> However, if the clock selected by the BMC is switched off, loses its > network connection..., the second best clock is selected by the BMC and > becomes master. This clock may be less accurate and thus our slave clock > has to switch from one notion of time to another. Is that the conflict > you mentioned?
No you get situations where you have policy reasons for trusting particular clocks for particular things. So you may have a PTP or NTP clock providing basic system time but also have other PTP clocks that are actually being used for synchronization work. With NTP it's not so far been a big issue - NTP isn't used for industrial high precision control and the cases we end up with multiple NTP clocks it's on a virtualised systems where it is isolated. With high precision clocks you sometimes want to honour a specific PTP time source and use it rather than try and merge it with your other time sources (which may differ from the equipment elsewhere). What matters is things like all the parts of a several mile long conveyor belt of hot steel slab stopping at the same moment [1]. In lots of control applications you've got assorted different time planes which wish to talk their own time and you have to accept it, so we need to support that kind of use. I agree entirely the normal boring 'I installed my distro and..' case for PTP or for NTP is merging all the sources, running the algorithm and using the system time for it. Likewise almost all "normal" application code will be watching system time. Alan [1] Which was my first encounter with writing Vax/VMS assembly language _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
