linux-kernel - Re: [PATCH v2 4/4] Make finish_task_switch and its subfuncs inline in context switching

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Message-ID: <20251109113533.GB2545891@noisy.programming.kicks-ass.net>
Date: Sun, 9 Nov 2025 12:35:33 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Xie Yuanbin <qq570070308@...il.com>
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Subject: Re: [PATCH v2 4/4] Make finish_task_switch and its subfuncs inline
 in context switching

On Sun, Nov 09, 2025 at 01:23:46AM +0800, Xie Yuanbin wrote:
> `finish_task_switch` is a hot path in context switching, and due to
> possible mitigations inside switch_mm, performance here is greatly
> affected by function calls and branch jumps. Make it inline to optimize
> the performance.
> 
> After `finish_task_switch` is changed to an inline function, the number of
> calls to the subfunctions (called by `finish_task_switch`) increases in
> this translation unit due to the inline expansion of `finish_task_switch`.
> Due to compiler optimization strategies, these functions may transition
> from inline functions to non inline functions, which can actually lead to
> performance degradation.
> 
> Make the subfunctions of finish_task_stwitch inline to prevent
> degradation.

Yeah, try again without that _ainline garbage.