dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

I suspect the problem is I don't have MTL4 installed on my desktop so
it defaults to uBlas for me. I don't have time to check now but will
check later. So, don't trust my results for MTL4 just yet.

We should probably issue an error when the backend is not available.

-- 
Anders


On Fri, Aug 08, 2008 at 10:14:33AM +0100, Garth N. Wells wrote:
> 
> 
> Anders Logg wrote:
> > 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.
> > 
> 
> We're cheating a bit at the moment. MLT4 needs to know the maximum 
> number on non-zeroes on any row. We're just guessing this for now.
> 
> Currently, MTLSparsityPattern::insert(..) is empty. If you look at my 
> benchmark results, the cost of building the MTLSparsityPattern is 
> negligible, but in yours and Ilmar's it's comparable to the cost of 
> building the sparsity pattern for uBLAS and PETSc. I have no idea what's 
> going on. I thought that the overhead was in SparsityPattern::insert(), 
> which is what my results indicate, whereas yours indicate that the 
> overhead is considerable in SparsityPatternBuilder.
> 
> > I can fix this later today if you don't fix it before.
> >
> 
> Let's leave it as id for now.
> 
> >> 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.
> >
> 
> The only change I made was to SparsityPattern, which seems to have given 
> you a bigger speed-up than it did me.
> 
> Garth
> 
> > 
> > 
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