[Mageia-dev] Packages not rebuilt since Mageia 1

[eatdirt]

On 26/03/13 15:24, Pascal Terjan wrote:
> There are 26 packages.
>
> atlas

I think, and unless someone complains, this one should be dropped. Atlas 
is supposed to provice fast routines already provided by blas and lapack 
(that we have), but:

http://math-atlas.sourceforge.net/atlas_install/node27.html

says:

"Many users ask how ATLAS can be used to build libraries that will run 
on all x86 platforms. In general, this is a bad idea: ATLAS gets its 
speed by specializing for particular platforms, so the more generic a 
library is the less performance it will achieve!"

and this is what we are doing. We even compile it with sseX options 
which is soon worse than doing nothing:

"
Never use these libraries unless this portability is absolutely 
required. They must use portable settings for blocking, for instance, 
which will mean that on many platforms they will use only a fraction of 
the actual cache, causing large performance drops. Even worse, peak 
performance may by reduced by as much as factor of 8, due to not using 
the proper ISA extension. The most portable ISA uses only the x87 unit, 
which has a much lower peak rate on most modern machines (eg., an Intel 
sandy bridge can do 16 flops/cycle using AVX in single precision, but 
only 8 flops/cycle if using SSE, and only 2 flops/cycle using the x87 unit).
"


Cheers,
Chris,