rdma_bw: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/rdma_bw - from package: perftest

You may install the required package with command yum install {package}

Error in other languages:
rdma_bw: bevel nie gevind nie
rdma_bw: comandă negăsită
rdma_bw: comando não encontrado
rdma_bw: commande introuvable
rdma_bw: command not found
rdma_bw: käsku ei ole
rdma_bw: không tìm thấy lệnh
rdma_bw: komanda nerasta
rdma_bw: Kommando nicht gefunden.
rdma_bw: kommandot finns inte
rdma_bw: komut yok
rdma_bw: nie znaleziono polecenia
rdma_bw: níor aimsíodh an t-ordú
rdma_bw: no se encontró la orden
rdma_bw: no s'ha trobat l'ordre
rdma_bw: opdracht niet gevonden
rdma_bw: parancs nem található
rdma_bw: perintah tidak ditemukan
rdma_bw: príkaz nenájdený
rdma_bw: příkaz nenalezen
rdma_bw: команда не найдена
rdma_bw: командата не е открита
rdma_bw: 命令找不到
rdma_bw: コマンドが見つかりません