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Subject: Re: [OMPI devel] matching code rewrite in OB1
From: Richard Graham (rlgraham_at_[hidden])
Date: 2007-12-13 20:04:21


Yes, should be a bit more clear. Need an independent way to verify that
data is matched
 in the correct order ­ sending this information as payload is one way to do
this. So,
 sending unique data in every message, and making sure that it arrives in
the user buffers
 in the expected order is a way to do this.

Rich

On 12/12/07 5:04 PM, "Jeff Squyres" <jsquyres_at_[hidden]> wrote:

> 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
>> > _______________________________________________
>> > devel mailing list
>> > devel_at_[hidden]
>> > http://www.open-mpi.org/mailman/listinfo.cgi/devel
>
>
> --
> Jeff Squyres
> Cisco Systems
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