Re: [PATCH v3 00/20] kbuild: significantly speed up kernel builds

[Lorenzo Stoakes (ARM)]

On Thu, Sep 17, 2026 at 10:15:26AM -0700, Linus Torvalds wrote:
> On Thu, 17 Sept 2026 at 09:06, Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx> wrote:
> >
> >                 == defconfig FULL build ==
> >
> >                         before    after     delta
> >                       ----------------------------------
> > Threadripper, gcc        32.5s    26.3s     -6.1s (-19%)
> > Threadripper, clang      34.5s    27.2s     -7.3s (-21%)
> > EPYC, gcc                28.7s    20.6s     -8.1s (-28%)
> > EPYC, clang              39.8s    32.2s     -7.6s (-19%)
> > M2, gcc                 519.3s   512.4s     -6.9s (-1%)
> > M2, clang               634.5s   569.4s    -65.1s (-10%)
>
> There's something odd going on with that M2 gcc build. Why is it such
> an odd duck?

Ugh dear lord I think the LLM somehow corrupted the numbers... Let me
re-run those myself locally and come back with the actual times!

(I didn't do an allmodconfig out of pure impatience but might take the time
to do that too)

>
>              Linus

--
Cheers, Lorenzo