linux-kernel - Re: [PATCH] entry: always inline local_irq_{enable,disable}_exit_to

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Message-ID: <20251205105123.GS2528459@noisy.programming.kicks-ass.net>
Date: Fri, 5 Dec 2025 11:51:23 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Eric Dumazet <edumazet@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Andy Lutomirski <luto@...nel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH] entry: always inline
 local_irq_{enable,disable}_exit_to_user()

On Thu, Dec 04, 2025 at 03:31:27PM +0000, Eric Dumazet wrote:
> clang needs __always_inline instead of inline, even for tiny helpers.
> 
> This saves some cycles in system call fast path, and saves 195 bytes
> on x86_64 build:
> 
> $ size vmlinux.before vmlinux.after
>    text	   data	    bss	    dec	    hex	filename
> 34652814	22291961	5875180	62819955	3be8e73	vmlinux.before
> 34652619	22291961	5875180	62819760	3be8db0	vmlinux.after
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Yeah, sometimes these inline heuristics drive me mad. I've picked up
this and the rseq one. I'll do something with them after rc1.