On Wed, Feb 13, 2013 at 1:27 PM, Roy Stogner <royst...@ices.utexas.edu>wrote:
>
> On Wed, 13 Feb 2013, Cody Permann wrote:
>
> So I'd be happy to work on this unless someone else wants to
>> volunteer. Clearly we'll need a pack this data up since the strings
>> will be variable length as we send this over the wire. I might need
>> a little guidance as to where or how this can be done. I looked at
>> the mesh_broadcast routine and can't immediately see where all of
>> the boundary_info data is sent. I'm missing something here...
>>
>
> The trick is that boundary info is packed up along with the elements
> and nodes it applies to. See parallel_elem.C and parallel_node.C for
> the implementation.
> We don't want every processor to know about every
> boundary id, only for every id on its own part of the boundary.
>
> I don't think this'll be what we want to do for those maps you added,
> though.
Hmm, so which is it? If you don't want ids everywhere, why would you want
strings everywhere?
> Those ought to be serialized, right? It would save a little
> memory but add a lot of communication if we tried to have each rank
> only store labels corresponding to boundary ids that had some support
> on that rank's partition.
>
Ah, so we have to decide on which trade-off we want...
>
> I'd love to add Parallel::pack/unpack/etc. implementations for
> std::pair and std::string.
Then you'd be able to broadcast each whole
> map with a single function call.
std::string for sure, but std::pair? Why not add an implementation for
std::map that just send pairs of vectors? I'm sure there are lots of
trade-offs for all of these designs.
> I'm not sure when I'd find time to
> get to it, though, so if you definitely want it before March you'll
> have to do it mostly yourself; ping me with any questions.
>
I guess we'll see - I don't know if we need this right now or not. We have
a huge backlog all the time so we just have to decide what gets done and
what doesn't, I'm sure you know the feeling.
Cody
> ---
> Roy
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