Re: SIMDebian: Debian Partial Fork with Radical ISA Baseline

[Drew Parsons <dparsons@debian.org>]

On 2019-02-09 03:25, Mo Zhou wrote:
> Hi folks,
>
> For most programs the "-march=native" option is not expected to bring 
> any
> significant performance improvement. However for some scientific 
> applications
> this proposition doesn't hold. When I was creating the tensorflow 
> debian
> package, I observed a significant performance gap between generic code 
> and
> kabylake (Intel 7XXX Series) code[1].
...
> Generally speaking, in order to bump the ISA baseline for a given 
> package, one
> could add the -march=xxx flag to {C,CXX,F}FLAGS by modifying 
> debian/rules.
> However SIMDebian employes a more economic approach to this end: 
> forking
> dpkg[5] and injecting -march=xxx flag to the system default flag list. 
> With the
> resulting dpkg package, most debian packages could be rebuilt with 
> bumped ISA
> baseline without any code modification.


I think it would be more constructive to provide arch-specific packages 
for eigen/blas etc on amd64 which Conflict/Replace/Provide the standard 
packages.

That way a local administrator can choose to install them if they help 
improve performance.

Hacking dpkg itself for this purpose and forking an entire linux 
distribution is way too invasive and distracts from solving the actual 
problem.

Drew