How user space applications can take advantage of CPU features

[Rabin Yasharzadehe]

I'm not much of an expert, but the first thing that comes to mind is the
binary size and speed.
If you only need to implement the code once, and have a single optimized
version, the output will be smaller, and probably a bit faster.





--
Rabin


On Fri, 20 Aug 2021 at 11:54, Lev Olshvang <levonshe at yandex.com> wrote:

> Morning people of the Linux !
>
> Recently I came to a question I do not know the answer to although I am
> with Linux for >20 years,
>
> I am talking about the CPU architecture features likes SIMD, SSE, AES, ...
>  and related gcc CPU architecture switches
> -maes, -msse3, -msse4 -mrdrand are examples of such gcc switches.
>
> I know that OPENSSL queries  CPU features in run-time and then selects
> precompiled functions that takes advantage of a specific feature.
>
> I think the kernel does the same
>
> So I begin to think that such compiler switches are good only to C
> functions which are written in a very specific way to allow gcc to
> recognize graphic or crypto processing patterns and generate the assembly
> in order to utilize those assem;y extensions.
> Otherwise those switches does nothing good.
>
> Please enlighten me on the issue.
>
> Be Healthy,
> Lev
> _______________________________________________
> Linux-il mailing list
> Linux-il at cs.huji.ac.il
> http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.cs.huji.ac.il/pipermail/linux-il/attachments/20210827/6bf8381b/attachment-0001.html>