1. Background While testing the performance of NFS Over RDMA, I found that reading a 4M file could actually reach 45GB/s. 1 2 3 fio -numjobs=128 -fallocate=none -iodepth=2 -ioengine=libaio -direct=1 -rw=read -bs=4M --group_reporting -size=100m -time_based -runtime=30 -name=fio-test -directory=/data1/nfs READ: bw=42.3GiB/s (45.4GB/s), 42.3GiB/s-42.3GiB/s (45.4GB/s-45.4GB/s), io=1269GiB (1363GB), run=30019-30019msec Yet the disk’s 4M multi-threaded read performance is only 6 GB/s.