Hi Beilei:
we used dpdk implement a user mode tcp protocol stack, and we are testing the
delay of a single packet.
however, on i40e NIC(XL710), the packet delay is higher than that of the
kernel. After some tests, we find that the time consuming may be the pahse when
i40e sends packet.(period from rte_eth_tx_burst to packet be sent)
The same test is performed on the ixgbe(82599) NIC. the delay is lower than
that in kernel.
I used dpdk-21.11 stable version.
I tried upgrading the i40e's firmware version to 9.10, but there was no
improvement.
Any suggestion?
Thank you.
The following is packet delay statistics of tcpdump:
i40e NIC:
410 10.373817 192.168.4.4 192.168.4.5 TCP 64
8877→58312 [ACK] Seq=6511 Ack=9642 Win=1048384 Len=0
10us
411 10.373827 192.168.4.4 192.168.4.5 TCP 94
58312→8877 [PSH, ACK] Seq=9642 Ack=6511 Win=1048512 Len=36
27us
412 10.373854 192.168.4.5 192.168.4.4 TCP 60
8877→58312 [ACK] Seq=6511 Ack=9678 Win=1048320 Len=0
9us
413 10.373863 192.168.4.5 192.168.4.4 TCP 90
58312→8877 [PSH, ACK] Seq=9642 Ack=6511 Win=1048512 Len=36
28us
414 10.373891 192.168.4.4 192.168.4.5 TCP 64
8877→58312 [ACK] Seq=6511 Ack=9678 Win=1048320 Len=0
11us
415 10.373902 192.168.4.4 192.168.4.5 TCP 94
58312→8877 [PSH, ACK] Seq=9678 Ack=6511 Win=1048512 Len=36
28us
416 10.373930 192.168.4.5 192.168.4.4 TCP 60
8877→58312 [ACK] Seq=6511 Ack=9714 Win=1048320 Len=0
11us
417 10.373941 192.168.4.5 192.168.4.4 TCP 90
58312→8877 [PSH, ACK] Seq=9678 Ack=6511 Win=1048512 Len=36
25us
418 10.373967 192.168.4.4 192.168.4.5 TCP 64
8877→58312 [ACK] Seq=6511 Ack=9714 Win=1048320 Len=0
11us
419 10.373978 192.168.4.4 192.168.4.5 TCP 94
58312→8877 [PSH, ACK] Seq=9714 Ack=6511 Win=1048512 Len=36
4us
420 10.373982 192.168.4.5 192.168.4.4 TCP 60
8877→58312 [ACK] Seq=6511 Ack=9750 Win=1048256 Len=0
ixgbe NIC:
110 13.235208 192.168.4.12 192.168.4.11 TCP 64
8877→58312 [ACK] Seq=6511 Ack=7266 Win=1047808 Len=0
10us
111 13.235218 192.168.4.12 192.168.4.11 TCP 94
58312→8877 [PSH, ACK] Seq=7266 Ack=6511 Win=1048512 Len=36
6us
112 13.235224 192.168.4.11 192.168.4.12 TCP 64
8877→58312 [ACK] Seq=6511 Ack=7302 Win=1047744 Len=0
10us
113 13.235234 192.168.4.11 192.168.4.12 TCP 94
58312→8877 [PSH, ACK] Seq=7266 Ack=6511 Win=1048512 Len=36
6us
114 13.235240 192.168.4.12 192.168.4.11 TCP 64
8877→58312 [ACK] Seq=6511 Ack=7302 Win=1047744 Len=0
11us
115 13.235251 192.168.4.12 192.168.4.11 TCP 94
58312→8877 [PSH, ACK] Seq=7302 Ack=6511 Win=1048512 Len=36
5us
116 13.235256 192.168.4.11 192.168.4.12 TCP 64
8877→58312 [ACK] Seq=6511 Ack=7338 Win=1047744 Len=0
11us
117 13.235267 192.168.4.11 192.168.4.12 TCP 94
58312→8877 [PSH, ACK] Seq=7302 Ack=6511 Win=1048512 Len=36
6us
118 13.235273 192.168.4.12 192.168.4.11 TCP 64
8877→58312 [ACK] Seq=6511 Ack=7338 Win=1047744 Len=0
10us
119 13.235283 192.168.4.12 192.168.4.11 TCP 94
58312→8877 [PSH, ACK] Seq=7338 Ack=6511 Win=1048512 Len=36
6us
120 13.235289 192.168.4.11 192.168.4.12 TCP 64
8877→58312 [ACK] Seq=6511 Ack=7374 Win=1047680 Len=0
