On Fri, 2 Nov 2018, Miroslav Lichvar wrote: > On Thu, Nov 01, 2018 at 07:03:37PM +0100, Thomas Gleixner wrote: > > On Thu, 1 Nov 2018, John Stultz wrote: > > > On Thu, Nov 1, 2018 at 10:44 AM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > > > > On Tue, 23 Oct 2018, John Stultz wrote: > > > >> However, to be correct, the ntp adjustments made would have to be made > > > >> to both the base interval + error, which mucks the math up a fair bit. > > > > > > > > Hmm, confused as usual. Why would you need to do anything like that? > > > > > > Because the NTP adjustment is done off of what is now the raw clock. > > > If the raw clock is "corrected" the ppb adjustment has to be done off > > > of that corrected rate. > > > > Sure, but why would that require any change? Right now the raw clock is > > slightly off and you correct clock monotonic against NTP. So with that > > extra correction you just see a slightly different raw clock slew and work > > from there. > > It makes sense to me. > > I think there are basically two different ways how it could be done. > One is to correct the frequency of the raw clock, on which sits the > mono/real clock. The other is to create a new raw clock which is > separate from the mono/real clock, and add an offset to the NTP > frequency to match the frequencies of the two clocks when not > synchronized by NTP/PTP. The latter would provide a more stable > mono/real clock. > > clocksource -> MONOTONIC_RAW -> MONOTONIC/REALTIME > > or > > clocksource -> ? -> MONOTONIC_RAW > -> MONOTONIC/REALTIME That's what we have now. At least I don't see how the raw thing is coupled in NTP. Thanks, tglx
