Hi Dominik,

I'm still packaging it (no stable copr build yet. I'm using https://copr.fedorainfracloud.org/coprs/talcite/qcint/ and https://copr.fedorainfracloud.org/coprs/talcite/libcint/), but it essentially calculates gaussian integrals for quantum chemistry software. It does something similar to Libint, except it uses a different algorithm. It's a part of a broader push on my part to have PySCF included into the repos, so I can finally get HORTON into there (also quantum chemistry packages).

And you're correct, it's almost inconceivable that someone would calculate on such old hardware. The jobs are rather computationally intensive (bordering on HPC).

Would it be safe just to go with the ExclusiveArch/ExcludeArch route then?

Thanks!

Matt

On Tue, 19 Jul 2016 at 00:38 Dominik 'Rathann' Mierzejewski <dominik@greysector.net> wrote:

Hello, Matt.

On Tuesday, 19 July 2016 at 00:06, Matthew Chan wrote:
> I'm currently packaging a libraries that are nearly identical, except one
> version is sse3 optimized, and the other is not. (license also changes to
> GPL from BSD). The performance difference is significant.
>
> What is the correct way to handle this? They both provide the same libraries
> and headers. Should I use an ExclusiveArch: x86_64 on the sse3 version, and
> an ExcludeArch: x86_64 on the unoptimized version? Or perhaps even use a
> conflicts? (Assuming there are x86_64 processors that don't support SSE3?
> SSE3 seems to have been introduced with Pentium 4 Prescott)

In theory, the code shipped in Fedora should work on any i686-class CPU
for x86 32bit builds and any x86_64 CPU. So if you want to enable any
kind of SIMD unconditionally, you can only rely on SSE2 presence in
x86_64 ABI. Anything else should be detected and used at runtime only.

Having said that, it's unlikely that someone is using your particular
package on such old hardware. What package are you talking about,
specifically?

There was a similar question in the devel list a couple of months back,
but with no replies:
https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/message/ZAHW6LT6VXFRD4LIT5NLLTZ72W2E24DW/

Regards,
Dominik
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