On Tue, Mar 17, 2015 at 05:28:45PM +0000, Chandra Mallela wrote: > 512 sync packets are a reasonable rate for frequency corrections. In case of > ToD, the fractional HW arithmetic (2^-16) can give you capability to achieve > the highest accuracy possible, if the stack can supply such fine-grained > values.
AFAIK the Linux time stamping and clock interfaces are limited to nanoseconds. As an excersise to see when things start to fall apart sync rate of -9 may be interesting, but I'm not sure if it there is any practical value. > As for 'what is that supposed to achieve?', in ideal scenario, targeting > 50pbb for CDMA is what I look at. I am further trying to analyze SyncE > requirements from 1588 perspective, which seems too tough at this moment due > to OS scheduling jitter itself. Do you have any specifications on the clock stability and jitter? Unless you are dealing with some very unstable clocks or large jitters, with careful PI configuration keeping the frequency error below 50 ppb shouldn't be difficult even at the default 1Hz sync rate. -- 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-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linuxptp-users
