On Wed, Feb 25, 2015 at 03:53:26PM +0100, Jiri Benc wrote: > On Tue, 24 Feb 2015 21:33:49 +0000, Keller, Jacob E wrote: > > I do not believe Jiri is right. I ran a similar config and it appeared > > to work fine, without crazy clock jumping. Chronyd simply took the SHM > > reference and tuned the system clock over time, because the ntpshm > > servo presents itself to the ntp daemon. > > You're right and I'm not. The ntpshm servo always sets the > SERVO_UNLOCKED state in the sample() callback, thus it never sets any > clock. I didn't know that and I dislike that very much. This is a gross > hack. Not mentioning it's not documented in the man page.
The man page says the clock is synchronized by another process. > Miroslav, any chance to improve this to be better understandable to > users? Possibly, any suggestions? > From the user point of view, the shm is just another time > source. In the code, it could be implemented as a fake clock (as you > need at least two clocks for phc2sys to do anything) driven by this > special servo. I don't follow. What would the fake clock do? > Requiring the user to add a random second clock for this > to work (be it a system clock or a different PHC) is very confusing. It's not a random clock, it's the clock that is synchronized by the SHM consumer, i.e. the system clock with chronyd/ntpd. SHM samples contain timestamps from both clocks (PHC and system clock). -- Miroslav Lichvar ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
