linux-kernel - Re: [PATCH 1/1] arm/syscalls: mark syscall invocation as likely in invoke

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Message-ID: <aM1BSZV43DB_l5OU@willie-the-truck>
Date: Fri, 19 Sep 2025 12:40:57 +0100
From: Will Deacon <will@...nel.org>
To: Can Peng <pengcan@...inos.cn>
Cc: catalin.marinas@....com, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] arm/syscalls: mark syscall invocation as likely in
 invoke_syscall

On Fri, Sep 19, 2025 at 06:00:42PM +0800, Can Peng wrote:
> The invoke_syscall() function is overwhelmingly called for
> valid system call entries. Annotate the main path with likely()
> to help the compiler generate better branch prediction hints,
> reducing CPU pipeline stalls due to mispredictions.
> 
> This is a micro-optimization targeting syscall-heavy workloads.

Does it actually make a measurable difference?

Will