dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Thu, Aug 07, 2008 at 10:32:56PM +0100, Garth N. Wells wrote:
> Something I don't understand is the time for creating the sparsity 
> pattern for MTL4 when it involves no operations?

MTL4Factory still returns a sparsity pattern. I wasn't aware that MTL4
didn't need one. MT4Factory should return 0 in createPattern() and
MTL4SparsityPattern can then be removed.

I can fix this later today if you don't fix it before.

> Why is uBLAS now faster than before (relative)?

I didn't notice. I might have made an apt-get upgrade in between.
I don't think anything has changed for uBlas in the code.

-- 
Anders


> Garth
> 
> Anders Logg wrote:
> > I have made some changes to allow a backend to notify that it does not
> > need to be initialized by a sparsity pattern. If the factory function
> > createSparsityPattern() returns 0, then the assembler will not build
> > the sparsity pattern.
> > 
> > I have tried this for the STL backend (earlier called AssemblyMatrix).
> > No sparsity pattern is computed and no preallocation is made, just
> > inserting directly into the vector of vectors using a linear search
> > and this gives very good speedups, see here:
> > 
> >   http://www.fenics.org/wiki/Benchmark
> > 
> > STL is 36% faster than all other backends for the NS testcase.
> > 
> > It is also about just as fast as the other backends for the assembly
> > step ("Assemble cells") even if no preallocation is made.
> > 
> > 
> > 
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