What are InfiniBand verbs?
IB verbs are abstract representations of functions. You can think of IB verbs as functions/methods that have to be offered by an (IB)-API. You might wonder, why there is an article on InfiniBand on a cloud computing blog.
What is InfiniBand’s API?
InfiniBand has no specific standard application programming interface (API). The standard only lists a set of verbs such as ibv_open_device or ibv_post_send, which are abstract representations of functions or methods that must exist. The syntax of these functions is left to the vendors. Sometimes for reference this is called the verbs API.
Are You Fed up with all those new abbreviations in InfiniBand?
By now you should be quite fed up with all those new abbreviations. But especially when programming with the ibverbs library, it is more than helpful knowing these abbreviations. Therefore here a short recap and clearer overview of those InfiniBand concepts needed for communication.
What are the characteristics of InfiniBand?
Specification 1 Performance. Links can be aggregated: most systems use a 4× aggregate. 2 Topology. InfiniBand uses a switched fabric topology, as opposed to early shared medium Ethernet. 3 Messages. InfiniBand transmits data in packets of up to 4 KB that are taken together to form a message. 4 Physical interconnection.
“Verbs” is the term used for both the seman- tic description of the interface in the InfiniBand Architecture Specifications, and the name used for the functions defined in the widely used OpenFabrics Alliance (OFA) implementation of the software interface to InfiniBand.
What is verbs RDMA?
Verb types: One-sided verbs (RDMA operations) operate directly on a remote node’s memory, bypassing its CPU, and include RDMA reads, writes, and atomic operations. Two-sided verbs include the send and receive verbs; their functionality resembles send() and recv() functions in traditional sockets programming.
What is Ibverbs?
libibverbs is a library that allows userspace processes to use RDMA “verbs” to perform high-throughput, low-latency network operations for both Infiniband (according to the Infiniband specifications) and iWarp (iWARP verbs specifications).
Is InfiniBand a RDMA?
InfiniBand provides remote direct memory access (RDMA) capabilities for low CPU overhead.
What is RDMA used for?
Overview. Remote Direct Memory Access (RDMA) is an extension of the Direct Memory Access (DMA) technology, which is the ability to access host memory directly without CPU intervention. RDMA allows for accessing memory data from one host to another.
What is the queue pair in InfiniBand?
Queue Pair (QP), a set of a Send Queue (SQ), a Receive Queue (RQ), and a Completion Queue (CQ) HCAs communicate with each other using work queues.
What is the queue pair in Infiniband?
How fast is InfiniBand?
DDR InfiniBand provides a 20 Gbps link. 8b/10b encoding is used which provides actual speeds of 16 Gbps.
What is RDMA and how does it work?
In computing, remote direct memory access (RDMA) is a direct memory access from the memory of one computer into that of another without involving either one’s operating system. This permits high-throughput, low-latency networking, which is especially useful in massively parallel computer clusters.