Re: [PATCH 3/3] core: convert build-time USE_NSEC into runtime core.useNanosec

On Fri, Aug 07, 2026 at 02:17:39PM -0700, Junio C Hamano wrote:
> "D. Ben Knoble" <[email protected]> writes:
> 
> > Racy Git problems persist today, manifesting themselves in the
> > performance of commands like "git diff" in new worktrees [1]. We have
> > long had a build knob "USE_NSEC" to tell Git to use in-core nanosecond
> > precision when available, which mitigates most if not all racy issues,
> > but most builds we know about it don't use it. In part, that's because
> > someone distributing Git can't safely enable it at compile-time if they
> > don't know exactly what platforms their distribution will be used on.
> >
> > [1]: https://lore.kernel.org/git/CALnO6CADMJSixqYvL1Yo8qKX5rWhKQ+2OoSEuPUh-yoeK9TseQ@mail.gmail.com
> >
> > These days, most platforms are likely to be safe for the USE_NSEC code.
> > Regardless, we want to give users the ability to benefit from it. This
> > requires exposing the compile-time gated code as a runtime option.
> >
> > In addition, update the Racy Git documentation and other mentions of
> > USE_NSEC in the code.
> >
> > Best-viewed-with: --ignore-space-change
> 
> Don't do this.  It probably is helpful to have something like that
> below the three-dash lines, though.

Including this hint in the commit message could be useful for anyone
who stumbles upon this commit in a couple of months or years time.
Whether it should be a trailer or not is another question.