On Tue, Mar 03, 2015 at 12:38:41AM -0800, Gary E. Miller wrote: > > > Ah, that explains a lot. Will that fix the jitter computation? > > > > Yes, the +/- value in the chronyc sources output should be smaller > > than 1 us now. It's mostly a cosmetic issue, it likely won't have any > > noticeable effect on the synchronization. The precision is the minimum > > allowed value of dispersion to avoid zero dispersion with low > > resolution refclocks, e.g. with microsecond SHM it is possible to get > > several samples with 0 offset, the dispersion would be zero and it > > would then break all kinds of things. > > Oh, great. > > First, why does chronyd not support uSec SHM? (I usually use the SOCK)
It does support both microsecond and nanosecond resolution in SHM. The default value of precision is set for microseconds, because using nanosecond resolution with microsecond precision is much better than using microsecond resolution with nanosecond precision as some samples could have three orders of magnitude smaller dispersion that others. > Two, so if I make it perfect (zero offset) things break? No, I was just trying to explain that the refclock precision prevents that problem. If several consecutive refclock samples have identical offset, the calculated dispersion might be zero, but it will be set to the precision before accumulating the sample to avoid division by zero etc. -- 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
