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Subject: Re: [OMPI devel] RFC: Linuxes shipping libibverbs
From: Terry Dontje (Terry.Dontje_at_[hidden])
Date: 2008-05-22 06:50:48


Jeff Squyres wrote:
> Brian and I chatted a bit about this off-list, and I think we're in
> agreement now:
>
> - do not change the default value or meaning of
> btl_base_want_component_unsed.
>
> - major point of confusion: the openib BTL is actually fairly unique
> in that it can (and does) tell the difference between "there are no
> devices present" and "there are devices, but something went wrong".
> Other BTL's have network interfaces that can't tell the difference and
> can *only* call the no_nics function, regardless of whether there are
> no relevant network interfaces or some error occurred during
> initialization.
>
> - so a reasonable solution would be an openib-BTL-specific mechanism
> that doesn't call the no_nics function (to display that
> btl_base_want_component_unused) if there are no verbs-capable devices
> found because of the fact that mainline Linuxes are starting to ship
> libibverbs. Specific mechanism TBD; likely to be an openib MCA param.
>
>
So, if you are delivering something similar to a BTL for myrinet you
will see the message but
the belief is this is necessary since there isn't enough granularity in
the error reporting of the
device to feel comfortable enough as to whether the user want the device
to be used?

Won't udapl have a similar issue here or does it not get built by
default when OFED is built?

FWIW, our distribution actually turns off btl_base_want_component_unused
because it seemed
the majority of our cases would be that users would false positive
sights of the message.

--td

> On May 21, 2008, at 9:56 PM, Jeff Squyres wrote:
>
>
>> On May 21, 2008, at 5:02 PM, Brian W. Barrett wrote:
>>
>>
>>> If this is true (for some reason I thought it wasn't), then I think
>>> we'd
>>> actually be ok with your proposal, but you're right, you'd need
>>> something
>>> new in the IB btl. I'm not concerned about the dual rail issue -- if
>>> you're smart enough to configure dual rail IB, you're smart enough to
>>> figure out OMPI mca params. I'm not sure the same is true for a
>>> simple
>>> delivered from the white box vendor IB setup that barely works on a
>>> good
>>> day (and unfortunately, there seems to be evidence that these exist).
>>>
>> I'm not sure I understand what you're saying -- you agree, but what
>> "new" do you think we need in the openib BTL? The MCA params saying
>> which ports you expect to be ACTIVE?
>>
>> --
>> Jeff Squyres
>> Cisco Systems
>>
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>
>
>