Re: 2.6.18 w/ GPS time source: worse performance

[Udo van den Heuvel <udovdh@xs4all.nl>]

Lee Revell wrote:
> On Wed, 2006-10-18 at 17:20 +0200, Udo van den Heuvel wrote:
>> Lee Revell wrote:
>>> On Tue, 2006-10-17 at 17:25 +0200, Udo van den Heuvel wrote:
>>>> Why does a GPS as time source (with ntpd) perform so much worse with 2.6.18?
>>> Um... you don't give nearly enough information to even begin to know
>>> what you're talking about.
>> No one here with a vague idea about the cause for the bad performance?
>> I am sure I not the only one experiencing this.
> 
> No, the issue is that a one-sentence bug report is not helpful.  You
> don't give enough information to debug it.  Kernel config, steps to
> reproduce, etc, etc.
> 
> Please look at LKML archives for some examples of the type of bug report
> that does get a response.

Get the latest kernel.
Compile for your system
Get ntpd.
Configure for your PPS/NMEA source.
Run ntpd.
Watch performance.
Repeat watching of performance.

It is not a crash. Not an oops.
It is stuff that is visible by watching ntpq -pn output, by letting mrtg
graph stuff, etc. Watch the offset and jitter collumns.
Check /usr/sbin/ntpdc -c kerninfo output. Graph that stuff.
Over the monhts you see changes. Some of them you can explain. Some you
can't.

I can understand this is not you everyday bug but this *is* an issue.