ATTIMER(4) BSD Kernel Interfaces Manual ATTIMER(4)NAME
attimer -- i8254 Programmable Interval Timer (AT Timer) driver
SYNOPSIS
This driver is a mandatory part of x86 kernels.
The following tunables are settable from the loader(8):
hint.attimer.X.clock
controls support for the event timer functionality. Setting this value to 0 disables it. The default value is 1.
hint.attimer.X.timecounter
controls support for the time counter functionality. Setting this value to 0 disables it. The default value is 1.
hw.i8254.freq
allows overriding the default counter frequency. The same value is also available at run-time via the machdep.i8254_freq sysctl.
DESCRIPTION
This driver uses i8254 Programmable Interval Timer (AT Timer) hardware to supply the kernel with one timecounter and one event timer, and to
generate sound tones for the system speaker. This hardware includes three channels. Each channel includes a 16 bit counter which decreases
with a known, platform-dependent frequency. Counters can operate in several different modes, including periodic and one-shot. The output of
each channel has platform-defined wiring: one channel is wired to the interrupt controller and may be used as event timer, one channel is
wired to the speaker and used to generate sound tones, and one timer is reserved for platform purposes.
The attimer driver uses a single hardware channel to provide both time counter and event timer functionality. To make this possible, the
respective counter must be running in periodic mode. As a result, the one-shot event timer mode is supported only when time counter func-
tionality is disabled.
The event timer provided by the driver is irrelevant to CPU power states.
SEE ALSO apic(4), atrtc(4), eventtimers(4), hpet(4), timecounters(4)BSD May 26, 2014 BSD
Check Out this Related Man Page
APIC(4) BSD Kernel Interfaces Manual APIC(4)NAME
apic -- Advanced Programmable Interrupt Controller (APIC) driver
SYNOPSIS
This driver is a mandatory part of amd64 kernel. To compile this driver into i386 or pc98 kernel, place the following line in your kernel
configuration file:
device apic
The following tunable is settable from the loader(8):
hint.apic.X.clock
controls event timers functionality support. Setting to 0, disables it. Default value is 1.
hint.apic.X.disabled
Set this to 1 to disable APIC support, falling back to the legacy PIC.
DESCRIPTION
There are two components in the Intel APIC system, the local APIC (LAPIC) and the I/O APIC. There is one local APIC in each CPU in the sys-
tem. There is typically one I/O APIC for each peripheral bus in the system.
Local APICs manage all external interrupts for a specific processor. In addition, they are able to accept and generate inter-processor
interrupts (IPIs).
I/O APICs contain a redirection table, which is used to route the interrupts they receive from peripheral buses to one or more local APICs.
Each local APIC includes one 32-bit programmable timer. This driver uses them to supply kernel with one event timer named "LAPIC". Event
timer provided by the driver supports both one-shot an periodic modes. Because of local APIC nature it is per-CPU. The timer frequency is
not reported by the platform and so automatically measured by the driver on the first use. Depending on CPU model this timer may stop in C3
and deeper CPU sleep states. Driver automatically adjusts event timer priority and reports it to prevent entering dangerous sleep states
when it is used.
SEE ALSO atrtc(4), attimer(4), eventtimers(4), hpet(4)BSD December 20, 2011 BSD
hello all
since a process running in kernel mode cannnot be preempted by any other process what would be the status of Timer interrupt that occurs when the time quantum of a process is elapsed?
thanks (2 Replies)
Hello:
Executing following script i'm getting error:
1=1+1: 0403-058 Assignment requires an lvalue.
It's not assuming the counter but i don't know why.
Some hint?
Thank you very much in advance.
#!/bin/ksh
<path>/tiempos.txt
num_exe=1
TIEMPOS=<path>/tiempos.txt
while ]
do (2 Replies)
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How do you set timer as output to the command line so that you get an output like
Has been waiting for 5 seconds
Has been waiting for 6 seconds
...
Where only the number changes. (2 Replies)
Hi Experts,
I am in need for some help. My competence level on unix is not at all helping me to resolve this. Please help.
My Input for a system command is as under:
Counters are getting pegged each hour. I need to have a difference printed rather than pegged counter values.
Counter... (2 Replies)
Hello. I am pretty new to unix and shell scripting and I was wondering if there might be a way to banner a countdown timer inside a script. We currently have an existing script that does a 2 minute sleep but thought it might be fun to actually make it banner a countdown timer until it is finished.... (3 Replies)