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Subject: Re: [OMPI users] RDMACM Differences
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-03-01 13:02:40

On Feb 28, 2011, at 12:49 PM, Jagga Soorma wrote:

> -bash-3.2$ mpiexec --mca btl openib,self -mca btl_openib_warn_default_gid_
> prefix 0 -np 2 --hostfile mpihosts /home/jagga/osu-micro-benchmarks-3.3/openmpi/ofed-1.5.2/bin/osu_latency

Your use of btl_openib_warn_default_gid_prefix may have brought up a subtle issue in Open MPI's verbs support. More below.

> # OSU MPI Latency Test v3.3
> # Size Latency (us)
> [amber04][[10252,1],1][connect/btl_openib_connect_oob.c:325:qp_connect_all] error modifing QP to RTR errno says Invalid argument
> [amber04][[10252,1],1][connect/btl_openib_connect_oob.c:815:rml_recv_cb] error in endpoint reply start connect

Looking at this error message and your ibv_devinfo output:

> [root_at_amber03 ~]# ibv_devinfo
> hca_id: mlx4_0
> transport: InfiniBand (0)
> fw_ver: 2.7.9294
> node_guid: 78e7:d103:0021:8884
> sys_image_guid: 78e7:d103:0021:8887
> vendor_id: 0x02c9
> vendor_part_id: 26438
> hw_ver: 0xB0
> board_id: HP_0200000003
> phys_port_cnt: 2
> port: 1
> state: PORT_ACTIVE (4)
> max_mtu: 2048 (4)
> active_mtu: 2048 (4)
> sm_lid: 1
> port_lid: 20
> port_lmc: 0x00
> link_layer: IB
> port: 2
> state: PORT_ACTIVE (4)
> max_mtu: 2048 (4)
> active_mtu: 1024 (3)
> sm_lid: 0
> port_lid: 0
> port_lmc: 0x00
> link_layer: Ethernet

It looks like you have 1 HCA port as IB and the other at Ethernet.

I'm wondering if OMPI is not taking the device transport into account and is *only* using the subnet ID to determine reachability (i.e., I'm wondering if we didn't anticipate multiple devices/ports with the same subnet ID but with different transports). I pointed this out to Mellanox yesterday; I think they're following up on it.

In the meantime, a workaround might be to set a non-default subnet ID on your IB network. That should allow Open MPI to tell these networks apart without additional help.

Jeff Squyres
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