Re: [PATCH 0/2] Make tunable a default feature

[Siddhesh Poyarekar <siddhesh@gotplt.org>]

On 2023-03-13 15:06, Adhemerval Zanella wrote:
> It is enabled as default since 2.26, some features option require it
> (such as hwcap mask, huge pages support, and lock elisition tuning),
> and assuming its support also simplifies the build permutation.

from a historical perspective, there was not just the question of 
enabling tunables but also providing multiple ways to read tunables, 
each having its own parser.  That is why there's a 'valstring' as an 
option for --enable-tunables.

Over the years there haven't really been any other ideas to read 
tunables.  There's the idea of systemwide tunables through, e.g. 
ld.so.conf that we'd like to have at some point, but that is more 
effective alongside valstring than as an either-or feature.

There's also conceivably a use case for having only systemwide tunables 
without any valstring override but maybe that should get supported when 
it's actually needed by someone.  So in summary, I'm not aware of 
anybody using --disable-tunables, so I'm not opposed to removing the 
configure flag altogether and simplifying the code.  Hopefully if 
someone is using it they'll come forward before this patchset gets accepted.

Thanks,
Sid