> > The FEC of i.MX8MP-EVK has dma_coherent=false, and as I mentioned > > above, I did not see an obvious difference in the performance. :( > > That is surprising - given the results. > > (see below, lack of perf/diff might be caused by Ethernet flow-control). > > > > >>> The result of the current modification. > >>> root@imx8mpevk:~# ./xdp2 eth0 > >>> proto 17: 260180 pkt/s > >> > >> These results are*significantly* better than reported in patch-1. > >> What happened?!? > >> > > The test environment is slightly different, in patch-1, the FEC port > > was directly connected to the port of another board. But in the latest > > test, the ports of the two boards were connected to a switch, so the > > ports of the two boards are not directly connected. > > > > Hmm, I've seen this kind of perf behavior of direct-connected or via switch > before. The mistake I made was, that I had not disabled Ethernet flow-control. > The xdp2 XDP_TX program will swap the mac addresses, and send the packet > back to the packet generator (running pktgen), which will get overloaded > itself and starts sending Ethernet flow-control pause frames. > > Command line to disable: > # ethtool -A eth0 rx off tx off > > Can I ask/get you to make sure that Ethernet flow-control is disabled (on > both generator and DUT (to be on safe-side)) and run the test again? > The flow-control was not disabled before, so according to your suggestion, I disable the flow-control on the both boards and run the test again, the performance is slightly improved, but still can not see a clear difference between the two methods. Below are the results. Result: use "sync_dma_len" method root@imx8mpevk:~# ./xdp2 eth0 proto 17: 258886 pkt/s proto 17: 258879 pkt/s proto 17: 258872 pkt/s proto 17: 258312 pkt/s proto 17: 258926 pkt/s proto 17: 259057 pkt/s proto 17: 258437 pkt/s proto 17: 259242 pkt/s proto 17: 258665 pkt/s proto 17: 258779 pkt/s proto 17: 259209 pkt/s Result: use the current method root@imx8mpevk:~# ./xdp2 eth0 proto 17: 258752 pkt/s proto 17: 258672 pkt/s proto 17: 258317 pkt/s proto 17: 258787 pkt/s proto 17: 258757 pkt/s proto 17: 258542 pkt/s proto 17: 258829 pkt/s proto 17: 258480 pkt/s proto 17: 258859 pkt/s proto 17: 258918 pkt/s proto 17: 258782 pkt/s proto 17: 259086 pkt/s proto 17: 258337 pkt/s
