dolfin team mailing list archive

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

A Navaei wrote:
> 2009/3/23 Garth N. Wells <gnw20@xxxxxxxxx>:
> > A Navaei wrote:
> > > The success of MTL4 based on generic meta-programming, arises the
> > > question about re-visiting the efficiency of code-generation
> > > approaches, including FFC. Given that FEM can particularly benefit
> > > from major meta-programming characteristics, namely static
> > > polymorphism and loop unrolling, MTL4 demonstrates that the
> > > code-generation part can be much more efficiently replaced by inlining
> > > performed at compile-time.
> > What FFC and other code generators do is a form of metaprogramming, so I
> > don't see what point you're trying to make.
>
> As mentioned above, we are talking about compile-time implicit inline
> code generation which is opposed to explicit code generation as done
> by FFC -- refer to MTL publications.

No, you have addressed meta-programming which is the generation of code. 
FFC does employ loop unrolling but it does not use static polymorphism. 
There is no fundamental reason why it could not also use static 
polymorphism (i.e. generate templated classes and functions).

MTL4 does do some very neat things, and the performance for a number of 
operations is very impressive. However, if you look at the code you will 
see that for relatively simple operations it, and uBLAS, are very 
sophisticated. Advocating such an approach for differential equations 
without a proof of concept does not demonstrate an appreciation of the 
complexity of differential equations and variational methods over basic 
linear algebra operations.

Garth



> -Ali
>
> > Garth
> >
> > > Without having a concrete meta-programming implementation, it may be
> > > impossible to predict how much performance one would gain compared to
> > > FFC. However, MTL4 has been reported to be many times faster than
> > > code-generation means such as ATLAS.
> > >
> > > Based on this, are there any specific benefits in FFC code-generation
> > > which may not be covered by meta-programming?
> > >
> > >
> > > -Ali
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