ffc team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Sat, Sep 06, 2008 at 11:12:17PM +0200, Kristian Oelgaard wrote:
> Quoting Anders Logg <logg@xxxxxxxxx>:
> 
> > On Sat, Sep 06, 2008 at 09:23:39PM +0100, Garth N. Wells wrote:
> > > FFC wrote:
> > > > One or more new changesets pushed to the primary ffc repository.
> > > > A short summary of the last three changesets is included below.
> > > > 
> > > > changeset:   1191:4129f43a04429e70de6383212ace548ca0fb7872
> > > > tag:         tip
> > > > user:        "Kristian Oelgaard <k.b.oelgaard@xxxxxxxxxx>"
> > > > date:        Sat Sep 06 21:31:23 2008 +0200
> > > > files:      
> > src/ffc/compiler/codegeneration/quadrature/quadraturegenerator.py
> > > > description:
> > > > Added code to output number of operations needed to compute the element
> > tensor (for quadrature representation).
> > > >
> > > 
> > > Is this the number of flops inside the tabulate_tensor function, or is 
> > > it related to FFC operations?
> 
> It is a count of all '*' and '+' operations on the RHS of all terms inside the
> IP loop. So it's an approximation of the number of flops needed to tabulate the
> element tensor. Anything that goes on before this loop is not taken into
> account, but for complex forms this is insignificant anyway.
>  
> > > Garth
> > 
> > This should be fairly easy to add for the tensor representation as
> > well, at least the number of flops to do the tensor contraction, so
> > we can use this to decide which representation to use.
> 
> But you want to decide this before generating the code? Or do you suggest
> compiling the code with both strategies and see which one produces the 'optimal'
> code?
>  
> > We may then set the default representation to "auto" which chooses
> > the correct strategy.
> 
> For this you definitely want some a priori estimation of the operation count.

Yes, I mean before the code is generated. Is that possible to get?

-- 
Anders

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