linux-kernel - Re: [PATCH v6 0/4] entry: Move ret_from_fork() to C and inline syscall_exit_to_user

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Message-ID: <aA_5IGGvXqB7v_EA@ghost>
Date: Mon, 28 Apr 2025 14:54:40 -0700
From: Charlie Jenkins <charlie@...osinc.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Huacai Chen <chenhuacai@...nel.org>,
	WANG Xuerui <kernel@...0n.name>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Alexandre Ghiti <alexghiti@...osinc.com>,
	Arnd Bergmann <arnd@...db.de>, Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>, linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev
Subject: Re: [PATCH v6 0/4] entry: Move ret_from_fork() to C and inline
 syscall_exit_to_user_mode()

On Fri, Mar 21, 2025 at 10:22:36PM +0100, Thomas Gleixner wrote:
> On Thu, Mar 20 2025 at 10:29, Charlie Jenkins wrote:
> > Similar to commit 221a164035fd ("entry: Move
> > syscall_enter_from_user_mode() to header file"), move
> > syscall_exit_to_user_mode() to the header file as well.
> >
> > Testing was done with the byte-unixbench [1] syscall benchmark (which
> > calls getpid) and QEMU. On riscv I measured a 7.09246% improvement, on
> > x86 a 2.98843% improvement, on loongarch a 6.07954% improvement, and on
> > s390 a 11.1328% improvement.
> >
> > The Intel bot also reported "kernel test robot noticed a 1.9%
> > improvement of stress-ng.seek.ops_per_sec" [2]
> >
> > Since this is on QEMU, I know these numbers are not perfect, but they
> > show a trend of general improvement across all architectures that use
> > the generic entry code.
> 
> This looks sane now. I've bookmarked it as post-merge window material.

Has this been applied somewhere?

- Charlie

> 
> Thanks,
> 
>         tglx