Interesting data. What app are you using to generate the TCP flow, and what options are you using on it? Also, what are the scales on the x- and y-axes (seconds and decimal kilobytes)? I have some comments but they are only speculation without knowing this.
By "800Mb/s" do you megabytes or megabits? For ipoib, 800 megabytes/s (MB/s) seems very high and 800 megabits/s (Mb/s) seems very low. In my experience it gets 200-300 megabytes before running out of cpu (checksum calculations mainly). But I haven't looked at it in a while. Tom. At 03:07 PM 3/6/2007, chas williams - CONTRACTOR wrote: >while looking at some ipoib performance i had a chance to graph the >tcp flow in xplot (see http://www.xplot.org/). the graph appears very >strange and is attached to this message. > >the lower solid line represent acks coming back from the tcp server, the >up line represent the window size (i disabled window scaling btw, this >doesnt affect performance). the up/down arrows (they look like diamonds >due to scale) represent packets. this is a view from the tcp client. > >the initial part of the graph is tcp slow-start/congestion. what is >curious to how the returning acks (after slow start is finished) seem >to get quiet periodically. then the next ack that returns, then acks >the entire window. this seems to be leading to a very bursty behavior. > >i would normally expect to see two data packets followed by an >ack as can be seen between the 'burst' regions. > >i see aboue 800Mb/s (good put) between the hosts which i understand >to get typical for ipoib. there dont appear to be any link errors >either. > >so why the long pauses? > >ftp://ftp.cmf.nrl.navy.mil/pub/chas/ipoib.jpg >_______________________________________________ >general mailing list >[email protected] >http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general > >To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general _______________________________________________ general mailing list [email protected] http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
