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From: David Abrahams (dave_at_[hidden])
Date: 2005-11-24 08:07:27

"Peter Dimov" <pdimov_at_[hidden]> writes:

> I just want to note that contiguous arrays of double are handled
> equally well by either approach under discussion;

There are at least four approaches that could be considered "under
discussion" right now: Matthias' original proposal, Robert's
counter-proposal, our new proposal, and what you just proposed.

If your proposal handles some cases just as well as Matthias'
proposal, it's no coincidence: those proposals have crucial elements
in common. However, the elements those two proposals have in common
are the same ones that raised the strongest objections from Robert, so
we're trying to examine a less intrusive design for now.

> an mpi_archive will obviously include an overload for double[]. I
> was interested in the POD case. A large array of 3x3 matrices
> wrapped in matrix3x3 structs would probably be a good example that
> illustrates your point (c) above. (a) and (b) can be avoided by
> issuing multiple MPI_Send calls for non-optimized sequence writes.

As Matthias has pointed out, that has unacceptable performance costs.

Dave Abrahams
Boost Consulting

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