[RFC] The nginx way of handling optimizations for hw architectures

[Sergey A. Osokin]

Hi Joe,

hope you're doing well.

I'm supporting nginx for FreeBSD ports tree for years and we usually don't
use '--with-cpu-opt' flag for the port/package build.  Also, this is the general
recommendation described on FreeBSD Porters Handbook to avoid to use opti-
misation flags from the third-party Makefiles, please see
https://www.freebsd.org/doc/en_US.ISO8859-1/books/porters-handbook/dads-cflags.html
for details.

Let me know if you have any questions.
Thanks.

--
Sergey Osokin

On Tue, Nov 19, 2019 at 01:01:03PM -0800, Joe Konno wrote:
> Hey all,
> 
> I'm requesting comment/input on how nginx would like to do architecture
> detection at build time as well as at run time. This is for the purposes
> of optimizing nginx for specific hardware (see my e-mail address for
> what specific hardware I hope to optimize for). ^_^
> 
> For build time, I see nginx has '--with-cpu-opt'. Does the community use
> that configure flag much (if at all)? I could see adding some host
> detection facilities. But, for OSes who build and/or package for
> multiple architectures, the limitations of such detection become
> immediately apparent.
> 
> Bear with me as I get architecture-specific, but for run time, I do see
> a core function using (the first leaf of) CPUID output to determine a
> cache line size. Other leaves of the CPUID instruction could be used, at
> run time /or/ configure/build time, to determine which optimized
> function(s) to use given the host CPU's capabilities.
> 
> There are a few ways to handle optimizations at the instruction set
> level, so I am looking for guidance on the "nginx way" of doing such
> things. Is there a line between what optimizations should be determined
> at build time? At run time? The Development Guide doesn't say much about
> this-- or I missed it-- so any hints/clues are appreciated.
> 
> ^_^
> 
> -- 
> Cheers
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