[ntp:hackers] NTP nanokernel as starting point?
Poul-Henning Kamp
phk at phk.freebsd.dk
Sun May 13 00:28:41 PDT 2007
In message <2729632a0705121557s6ca5d561n433cd3cb80124b5d at mail.gmail.com>, skill
zero at gmail.com writes:
>On 5/12/07, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
>
>> Building a PLL is a lot easier than people think:
>>
>> x = estimated_offset;
>> f = x * a + i;
>> i += x * b;
>> tell_kernel(f);
>>
>> The only tricky part is choosing a and b.
>
>I guess what confuses me is that it looks like this is what the
>hardupdate function does in the kernel clock discipline to update
>time_freq so I wasn't sure why I'd need to supply it to the kernel.
you don't have to give it a frequency adjustment, you can stick
with a phase adjustment.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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