From Linux NFS

Soft ROCE is a software implementation of RoCE that allows RDMA to be used on any Ethernet adapter. It is available in Linux kernels after 4.8. The following instructions are suitable for most of the latest linux distributions.

Client and Server Common Setup

• Check for the rdma_rxe kernel module. If you don't have it, then enable the following Kconfig options and rebuild your kernel

CONFIG_INFINIBAND
CONFIG_INFINIBAND_RDMAVT
CONFIG_RDMA_RXE

• Install the iproute2 package and use the rdma link add command to load the module and start an RDMA interface. Note that this does not survive reboots.
• Comment: rxe_cfg has been deprecated from 01/2020, use rdma command instead.

[foo@linux-bar ~]$ sudo rdma link add rxe0 type rxe netdev eth0
[foo@linux-bar ~]$ sudo rdma link
link rxe0/1 state ACTIVE physical_state LINK_UP netdev eth0

Ping Test

• Start an rping server on one machine

[foo@linux-bar ~]$ sudo rping -s -v -C 3
server ping data: rdma-ping-0: ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqr
server ping data: rdma-ping-1: BCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrs
server ping data: rdma-ping-2: CDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrst
server DISCONNECT EVENT...
wait for RDMA_READ_ADV state 10

• Now check that the connection works from another machine

[foo@linux-bor ~]$ sudo rping -c -a 192.168.122.40 -v -C 3
ping data: rdma-ping-0: ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqr
ping data: rdma-ping-1: BCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrs
ping data: rdma-ping-2: CDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrst
client DISCONNECT EVENT...

NFS Setup

Server

• Install the nfs-utils package and enable rdma from /etc/nfs.conf and restart service nfs-server

[foo@linux-bar]$ sudo sed -i '/rdma/{s/^#//; s/rdma=n/rdma=y/}' /etc/nfs.conf
[foo@linux-bar]$ grep -v ^# /etc/nfs.conf
[general]
[exportfs]
[gssd]
 use-gss-proxy=1
[lockd]
[mountd]
[nfsdcld]
[nfsdcltrack]
[nfsd]
 rdma=y
 rdma-port=20049
[statd]
[sm-notify]
[foo@linux-bar]$ sudo mkdir -p /expdir
[foo@linux-bar]$ sudo bash -c 'echo "/expdir *(rw,no_root_squash)" >/etc/exports'
[foo@linux-bar]$ sudo systemctl restart nfs-server

Client

• Install the nfs-utils package and do nfs mount
• Mount the server to check that it worked

[foo@linux-bor]$ sudo mount -o rdma,port=20049,vers=4.2 192.168.122.40:/expdir /mnt/nfsmp
[foo@linux-bor]$ mount | grep proto=rdma
192.168.122.40:/expdir on /mnt/nfsmp type nfs4 (rw,relatime,vers=4.2,rsize=262144,wsize=262144,namlen=255,hard,proto=rdma,port=20049,timeo=600,retrans=2,sec=sys,clientaddr=192.168.122.161,local_lock=none,addr=192.168.122.40)

See Also

• Mellanox's softRoCE setup guide
• Red Hat's softRoCE setup guide
• Rdma-core's documentation
• The rdma man page
• The rxe_cfg man page
• rxe_cfg deprecated