[mpich-discuss] Selecting a specific libfabric fabric/domain

[Wesley Bland]

Hi Eric,

There isn’t a way of doing that at the moment with MPICH (I’m not sure if any particular OFI providers have support for this through environment variables or something else). It will open whichever one OFI gives you first (assuming all other capability bits are the same).

Thanks,
Wesley

> On Feb 18, 2019, at 1:40 PM, eric--- via discuss <discuss at mpich.org> wrote:
> 
> Hi there,
> 
> I'm using MPICH with ch4:ofi, and I'm wondering how to select which fabric/domain MPICH will open. I can select the provider with MPIR_CVAR_OFI_USE_PROVIDER, but suppose that the provider has two disjoint fabrics with equivalent capabilities. E.g., suppose I have two ethernet NICs connected to private networks:
> 
> provider: sockets
>    fabric: 192.168.1.0/24
>    domain: eth0
>    version: 2.0
>    type: FI_EP_RDM
>    protocol: FI_PROTO_SOCK_TCP
> provider: sockets
>    fabric: 10.0.1.0/24
>    domain: eth1
>    version: 2.0
>    type: FI_EP_RDM
>    protocol: FI_PROTO_SOCK_TCP
> 
> 
> Is there a tunable to pick which will be used?
> 
> Thanks,
> Eric
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