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List:       kde-kimageshop
Subject:    Re: OpenMP and krita
From:       Tom Burdick <tburdi1 () uic ! edu>
Date:       2007-05-17 15:03:46
Message-ID: 200705171003.46650.tburdi1 () uic ! edu
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Loading the SIMD registers shouldn't be too costly if the data is already 
pre-aligned with the right instrinsic datatype macros right?
as in movaps instead of movups. Been busy with school and robot project... so 
sorry for the instrusion here.

-Tom


On Thursday 17 May 2007 09:36:41 am Cyrille Berger wrote:
> On Thursday 17 May 2007, Boudewijn Rempt wrote:
> > Yes, that should be cool. Does OpenMP also use MMX and similar where
> > possible?
>
> no, it's not related :)
>
> > Because that's where I see the biggest benefit for compositing.
>
> Well the benefit of SIMD instructions is around 40% and 50% maximum (due to
> the cost of loading in the SIMD registers). While multithreading can reduce
> the CPU cost to a maximum 1/N (with N the number of processor). And some
> composite operation doesn't benefit from SIMD at all, at least that's what
> my experiments show, and it seems to be confirmed by the gimp source code
> ;)
>
> Anyway it needs experimenting, I am still working on SIMD library for Krita
> 2 :)


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