From: Segher Boessenkool <segher@kernel.crashing.org>
To: Rik van Riel <riel@surriel.com>
Cc: Xie Yuanbin <qq570070308@gmail.com>,
linux@armlinux.org.uk, mathieu.desnoyers@efficios.com,
paulmck@kernel.org, pjw@kernel.org, palmer@dabbelt.com,
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borntraeger@linux.ibm.com, svens@linux.ibm.com,
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Subject: Re: [PATCH 2/3] Provide and use an always inline version of finish_task_switch
Date: Sat, 25 Oct 2025 09:36:12 -0500 [thread overview]
Message-ID: <aPzgXBd34r2wVy8I@gate> (raw)
In-Reply-To: <18734a4944e47952b7ad3e10a36c902392bdaa91.camel@surriel.com>
On Fri, Oct 24, 2025 at 05:36:06PM -0400, Rik van Riel wrote:
> On Sat, 2025-10-25 at 02:35 +0800, Xie Yuanbin wrote:
> > finish_task_switch is called during context switching,
> > inlining it can bring some performance benefits.
> >
> > Add an always inline version `finish_task_switch_ainline` to be
> > called
> > during context switching, and keep the original version for being
> > called
> > elsewhere, so as to take into account the size impact.
>
> Does that actually work, or does the compiler
> still inline some of those "non-inlined" versions,
> anyway?
Of course the compiler does! That is part of the compiler's job after
all, to generate fast, efficient code!
The compiler will inline stuff when a) it *can*, mostly it has to have
the function body available; and b) it estimates it to be a win to
inline it. There is a whole bunch of heuristics for this. One of those
is that the always_inline attribute will do the utmost to get inlining
to happen.
(All that is assuming you have -finline-functions turned on, like you do
have at -O2).
Segher
next prev parent reply other threads:[~2025-10-25 14:38 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-24 18:26 [PATCH 0/3] Optimize code generation during context switching Xie Yuanbin
2025-10-24 18:26 ` [PATCH 1/3] Change enter_lazy_tlb to inline on x86 Xie Yuanbin
2025-10-24 20:14 ` Rik van Riel
2025-10-24 18:35 ` [PATCH 2/3] Provide and use an always inline version of finish_task_switch Xie Yuanbin
2025-10-24 18:35 ` [PATCH 3/3] Set the subfunctions called by finish_task_switch to be inline Xie Yuanbin
2025-10-24 19:44 ` Thomas Gleixner
2025-10-25 18:51 ` Xie Yuanbin
2025-10-24 21:36 ` [PATCH 2/3] Provide and use an always inline version of finish_task_switch Rik van Riel
2025-10-25 14:36 ` Segher Boessenkool [this message]
2025-10-25 17:37 ` [PATCH 0/3] Optimize code generation during context Xie Yuanbin
2025-10-29 10:26 ` David Hildenbrand
2025-10-30 15:04 ` Xie Yuanbin
2025-10-25 19:18 ` [PATCH 2/3] Provide and use an always inline version of finish_task_switch Xie Yuanbin
2025-10-25 12:26 ` [PATCH 0/3] Optimize code generation during context switching Peter Zijlstra
2025-10-25 18:20 ` [PATCH 0/3] Optimize code generation during context Xie Yuanbin
2025-10-27 15:21 ` Xie Yuanbin
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