From: Andrew Morton <akpm@linux-foundation.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm: Outline copy_overflow()
Date: Mon, 7 Feb 2022 12:40:02 -0800 [thread overview]
Message-ID: <20220207124002.edd04bf6d2abac8a01e35144@linux-foundation.org> (raw)
In-Reply-To: <b9a31b025e729394e7081257870f0a0e73355a04.1644229010.git.christophe.leroy@csgroup.eu>
On Mon, 7 Feb 2022 11:55:18 +0100 Christophe Leroy <christophe.leroy@csgroup.eu> wrote:
> While building a small config with CONFIG_CC_OPTIMISE_FOR_SIZE,
> I ended up with more than 50 times the following function in vmlinux:
>
> c00243bc <copy_overflow>:
> c00243bc: 94 21 ff f0 stwu r1,-16(r1)
> c00243c0: 7c 85 23 78 mr r5,r4
> c00243c4: 7c 64 1b 78 mr r4,r3
> c00243c8: 3c 60 c0 62 lis r3,-16286
> c00243cc: 7c 08 02 a6 mflr r0
> c00243d0: 38 63 5e e5 addi r3,r3,24293
> c00243d4: 90 01 00 14 stw r0,20(r1)
> c00243d8: 4b ff 82 45 bl c001c61c <__warn_printk>
> c00243dc: 0f e0 00 00 twui r0,0
> c00243e0: 80 01 00 14 lwz r0,20(r1)
> c00243e4: 38 21 00 10 addi r1,r1,16
> c00243e8: 7c 08 03 a6 mtlr r0
> c00243ec: 4e 80 00 20 blr
>
> That function being a non conditional warning on an error path,
> it is not worth inlining.
>
> Outline it.
"uninline" is the conventional term for this.
> This reduces the size of vmlinux by almost 4kbytes.
Did you consider uninlining check_copy_size() instead?
next prev parent reply other threads:[~2022-02-07 20:40 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-07 10:55 Christophe Leroy
2022-02-07 13:46 ` kernel test robot
2022-02-07 20:40 ` Andrew Morton [this message]
2022-02-08 19:04 ` Christophe Leroy
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