Chapter 7. Configuring Soft-iWARP
Remote Direct Memory Access (RDMA) uses several libraries and protocols over an Ethernet such as iWARP, Soft-iWARP for performance improvement and aided programming interface.
Soft-iWARP is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview.
7.1. Overview of iWARP and Soft-iWARP
Remote direct memory access (RDMA) uses the iWARP over Ethernet for converged and low latency data transmission over TCP. By using standard Ethernet switches and the TCP/IP stack, iWARP routes traffic across the IP subnets. This provides flexibility to efficiently use the existing infrastructure. In Red Hat Enterprise Linux, multiple providers implement iWARP in their hardware network interface cards. For example, cxgb4, irdma, qedr, and so on.
Soft-iWARP (siw) is a software-based iWARP kernel driver and user library for Linux. It is a software-based RDMA device that provides a programming interface to RDMA hardware when attached to network interface cards. It provides an easy way to test and validate the RDMA environment.
7.2. Configuring Soft-iWARP
Soft-iWARP (siw) implements the iWARP Remote direct memory access (RDMA) transport over the Linux TCP/IP network stack. It enables a system with a standard Ethernet adapter to interoperate with an iWARP adapter or with another system running the Soft-iWARP driver or a host with the hardware that supports iWARP.
The Soft-iWARP feature is provided as a Technology Preview only. Technology Preview features are not supported with Red Hat production Service Level Agreements (SLAs), might not be functionally complete, and Red Hat does not recommend using them for production. These previews provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.
See Technology Preview Features Support Scope on the Red Hat Customer Portal for information about the support scope for Technology Preview features.
To configure Soft-iWARP, you can use this procedure in a script to run automatically when the system boots.
Prerequisites
- An Ethernet adapter is installed
Procedure
Install the
iproute,libibverbs,libibverbs-utils, andinfiniband-diagspackages:#yuminstall iproute libibverbs libibverbs-utils infiniband-diagsDisplay the RDMA links:
# rdma link showLoad the
siwkernel module:# modprobe siwAdd a new
siwdevice namedsiw0that uses theenp0s1interface:# rdma link add siw0 type siw netdev enp0s1
Verification
View the state of all RDMA links:
# rdma link show link siw0/1 state ACTIVE physical_state LINK_UP netdev enp0s1List the available RDMA devices:
# ibv_devices device node GUID ------ ---------------- siw0 0250b6fffea19d61You can use the
ibv_devinfoutility to display a detailed status:# ibv_devinfo siw0 hca_id: siw0 transport: iWARP (1) fw_ver: 0.0.0 node_guid: 0250:b6ff:fea1:9d61 sys_image_guid: 0250:b6ff:fea1:9d61 vendor_id: 0x626d74 vendor_part_id: 1 hw_ver: 0x0 phys_port_cnt: 1 port: 1 state: PORT_ACTIVE (4) max_mtu: 1024 (3) active_mtu: 1024 (3) sm_lid: 0 port_lid: 0 port_lmc: 0x00 link_layer: Ethernet
