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

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Message-ID: <Z9vY8Bm1Wv1vkqNO@gmail.com>
Date: Thu, 20 Mar 2025 09:59:28 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Uros Bizjak <ubizjak@...il.com>
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


* 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?

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.

Thanks,

	Ingo