linux-kernel - Re: [PATCH] compiler/gcc: Make asm() templates asm __inline_

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Message-ID: <CAFULd4ZZ6rjG=LTQX6hsrqp6BQ5XcRW7kQ_rzHKrOxKCu51=sw@mail.gmail.com>
Date: Thu, 20 Mar 2025 11:30:04 +0100
From: Uros Bizjak <ubizjak@...il.com>
To: Ingo Molnar <mingo@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>, "H. Peter Anvin" <hpa@...or.com>, 
	linux-kernel@...r.kernel.org, Juergen Gross <jgross@...e.com>, 
	Stefano Stabellini <sstabellini@...nel.org>, "Ahmed S . Darwish" <darwi@...utronix.de>, 
	Andrew Cooper <andrew.cooper3@...rix.com>, John Ogness <john.ogness@...utronix.de>, 
	Peter Zijlstra <peterz@...radead.org>, Borislav Petkov <bp@...en8.de>, 
	Thomas Gleixner <tglx@...utronix.de>, Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH] compiler/gcc: Make asm() templates asm __inline__() by default

On Thu, Mar 20, 2025 at 9:59 AM Ingo Molnar <mingo@...nel.org> wrote:
>
>
> * Uros Bizjak <ubizjak@...il.com> wrote:
>
> > > > > I haven't looked at code generation much yet, but text size changes are
> > > > > minimal:
> > > > >
> > > > >       text         data     bss      dec            hex filename
> > > > >   29429076      7931870 1401196 38762142        24f769e vmlinux.before
> > > > >   29429631      7931870 1401200 38762701        24f78cd vmlinux.after
> > > > >
> > > > > Which is promising, assuming I haven't messed up anywhere.
> > > >
> > > > Please use bloat-o-meter, it is more precise.
> > >
> > > Here's the bloat-o-meter output between vanilla and patched vmlinux:
> >
> > [...]
> >
> > > A lot fewer functions are affected than I expected from such a
> > > large-scope change.
> >
> > Interestingly, I got *many* more changes just from converting atomic
> > locking functions to asm_inline, as reported in [1].
> >
> > [1] https://lore.kernel.org/lkml/CAFULd4YBcG45bigHBox2pu+To+Y5BzbRxG+pUr42AVOWSnfKsg@mail.gmail.com/
>
> Have you used a pristine x86-64 defconfig for your build tests?

Yes, it was vanilla x86-64 defconfig, but in -tip tree.

> Could you perhaps check my patch against your patch in your build
> environment and figure out why there's such unexpected differences?
>
> As you noted my patch should be a blunt-instrument superset of your
> changes so if then it should affect *more* functions, not fewer.

Yes, I'll try this experiment.

Thanks,
Uros.