loader.conf .
+If the HPET is detected and attached,
+.Va kern.cputimer.name
+will report
+.Li HPET .
 .El
 .Pp
 Summary: if
@@ -148,7 +162,8 @@ isn't 1000000 then the application is probably using the wrong clock.
 .Xr select 2 ,
 .Xr clock 3 ,
 .Xr moncontrol 3 ,
-.Xr times 3
+.Xr times 3 ,
+.Xr loader.conf 5
 .Sh AUTHORS
 .An -nosplit
 This man page has been written by