dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Jun 01, 2009 at 03:53:55PM +0100, Garth N. Wells wrote:
> 
> 
> 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.

That sounds good. I've added a comment to SparsityPattern so we don't
forget about it.

-- 
Anders

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