Re: [PATCH 00/23] kbuild: significantly speed up kernel builds

[Lorenzo Stoakes (ARM)]

On Wed, Sep 09, 2026 at 03:09:10PM -0700, Nick Desaulniers wrote:
> On Wed, Sep 9, 2026 at 7:17 AM Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx> wrote:
> >
> > On Tue, Sep 08, 2026 at 02:06:18PM -0700, Nick Desaulniers wrote:
> > > It would be cool if your LLM could generate any visualizations of
> > > what's going on during a build? Seeing what's serial vs parallelized
> > > in perhaps useful. Particularly when you can compare the before vs
> > > after.
> >
> > Great idea!
> >
> > I asked it to do exactly that, attached. Came out quite nice and sums it up
> > nicely :)
> >
> > It also provided an ASCII version:
>
> unreadable, but the pictures you attached are worth a thousand words.

:) Yeah I didn't think the ASCII was amazing either but fun that it tried ;) and
yeah I was surprised at how nice the graphic came out...!

> Particularly exciting are the speed ups to the usual edit+compile+run
> loop.

Yes! I never really expected that out of this!

I mean I didn't think there'd be such a big speed up in general, though I
expected at least to shave off a big chunk of the delta between compile + full
build on a defconfig clean build.

But the incremental/noop build improvements are really important to day-to-day
use.

>
> For the blue graph (the top one, first), any idea what that dip in the
> middle is? That's always what annoyed me.

That's ld -r of vmlinux.o, then modpost and objtool which are critical path
blockers on the rest of the build.

Before the series that was 23 seconds for allmodconfig on the threadripper, now
7s :)

There's still more objtool stuff that could be done that I opted not to do yet,
it takes 6s to run so dominating.

> --
> Thanks,
> ~Nick Desaulniers

--
Cheers, Lorenzo