Hello everyone, Recently, I used netperf to test the TCP performance on loopback interface on my 2 nodes, one is installed kernel 4.4.103 and the other is 3.12.61
netperf -l 100 -t TCP_RR netperf -l 100 -t TCP_RR -- -D In both cases, I see that the throughput on 4.4.103 is about just 1/2 in comparing with 3.12.61 node # netperf -l 100 -t TCP_RR MIGRATED TCP REQUEST/RESPONSE TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost () port 0 AF_INET : first burst 0 Local /Remote Socket Size Request Resp. Elapsed Trans. Send Recv Size Size Time Rate bytes Bytes bytes bytes secs. per sec 16384 87380 1 1 100.00 37714.68 16384 87380 netperf -l 100 -t TCP_RR MIGRATED TCP REQUEST/RESPONSE TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost () port 0 AF_INET : first burst 0 Local /Remote Socket Size Request Resp. Elapsed Trans. Send Recv Size Size Time Rate bytes Bytes bytes bytes secs. per sec 16384 87380 1 1 100.00 64038.41 16384 87380 When running tcpdump to capture all packets in loopback interface, I see that during 200s capture, the number of packets on loopback of 4.4.103 is double the number of packets in 3.12.61? Could you please let me know if it can cause the low throughput as above? Do we have any tuning for TCP on loopback to improve the performace (actually the low throughput also happens with UDP) or if we have any known performance issue in 4.4 kernel on loopback? Thanks a lot, Brs, Naruto
