dolfin team mailing list archive

[Johan Hake <hake@xxxxxxxxx>]

On Monday 05 October 2009 11:35:09 Garth N. Wells wrote:
> Johan Hake wrote:
> > On Monday 05 October 2009 11:21:34 Anders Logg wrote:
> >> On Mon, Oct 05, 2009 at 09:33:48AM +0200, Johan Hake wrote:
> >>> Hello!
> >>>
> >>> The one reason (as I can recall) to include the Data class, for passing
> >>> of information to the former Function::eval method, was for future
> >>> thread safety.
> >>
> >> I don't remember but that may be one of the reasons. There were others.
> >
> > Ok.
> >
> >>> Previously we stored the Cell, and some other stuff, as a public
> >>> accessible member, before we called eval during assemble. This was not
> >>> thread safe.
> 
> It can be made thread-safe if Data has a copy constructor. I played with
>   parallelising the assembly loop using OpenMP, and to do that I needed
> to add a copy constructor to UFC since each thread needed its own UFC
> object.

Ok, but too much copying does not sound efficient?

Johan

> Garth
> 
> Instead we agreed on passing this data as argument, making
> 
> >>> it more thread safe.
> >>>
> >>> This might not be a big issue if we, when we implement support for
> >>> threads (whenever this happens...) let the local Data object be stored
> >>> in an indexed std::vector, and then keep the present eval interface.
> >>
> >> Sounds like it could work, but we'll see when get to that point. It
> >> doesn't matter for the current parallel implementation.
> >
> > Ok.
> >
> > Johan
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