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Man pages of linux command ibstat and ibv_devinfo say 

ibstat - query basic status of InfiniBand device(s)
ibv_devinfo - query RDMA devices

In this context, what is the difference between Infiniband devices and RDMA devices? And in what circumstances, are the outputs of these two commands different (i.e. they differ in the list of devices output)?

Sagar Jha
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1 Answers1

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There is no difference between "InfiniBand device" and "RDMA device" in this context. It is just two separate tools written by different people that prefer different type of wording.

Both of these tools will provide you with the same devices.

That said, these two tools are completely different:

  • ibstat gets its info from sysfs - it gets whatever info is there, and that info is put by an HCA driver
  • ibv_devinfo uses verbs to query the device and provide you with the info

There are some bits of info that you can see with one tool but not with other, but again, in general, you will see the same devices with same info.

kliteyn
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    In general, Infiniband is a protocol which implements RDMA (remote direct memory access). Infiniband supports the WRITE, READ and ATOMIC verbs, which can access the memory of remote setups without involving the remote setups' CPUs – Tgilgul Nov 25 '17 at 14:18
  • I think @Tgigul gets at the answer I believe is important. You can have Remote Direct Memory Access (RDMA) without Infiniband. Many network architectures implement RDMA, including Infiniband. In the past, I have used Soft RoCE (Software RDMA over Converged Ethernet) to write OFED code, since I can do this on my laptop without Infiniband hardware. – edt11x Jun 27 '23 at 15:28