[ntp:questions] FreeBSD recipe to setup for timekeeping

unruh unruh at invalid.ca
Tue Dec 10 22:05:13 UTC 2013


On 2013-12-10, Hal Murray <hal-usenet at ip-64-139-1-69.sjc.megapath.net> wrote:
> Does anybody have a URL for a page that describes how to setup a FreeBSD
> system for timekeeping?

Use either chrony or ntpd. 

>
> I've got a FreeBSD 9.1 system running on a 1.86 GHz Intel Atom chip.  It
> reports TSC-low is running at 14.584185 MHz and uses it for timekeeping.
>
> I googled for a while, but didn't find what I was looking for.  I think

You have not told us what you are looking for either. 

> it's tangled up with slowing down or stopping the CPU clock to save power.
> I'm looking for a page that says do XXX to save power or do XXX to get a

Do NOT use TSC for timekeeping then. You need a clock (eg I believe hpet
for example) that does not slow down. TSC counts cpu cycles. 

> better clock, where XXX are probably sysctl settings.
> kern.timecounter.choice: TSC-low(1000) ACPI-safe(850) i8254(0) HPET(950) dummy(-1000000)
>
>
> FreeBSD 8.0-RC1 running on a 2.8 GHz Celeron is using HPET.  TSC (non low)
> runs at 2793.170237 MHz.
> kern.timecounter.choice: TSC(800) HPET(900) ACPI-safe(850) i8254(0) dummy(-1000000)
> I haven't figured out why it things HPET is better than TSC.
>
Because it does not change when the cpu goes into power conservation?




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