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Some formatting fixes.

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Submitted by:	ru
This commit is contained in:
Alexander Motin 2011-12-16 14:19:46 +00:00
parent 92ed4e1a24
commit 9c121fecc2
1 changed files with 31 additions and 14 deletions
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45
share/man/man4/eventtimers.4
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@ -46,16 +46,22 @@ statistics, time keeping, profiling and many other things, based on
.Xr callout 9
mechanism.
These purposes now grouped into three main callbacks:
.Bl -tag
.It hardclock()
.Bl -tag -width ".Fn hardclock"
.It Fn hardclock
.Xr callout 9
and timekeeping events entry. Called with frequency defined by hz variable,
and timekeeping events entry.
Called with frequency defined by
.Va hz
variable,
usually 1000Hz.
.It statclock()
statistics and scheduler events entry. Called with frequency about 128Hz.
.It profclock()
profiler events entry. When enabled, called with frequency about 8KHz.
.It Fn statclock
statistics and scheduler events entry.
Called with frequency about 128Hz.
.It Fn profclock
profiler events entry.
When enabled, called with frequency about 8KHz.
.El
.Pp
Different platforms provide different kinds of timer hardware.
The goal of the event timers subsystem is to provide unified way to control
that hardware, and to use it, supplying kernel with all required time-based
@ -80,11 +86,13 @@ kern.eventtimer.et.HPET.flags: 7
kern.eventtimer.et.HPET.frequency: 14318180
kern.eventtimer.et.HPET.quality: 550
.Ed
, where:
.Bl -tag
.Pp
where:
.Bl -inset
.It Va kern.eventtimer.et. Ns Ar X Ns Va .flags
is a
bitmask, defining event timer capabilities:
.Bl -tag -compact
.Bl -tag -offset indent -width indent -compact
.It 1
periodic mode supported,
.It 2
@ -97,8 +105,10 @@ timer may stop when CPU goes to sleep state,
timer supports only power-of-2 divisors.
.El
.It Va kern.eventtimer.et. Ns Ar X Ns Va .frequency
is a
timer base frequency,
.It Va kern.eventtimer.et. Ns Ar X Ns Va .quality
is an
integral value, defining how good is this timer, comparing to others.
.El
.Pp
@ -107,7 +117,7 @@ Current choice can be read and affected via
.Va kern.eventtimer.timer
tunable/sysctl.
Several other tunables/sysctls are affecting how exactly this timer is used:
.Bl -tag
.Bl -inset
.It Va kern.eventtimer.periodic
allows to choose periodic and one-shot operation mode.
In periodic mode, periodic interrupts from timer hardware are taken as the
@ -119,15 +129,22 @@ Default value depends of chosen timer capabilities, but one-shot mode is
preferred, until other is forced by user or hardware.
.It Va kern.eventtimer.singlemul
in periodic mode specifies how much times higher timer frequency should be,
to not strictly alias hardclock() and statclock() events. Default values are
to not strictly alias
.Fn hardclock
and
.Fn statclock
events.
Default values are
1, 2 or 4, depending on configured HZ value.
.It Va kern.eventtimer.idletick
makes each CPU to receive every timer interrupt independently of whether they
busy or not. By default this options is disabled. If chosen timer is per-CPU
busy or not.
By default this options is disabled.
If chosen timer is per-CPU
and runs in periodic mode, this option has no effect - all interrupts are
always generating.
.El
.Sh SEE ALSO
.Xr attimer 4 ,
.Xr atrtc 4 ,
.Xr attimer 4 ,
.Xr hpet 4