In certain fabric configurations, InfiniBand packets for a given QP may take up different paths in a network from source to destination. This results into packets being received in an out-of-order manner. These packets can now be handled instead of being dropped, in order to avoid retransmission. Data will be placed into host memory in an out-of-order manner when out of order messages are received.
ibv_exp_create_dct
IBV_EXP_DCT_OOO_RW_DATA_PLACEMENT
MLX5_RELAXED_PACKET_ORDERING_ON
IBV_EXP_DEVICE_ATTR_OOO_CAPS
OOO feature is enabled by default in RDMA-Core.