dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Anders Logg wrote:
> On Mon, Jun 01, 2009 at 04:06:40PM +0200, DOLFIN wrote:
> > One or more new changesets pushed to the primary dolfin repository.
> > A short summary of the last three changesets is included below.
> >
> > changeset:   6245:30c1540b12097130e3ed48ed572819471c884a7b
> > tag:         tip
> > user:        "Garth N. Wells <gnw20@xxxxxxxxx>"
> > date:        Mon Jun 01 15:06:26 2009 +0100
> > files:       dolfin/la/EpetraSparsityPattern.cpp dolfin/la/EpetraSparsityPattern.h dolfin/la/GenericSparsityPattern.h dolfin/la/SparsityPattern.cpp dolfin/la/SparsityPattern.h dolfin/la/uBLASMatrix.h
> > description:
> > Use std::set in SparsityPattern.
> >
> > Some performance issues seem to have been resolved with std::set.
> >
> > std::tr1::unsorted_set is faster, but requires some effort to sort. Sorting is only relevant to the uBLAS backend at this point.
>
> Building the sparsity pattern seems to be slightly faster, but
> deleting it takes significantly longer. The relative slowdown for that
> step is a factor 15-20.
>
> I was wondering why we used std::vector instead of std::set, but this
> might be the reason: It takes a *long* time to delete std::set. We
> should look for something else.

I recall set insertion also being dead slow, which is why I used 
std::vector with a homemade insert. Despite having programmed it, it 
took me a bit to understand what the code I wrote does which I why I 
tried set again.

We should try std::tr1::unsorted_set. It's faster for insertion but I 
don't know about the delete. We can cook something up to do the sort for 
uBLAS.

Garth

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