loopback traffic can preempt the bandwidth?

When i use three hosts in 100 Gb,cx5. 1 loopback traffic and 2 rdma send, i find loopback traffic is 46G, but 2 rdma send traffic is 23Gb. Is there a mechanism to guarantee loopback traffic?

if i start a new rdma send, 3 rdma send share 46G bandwidth, and each of them is about 16Gb.

You use two card on the same server or you use dule port HCA ?