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Subject: Re: [OMPI devel] matching code rewrite in OB1
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2007-12-12 17:04:07


Was Rich referring to ensuring that the test codes checked that their
payloads were correct (and not re-assembled in the wrong order)?

On Dec 12, 2007, at 4:10 PM, Brian W. Barrett wrote:

> On Wed, 12 Dec 2007, Gleb Natapov wrote:
>
>> On Wed, Dec 12, 2007 at 03:46:10PM -0500, Richard Graham wrote:
>>> This is better than nothing, but really not very helpful for
>>> looking at the
>>> specific issues that can arise with this, unless these systems
>>> have several
>>> parallel networks, with tests that will generate a lot of parallel
>>> network
>>> traffic, and be able to self check for out-of-order received -
>>> i.e. this
>>> needs to be encoded into the payload for verification purposes.
>>> There are
>>> some out-of-order scenarios that need to be generated and
>>> checked. I think
>>> that George may have a system that will be good for this sort of
>>> testing.
>>>
>> I am running various test with multiple networks right now. I use
>> several IB BTLs and TCP BTL simultaneously. I see many reordered
>> messages and all tests were OK till now, but they don't encode
>> message sequence in a payload as far as I know. I'll change one of
>> them to do so.
>
> Other than Rich's comment that we need sequence numbers, why add
> them? We
> haven't had them for non-matching packets for the last 3 years in
> Open MPI
> (ie, forever), and I can't see why we would need them. Yes, we need
> sequence numbers for match headers to make sure MPI ordering is
> correct.
> But for the rest of the payload, there's no need with OMPI's datatype
> engine. It's just more payload for no gain.
>
> Brian
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-- 
Jeff Squyres
Cisco Systems