From: Ingo Molnar <mingo@kernel.org>
To: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Thomas Graf <tgraf@suug.ch>,
Peter Zijlstra <peterz@infradead.org>,
David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] force inlining of some byteswap operations
Date: Fri, 5 Feb 2016 08:28:12 +0100 [thread overview]
Message-ID: <20160205072812.GA28210@gmail.com> (raw)
In-Reply-To: <1454615136-32308-2-git-send-email-dvlasenk@redhat.com>
* Denys Vlasenko <dvlasenk@redhat.com> wrote:
> Sometimes gcc mysteriously doesn't inline
> very small functions we expect to be inlined. See
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122
>
> With this .config:
> http://busybox.net/~vda/kernel_config_OPTIMIZE_INLINING_and_Os,
> the following functions get deinlined many times.
> Examples of disassembly:
>
> <get_unaligned_be16> (12 copies, 51 calls):
> 66 8b 07 mov (%rdi),%ax
> 55 push %rbp
> 48 89 e5 mov %rsp,%rbp
> 86 e0 xchg %ah,%al
> 5d pop %rbp
> c3 retq
>
> <get_unaligned_be32> (12 copies, 135 calls):
> 8b 07 mov (%rdi),%eax
> 55 push %rbp
> 48 89 e5 mov %rsp,%rbp
> 0f c8 bswap %eax
> 5d pop %rbp
> c3 retq
>
> <get_unaligned_be64> (2 copies, 20 calls):
> 48 8b 07 mov (%rdi),%rax
> 55 push %rbp
> 48 89 e5 mov %rsp,%rbp
> 48 0f c8 bswap %rax
> 5d pop %rbp
> c3 retq
>
> <__swab16p> (16 copies, 146 calls):
> 55 push %rbp
> 89 f8 mov %edi,%eax
> 86 e0 xchg %ah,%al
> 48 89 e5 mov %rsp,%rbp
> 5d pop %rbp
> c3 retq
>
> <__swab32p> (43 copies, ~560 calls):
> 55 push %rbp
> 89 f8 mov %edi,%eax
> 0f c8 bswap %eax
> 48 89 e5 mov %rsp,%rbp
> 5d pop %rbp
> c3 retq
>
> <__swab64p> (21 copies, 119 calls):
> 55 push %rbp
> 48 89 f8 mov %rdi,%rax
> 48 0f c8 bswap %rax
> 48 89 e5 mov %rsp,%rbp
> 5d pop %rbp
> c3 retq
>
> <__swab32s> (6 copies, 47 calls):
> 8b 07 mov (%rdi),%eax
> 55 push %rbp
> 48 89 e5 mov %rsp,%rbp
> 0f c8 bswap %eax
> 89 07 mov %eax,(%rdi)
> 5d pop %rbp
> c3 retq
>
> This patch fixes this via s/inline/__always_inline/.
> Code size decrease after the patch is ~4.5k:
>
> text data bss dec hex filename
> 92202377 20826112 36417536 149446025 8e85d89 vmlinux
> 92197848 20826112 36417536 149441496 8e84bd8 vmlinux5_swap_after
Acked-by: Ingo Molnar <mingo@kernel.org>
Thanks,
Ingo
next prev parent reply other threads:[~2016-02-05 7:28 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-04 19:45 [PATCH] asm-generic: force inlining of some atomic_long operations Denys Vlasenko
2016-02-04 19:45 ` [PATCH] force inlining of some byteswap operations Denys Vlasenko
2016-02-05 7:28 ` Ingo Molnar [this message]
2016-04-13 3:36 ` This patch triggers a bad gcc bug (was Re: [PATCH] force inlining of some byteswap operations) Josh Poimboeuf
2016-04-13 12:12 ` Denys Vlasenko
2016-04-13 12:36 ` Josh Poimboeuf
2016-04-13 15:15 ` Josh Poimboeuf
2016-04-13 16:55 ` James Bottomley
2016-04-13 17:10 ` Josh Poimboeuf
2016-04-14 15:29 ` Denys Vlasenko
2016-04-14 15:57 ` Josh Poimboeuf
2016-04-14 17:09 ` Denys Vlasenko
2016-04-15 5:45 ` Ingo Molnar
2016-04-15 13:47 ` Josh Poimboeuf
2016-04-15 22:20 ` Josh Poimboeuf
2016-04-16 9:03 ` Ingo Molnar
2016-04-18 13:39 ` Josh Poimboeuf
2016-04-18 14:07 ` Arnd Bergmann
2016-04-18 14:12 ` Josh Poimboeuf
2016-04-18 14:21 ` Arnd Bergmann
2016-04-19 8:52 ` Ingo Molnar
2016-04-19 13:56 ` [PATCH] scsi: fc: force inlining of wwn conversion functions Josh Poimboeuf
2016-04-22 23:17 ` Quinn Tran
2016-04-25 16:07 ` Josh Poimboeuf
2016-04-26 2:40 ` Martin K. Petersen
2016-04-26 3:37 ` James Bottomley
2016-04-26 7:22 ` Arnd Bergmann
2016-04-26 8:35 ` Christoph Hellwig
2016-04-26 10:05 ` Arnd Bergmann
2016-04-26 13:06 ` Martin K. Petersen
2016-04-26 15:58 ` Arnd Bergmann
2016-04-26 22:36 ` James Bottomley
2016-04-27 0:44 ` Martin K. Petersen
2016-04-27 11:05 ` Martin Jambor
2016-04-27 21:34 ` Arnd Bergmann
2016-04-28 14:58 ` Chris Metcalf
2016-04-28 15:23 ` Arnd Bergmann
2016-04-28 15:48 ` Chris Metcalf
2016-04-27 22:00 ` [PATCH, RFT] byteswap: try to avoid __builtin_constant_p gcc bug Arnd Bergmann
2016-04-27 22:11 ` Josh Poimboeuf
2016-04-28 16:27 ` Quinn Tran
2016-04-16 7:42 ` This patch triggers a bad gcc bug (was Re: [PATCH] force inlining of some byteswap operations) Arnd Bergmann
2016-04-18 13:22 ` Josh Poimboeuf
2016-02-04 19:45 ` [PATCH] force inlining of unaligned byteswap operations Denys Vlasenko
2016-02-05 7:28 ` Ingo Molnar
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