linux-kernel - Re: [PATCH v2 3/4] Provide the always inline version of some functions

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Message-ID: <20251110154301.1930-1-qq570070308@gmail.com>
Date: Mon, 10 Nov 2025 23:43:01 +0800
From: Xie Yuanbin <qq570070308@...il.com>
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Subject: Re: [PATCH v2 3/4] Provide the always inline version of some functions

On Sun, 09 Nov 2025 18:35:23 +0100, Arnd Bergmann wrote:
> You can mark the caller as __attribute__((flatten)) to force all
> functions to be inlined into that one if possible. I don't know
> if that would be helpful or desired here though.
Thanks, you made me aware of this attribute for the first time, it is
really a great attribute, and it has been already added to the kernel
public header. However, it's rarely used in the kernel, which I really
think is a pity.

Perhaps, I can try adding this attribute to some hot functions in
another patch. For this patch, I think this is sufficient. There are some
cold if branches inside `__schedule`, __flatten will inline the function
calls in this part of the code, which may cause some unexpected
performance degradation.

>     Arnd

Xie Yuanbin