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Subject: Re: [OMPI devel] RFC: Linuxes shipping libibverbs
From: Pavel Shamis (Pasha) (pasha_at_[hidden])
Date: 2008-05-21 11:32:30


I'm agree with Brian. We may add to the warning message detailed
description how to disable it.

Pasha

Brian W. Barrett wrote:
> I think having a parameter to turn off the warning is a great idea. So
> great in fact, that it already exists in the trunk and v1.2 :)! Setting
> the default value for the btl_base_warn_component_unused flag from 0 to 1
> will have the desired effect.
>
> I'm not sure I agree with setting the default to 0, however. The warning
> has proven extremely useful for diagnosing that IB (or less often GM or
> MX) isn't properly configured on a compute node due to some random error.
> It's trivially easy for any packaging group to have the line
>
> btl_base_warn_component_unused = 0
>
> added to $prefix/etc/openmpi-mca-params.conf during the install phase of
> the package build (indeed, our simple build scripts at LANL used to do
> this on a regular bases due to our need to tweek the OOB to keep IPoIB
> happier at scale).
>
> I think keeping the Debian guys happy is a good thing. Giving them an
> easy way to turn off silly warnings is a good thing. Removing a known
> useful warning to help them doesn't seem like a good thing.
>
>
> Brian
>
>
> On Wed, 21 May 2008, Jeff Squyres wrote:
>
>
>> What: Change default in openib BTL to not complain if no OpenFabrics
>> devices are found
>>
>> Why: Many linuxes are shipping libibverbs these days, but most users
>> still don't have OpenFabrics hardware
>>
>> Where: btl_openib_component.c
>>
>> When: For v1.3
>>
>> Timeout: Teleconf, 27 May 2008
>>
>> Short version
>> =============
>>
>> Many major linuxes are shipping libibverbs by default these days.
>> OMPI will therefore build the openib BTL by default, but then
>> complains at run time when there's no OpenFabrics hardware.
>>
>> We should change the default in v1.3 to not complain if there is no
>> OpenFabrics devices found (perhaps have an MCA param to enable the
>> warning if desired).
>>
>> Longer version
>> ==============
>>
>> I just got a request from the Debian Open MPI package maintainers to
>> include the following in the default openmpi-mca-params.conf for the
>> OMPI v1.2 package:
>>
>> # Disable the use of InfiniBand
>> # btl = ^openib
>>
>> Having this in the openmpi-mca-params.conf gives Debian an easy
>> documentation path for users to shut up these warnings when they build
>> on machines with libibverbs present but no OpenFabrics hardware.
>>
>> I think that this is fine for the v1.2 series (and will file a CMR for
>> it). But for v1.3, I think we should change the default.
>>
>> The vast majority of users will not have OpenFabrics devices, and we
>> should therefore not complain if we can't find any at run-time. We
>> can/should still complain if we find OpenFabrics devices but no active
>> ports (i.e., don't change this behavior).
>>
>> But for optimizing the common case: I think we should (by default) not
>> print a warning if no OpenFabrics devices are found. We can also
>> [easily] have an MCA parameter that *will* display a warning if no
>> OpenFabrics devices are found.
>>
>>
>>
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