I made many runs with iperf3 ns->host, and the results are puzzling me. Over and over again, I see throughput practically collapse, with a two orders of magnitude decrease. Just to make sure this wasn't something introduced by me, I went back to the master branch and disabled the SO_PEEK_OFF feature. The result was the same. The below log shows typical run, but it is highly variable. Sometimes almost the whole series is in the 50-70 Gb/s range, and sometimes almost all in the 100-300 Mb/s range. When I added the kernel fix it didn't seem to make any difference. To me this is really worrying, and should be investigated. ///jon pasta NS->host (master branch, SO_PEEK_OFF disabled ----------------------------------------------------------- Server listening on 5201 (test #2) ----------------------------------------------------------- Accepted connection from 127.0.0.1, port 48354 [ 5] local 127.0.0.1 port 5201 connected to 127.0.0.1 port 48360 [ ID] Interval Transfer Bitrate [ 5] 0.00-1.00 sec 7.61 GBytes 65.3 Gbits/sec [ 5] 1.00-2.00 sec 7.59 GBytes 65.2 Gbits/sec [ 5] 2.00-3.00 sec 7.55 GBytes 64.8 Gbits/sec [ 5] 3.00-4.00 sec 7.69 GBytes 66.1 Gbits/sec [ 5] 4.00-5.00 sec 7.55 GBytes 64.8 Gbits/sec [ 5] 5.00-6.00 sec 7.60 GBytes 65.3 Gbits/sec [ 5] 6.00-7.00 sec 7.52 GBytes 64.6 Gbits/sec [ 5] 7.00-8.00 sec 1.02 GBytes 8.73 Gbits/sec [ 5] 8.00-9.00 sec 3.50 MBytes 29.4 Mbits/sec [ 5] 9.00-10.00 sec 17.2 MBytes 145 Mbits/sec [ 5] 10.00-11.00 sec 64.0 MBytes 537 Mbits/sec [ 5] 11.00-12.00 sec 24.1 MBytes 202 Mbits/sec [ 5] 12.00-13.00 sec 25.4 MBytes 213 Mbits/sec [ 5] 13.00-14.00 sec 24.9 MBytes 209 Mbits/sec [ 5] 14.00-15.00 sec 21.4 MBytes 179 Mbits/sec [ 5] 15.00-16.00 sec 32.0 MBytes 268 Mbits/sec [ 5] 16.00-17.00 sec 10.9 MBytes 91.2 Mbits/sec [ 5] 17.00-18.00 sec 27.6 MBytes 232 Mbits/sec [ 5] 18.00-19.00 sec 75.6 MBytes 634 Mbits/sec [ 5] 19.00-20.00 sec 21.1 MBytes 177 Mbits/sec [ 5] 20.00-21.00 sec 109 MBytes 912 Mbits/sec [ 5] 21.00-22.00 sec 23.9 MBytes 200 Mbits/sec [ 5] 22.00-23.00 sec 62.6 MBytes 525 Mbits/sec [ 5] 23.00-24.00 sec 34.5 MBytes 289 Mbits/sec [ 5] 24.00-25.00 sec 54.4 MBytes 456 Mbits/sec [ 5] 25.00-26.00 sec 14.1 MBytes 118 Mbits/sec [ 5] 26.00-27.00 sec 38.8 MBytes 325 Mbits/sec [ 5] 27.00-28.00 sec 95.0 MBytes 797 Mbits/sec [ 5] 28.00-29.00 sec 23.2 MBytes 195 Mbits/sec [ 5] 29.00-30.00 sec 71.9 MBytes 603 Mbits/sec [ 5] 30.00-31.00 sec 28.8 MBytes 241 Mbits/sec [ 5] 31.00-32.00 sec 34.8 MBytes 292 Mbits/sec [ 5] 32.00-33.00 sec 19.4 MBytes 163 Mbits/sec [ 5] 33.00-34.00 sec 39.1 MBytes 328 Mbits/sec [ 5] 34.00-35.00 sec 31.4 MBytes 263 Mbits/sec [ 5] 35.00-36.00 sec 28.2 MBytes 237 Mbits/sec [ 5] 36.00-37.00 sec 48.5 MBytes 407 Mbits/sec [ 5] 37.00-38.00 sec 23.4 MBytes 196 Mbits/sec [ 5] 38.00-39.00 sec 71.4 MBytes 599 Mbits/sec [ 5] 39.00-40.00 sec 41.4 MBytes 347 Mbits/sec [ 5] 40.00-41.00 sec 15.2 MBytes 128 Mbits/sec [ 5] 41.00-42.00 sec 34.1 MBytes 286 Mbits/sec [ 5] 42.00-43.00 sec 31.1 MBytes 261 Mbits/sec [ 5] 43.00-44.00 sec 61.5 MBytes 516 Mbits/sec [ 5] 44.00-45.00 sec 38.2 MBytes 321 Mbits/sec [ 5] 45.00-46.00 sec 34.2 MBytes 287 Mbits/sec [ 5] 46.00-47.00 sec 33.8 MBytes 283 Mbits/sec [ 5] 47.00-48.00 sec 7.12 MBytes 59.8 Mbits/sec [ 5] 48.00-49.00 sec 97.4 MBytes 817 Mbits/sec [ 5] 49.00-50.00 sec 13.6 MBytes 114 Mbits/sec - - - - - - - - - - - - - - - - - - - - - - - - - [ ID] Interval Transfer Bitrate [ 5] 0.00-50.00 sec 55.7 GBytes 9.57 Gbits/sec receiver ----------------------------------------------------------- Server listening on 5201 (test #3) -----------------------------------------------------------