[libfabric-users] Libfabric questions

[Xiong, Jianxin]

Hi Niyaz,

The mlx provider is only available as part of Intel MPI package, which is only available for x86.

If you build libfabric from source, you can use the ucx provider instead. Similar to the mlx provider, the ucx provider runs on top of UCX.

The verbs provider runs on top of IB Verbs. The domain name “mlx5_0” is the device name of Mellanox NIC. It has nothing to do with the mlx provider, nor UCX.

The psm3 provider supports Intel NICs as well as Ethernet/IB/RoCE NICs from other vendors. Whether it is present on a machine depends on which package is installed. For example, if it is installed as part of the Intel Ethernet Fabric Suite package, then it is only available for x86_64. You may try to build it from libfabric source on other platforms, by adding “—enable-psm3” to the libfabric “configure” command line. If configure fails, check the content of “config.log” to see what is missing. This is an untested territory so I can’t guarantee that it will work.

The third question has been answered off-line, so I won’t repeat here.

-Jianxin

From: Libfabric-users <libfabric-users-bounces at lists.openfabrics.org> On Behalf Of Niyaz Murshed
Sent: Monday, May 6, 2024 6:16 PM
To: libfabric-users at lists.openfabrics.org
Cc: nd <nd at arm.com>
Subject: Re: [libfabric-users] Libfabric questions

Hello,

Can some please share some knowledge on this 😊

Regards,
Niyaz

From: Libfabric-users <libfabric-users-bounces at lists.openfabrics.org<mailto:libfabric-users-bounces at lists.openfabrics.org>> on behalf of Niyaz Murshed <Niyaz.Murshed at arm.com<mailto:Niyaz.Murshed at arm.com>>
Date: Tuesday, April 30, 2024 at 10:16 AM
To: libfabric-users at lists.openfabrics.org<mailto:libfabric-users at lists.openfabrics.org> <libfabric-users at lists.openfabrics.org<mailto:libfabric-users at lists.openfabrics.org>>
Subject: [libfabric-users] Libfabric questions
Hello all ,

I am trying to learn libfabric and have some basic questions. Please point me in the right direction.

I am running on ubuntu 22.04 with Mellanox ConnectX 7 NIC cards on an Arm platform (N1).

Question 1:
Is fi_mlx provider only available on x86?

Steps :
Installed UCX (as required in fi_mlx. https://ofiwg.github.io/libfabric/v1.8.0/man/fi_mlx.7.html)

# Library version: 1.18.0
Install libfabric

As per https://www.intel.com/content/www/us/en/developer/articles/technical/mpi-library-2019-over-libfabric.html  this is only available for infiniband devices.
However, in one of the presentations, it shows mlx also supports RoCE (https://ibb.co/bPhm0dp)

Could you please confirm if MLX provider will work on RoCE ? Other than UCX, do we need to install anything else to enable MLX provider?

In my current setup, I only see Verbs provider with doman : mlx
provider: verbs
    fabric: IB-0xfe80000000000000
    domain: mlx5_0
    version: 121.0
    type: FI_EP_MSG
    protocol: FI_PROTO_RDMA_CM_IB_RC

Is Verbs->mlx equivalent to verbs api wrapper over mlx provider?

Question 2:
Is PSM3 only available for intel NIC cards and only on x86 platform?
I have the same installation on x86 and Arm , however,  I see on x86 platform, the intel NICs has the following enabled

provider: psm3

    fabric: TCP-10.118.91.0/24

    domain: eno1

    version: 306.10

    type: FI_EP_RDM

    protocol: FI_PROTO_PSMX3

The same is not present on Arm platform.

Question 3:

My goal is to run rdma test between 2 application (RoCE).
I have 2 nics  on the server, one on numa0 and another on numa1. I have a loop cable from nic1 to nic2.
How can I make sure that the data is transferred  via the loop cable? Can this be done with fi_rma_bw app?



Regards,
Niyaz

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