I think my overall point regarding precision and granularity is that I am thinking in terms of babel in high speed switch/routers at 100+GigE and implemented in hardware, with timestamping even more accurate than what even ptp can achieve.
but I will wait til babel 3.0. :) On Thu, Mar 19, 2015 at 7:45 PM, Dave Taht <[email protected]> wrote: > On Thu, Mar 19, 2015 at 2:36 PM, Juliusz Chroboczek > <[email protected]> wrote: >>> I still kind of like getting down to ns resolution here. A single 64 >>> byte packet at 10gigE takes like 64ns. >> >> Dave, >> >> As Baptiste mentioned, babeld measures latencies with a granularity of >> 1盜, and a precision of a few hundred 盜. That means we have two to three >> orders of magnitude to grow. We've already changed the protocol once to >> reduce the granularity, at your prompting, and there's no point doing that >> again until the precision becomes comparable to the granularity. > > I'll live with it as it is. Sorry for the noise. I note that I think > you tried to type in us above, and it shows up as cute little houses > on my mailer. :) > >> Dave, if you'd like this to happen, you'll want to produce experimental >> data that show that the timestamps' granularity is an actual limitation. > > Well, I'd have to rope in some 10GigE users of babel to try it fully > and produce patches that did what I wanted to autosense capacity and > utilization. Those are still quite feasible, and I figure I could > treat long term averages below 1us as a means of better sensing the > higher bandwidths. > > I had done some measurements using other tools (isoburst and some > kernel stuff) and got WAY better precision than you got. Jesper got > even better, as noted on this thread earlier. > > So it would be best for me to finally sink the time into doing up high > speed network RTT based routing metrics the way I envisioned them 1.5 > years ago, and perhaps I'll have time this summer to try that, > piecemeal, whilst we test the upcoming deployment of all the other > stuff. > > I am happy that 10GigE seems likely to become more common in the > future, with dual 10GigE nics on the latest intel socs. I have > delusions of connecting up rings of machines again without a central > switch, but I guess it's saner to bridge them all together. > >> -- Juliusz > > > > -- > Dave Täht > Let's make wifi fast, less jittery and reliable again! > > https://plus.google.com/u/0/107942175615993706558/posts/TVX3o84jjmb -- Dave Täht Let's make wifi fast, less jittery and reliable again! https://plus.google.com/u/0/107942175615993706558/posts/TVX3o84jjmb _______________________________________________ Babel-users mailing list [email protected] http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/babel-users
