On Sat, 2018-02-17 at 11:01 +0100, Oleksandr Natalenko wrote: > Hi. > > On pátek 16. února 2018 23:59:52 CET Eric Dumazet wrote: > > Well, no effect here on e1000e (1 Gbit) at least > > > > # ethtool -K eth3 sg off > > Actual changes: > > scatter-gather: off > > tx-scatter-gather: off > > tcp-segmentation-offload: off > > tx-tcp-segmentation: off [requested on] > > tx-tcp6-segmentation: off [requested on] > > generic-segmentation-offload: off [requested on] > > > > # tc qd replace dev eth3 root pfifo_fast > > # ./super_netperf 1 -H 7.7.7.84 -- -K cubic > > 941 > > # ./super_netperf 1 -H 7.7.7.84 -- -K bbr > > 941 > > # tc qd replace dev eth3 root fq > > # ./super_netperf 1 -H 7.7.7.84 -- -K cubic > > 941 > > # ./super_netperf 1 -H 7.7.7.84 -- -K bbr > > 941 > > # tc qd replace dev eth3 root fq_codel > > # ./super_netperf 1 -H 7.7.7.84 -- -K cubic > > 941 > > # ./super_netperf 1 -H 7.7.7.84 -- -K bbr > > 941 > > # > > That really looks strange to me. I'm able to reproduce the effect caused by > disabling scatter-gather even on the VM (using iperf3, as usual):
This must be some race condition in the code I added in TCP for self- pacing, when a sort timeout is programmed. Disabling SG means TCP cooks 1-MSS packets. I will take a look, probably after the (long) week-end : Tuesday. Thanks !
