[ntp:questions] Linux NTP Kernel unsync flag remains long after NTP&Kernel have PPL sync

Unruh unruh-spam at physics.ubc.ca
Tue Sep 2 17:46:29 UTC 2008


Serge Bets <serge.bets at NOSPAM.laposte.invalid> writes:

>Hello Bill,

> On Saturday, August 30, 2008 at 16:54:47 +0000, Unruh wrote:

>> when hpet is enabled, all the interrupts from the rtc are hjacked and
>> never delivered to the system as rtc interrupts.

>Exact. The nice dreams above about the mythical RTC microsecond are
>totally annihilated by the HPET problem. Solutions today are only nohpet
>or --directisa. However it appears that, following your bug report,
>David Brownell is now exploring a new workaround for future kernels.
>IIUC he managed to convince ACPI to intercept RTC interrupts and to
>forward them to the CPU. I could not test the patch, and know nothing
>about ACPI. But this looks quite promising.


>> And yes, Mandriva uses the util-linux version

>So do the current and the (now frozen) future Debians, and so does
>Ubuntu. They also call hwclock --hctosys *twice* at startup (¿!¡?).
>They evaluate the drift rate from shutdown to shutdown, thus including
>uptime. And they don't correct drift at all.

>At the morning startup, those distros would give me an initial offset of
>maybe 5 plain seconds, instead of the 5 milliseconds or better I get
>routinely from hwclock 2.33


>> Why does Brian not get his version back into util-linux?

>To me, hwclock seems to be much better standalone than in a collection
>of unrelated utilities. Active development vs. careless stagnation.

I am certainly not suggesting careless stagnation. I would hope Brian would
continue to develop it. It is just that distros are used to util-linux, and
would have to strip out the hwclock in there and then install the
standalone. It would seem far more likely to get adopted if the hwclock in
the util-linux were the good one. 

Mind you idiocy on the part of the distributions is not unkown. Exactly the
same thing has happpened re cdrecord vs wodim. Wodim is a fork from an
ancient version of cdrecord, with minimal updates ( careless stagnation
describes it well) while cdrecord is under active development. But the
distros are almost all distributing the latter. 




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