Messages in this thread | | | Subject | Re: [GIT pull] ntp updates for 2.6.31 | From | john stultz <> | Date | Tue, 23 Jun 2009 14:41:56 -0700 |
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On Tue, 2009-06-23 at 15:36 +0200, Ingo Molnar wrote: > The PPS patches i've seen just export IRQ timestamps to user-space. > > That is not very robust in my opinion when it comes to do time > approximations - to get quick, low-latency action and precise > measurements it's best to keep the critical path as short as > possible, and within a single source code repository: i.e. within > the kernel. > > There's little policy really, other than setting some general > parameters. NTPd can still provide the raw _network time_ > timestamps, as that is probably best fetched by user-space and fed > to the kernel.
At some point that stops being NTP. NTP has quite a bit of userland policy for filtering and managing a number of different network clocks (other ntp servers, PPS sources, etc).
>From what you're describing (direct offset from a hardware time device used to steer the clock directly in kernel), you might want to look at the STP code in s390 (stp_sync_clock).
thanks -john
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