[Pkg-scicomp-devel] Bug#578052: Bug#578052: [atlas] providing >20 separate optimized library packages is insane

[Fabian Greffrath]

Am 16.04.2010 14:45, schrieb Sylvestre Ledru:
> Well, some people do not agree on this.
> I think it is important to let the user select the appropriate
> optimisation for his computer.

Yes, but since by default only the standard non-optimized library 
packages get installed, it will always require manual intervention to 
actually make use of optimizations. If you let the linker select the 
appropriate library it is the other way round: You always benefit from 
optimizations, unless you explicitely prevent it.

> I believe that a user looking for performances on tool based on BLAS
> implementation (R, Scilab, Code Saturne, etc) is aware that it is
> related to the CPU they have.

OK, a skilled user may be expected to know details about his computer 
architecture. But does he also necessarily have to know about Debian's 
update-alternatives mechanism and how to use it to actually make use 
of the special libraries?

> I noticed your message on my blog. I didn't have time to investigate it:
> I am currently more focused on build issues on some architectures but I
> have it in mind.

Yes, of course, this bug was merely meant as a reminder. ;)

> However, if I understand correctly, this would mean that I would have to
> ship all libraries into a single package or to add some Depends on the
> base package, isn't it ?

I'd prefer to put them all into a single package and leave the other 
packages as transitional ones simply depending on the new 
"all-inclusive" package.

> An atlas package is almost 5M. For example, under x86, we have 5
> optimized packages. This would increase by 5 time the install of Atlas.

Yes, unfortunately. Another possibility would be to not provide such 
fine-grained optimizations by simply reducing the number of optimized 
libraries.

> The separation has been in Debian for a very long time (more than 10
> years) and it is the first strong complain that I see about that (I know
> it is not an argument for not doing it).

Oh, really? I didn't know! From reading your blog post I was under the 
impression that the separation was also another new feature that you 
just introduced with the upload of 3.8.3. I must have misunderstood 
it. However, as you noticed yourself, tradition is not a reason 
against improvement. ;)

Cheers,
Fabian


-- 
Dipl.-Phys. Fabian Greffrath

Ruhr-Universität Bochum
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