TCP_RR test weirdness

Sam Riesland (
Thu, 15 Jul 1999 10:49:28 -0700 (PDT)

I am running netperf with the following command line... where $RR_SIZE is
the size of the packets I'm sending and receiving.

/netperf -l 5 -H astrolab3 -i 10,3 -I 99 -d -t TCP_RR -- -r $RR_SIZE

And for some reason when I set $RR_SIZE (the send,recieve packet size) to
between "1449,1449" and "2171,2171" the Transfer Rate drops way down to
about 99 bytes per second from somewhere in the thousands. Also the same
thing occurs between 4345 and 5067... and then again between 7241 and
7963. So every 2174 bytes there is a 722 byte block in which the Transfer
Rate drops down to around 99 bytes. I can get rid of this problem by
using the -D switch (TCP_NODELAY set)... but this behavior seems a bit
strange. Is this a netperf problem? Has anyone else run into anything