From: Masahiro Yamada <masahiroy@kernel.org>
To: David Laight <David.Laight@aculab.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>, Jakub Kicinski <kuba@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH net v3] net: Force inlining of checksum functions in net/checksum.h
Date: Fri, 18 Feb 2022 01:17:27 +0900 [thread overview]
Message-ID: <CAK7LNASWTJ-ax9u5yOwHV9vHCBAcQTazV-oXtqVFVFedOA0Eqw@mail.gmail.com> (raw)
In-Reply-To: <3c2b682a7d804b5e8749428b50342c82@AcuMS.aculab.com>
On Fri, Feb 18, 2022 at 12:15 AM David Laight <David.Laight@aculab.com> wrote:
>
> From: Christophe Leroy
> > Sent: 17 February 2022 14:55
> >
> > Le 17/02/2022 à 15:50, Christophe Leroy a écrit :
> > > Adding Ingo, Andrew and Nick as they were involved in the subjet,
> > >
> > > Le 17/02/2022 à 14:36, David Laight a écrit :
> > >> From: Christophe Leroy
> > >>> Sent: 17 February 2022 12:19
> > >>>
> > >>> All functions defined as static inline in net/checksum.h are
> > >>> meant to be inlined for performance reason.
> > >>>
> > >>> But since commit ac7c3e4ff401 ("compiler: enable
> > >>> CONFIG_OPTIMIZE_INLINING forcibly") the compiler is allowed to
> > >>> uninline functions when it wants.
> > >>>
> > >>> Fair enough in the general case, but for tiny performance critical
> > >>> checksum helpers that's counter-productive.
> > >>
> > >> There isn't a real justification for allowing the compiler
> > >> to 'not inline' functions in that commit.
> > >
> > > Do you mean that the two following commits should be reverted:
> > >
> > > - 889b3c1245de ("compiler: remove CONFIG_OPTIMIZE_INLINING entirely")
> > > - 4c4e276f6491 ("net: Force inlining of checksum functions in
> > > net/checksum.h")
> >
> > Of course not the above one (copy/paste error), but:
> > - ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING forcibly")
>
> That's the one I looked at.
No. Not that one.
The commit you presumably want to revert is:
a771f2b82aa2 ("[PATCH] Add a section about inlining to
Documentation/CodingStyle")
This is now referred to as "__always_inline disease", though.
CONFIG_OPTIMIZE_INLINING has 14 years of history for x86.
See commit 60a3cdd06394 ("x86: add optimized inlining").
We always give gcc freedom to not inline functions marked as inline.
--
Best Regards
Masahiro Yamada
next prev parent reply other threads:[~2022-02-17 16:30 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-17 12:19 [PATCH net v3] net: Force inlining of checksum functions in net/checksum.h Christophe Leroy
2022-02-17 13:36 ` David Laight
2022-02-17 14:50 ` Christophe Leroy
2022-02-17 14:55 ` Christophe Leroy
2022-02-17 15:15 ` David Laight
2022-02-17 16:17 ` Masahiro Yamada [this message]
2022-02-17 16:49 ` David Laight
2022-02-17 17:27 ` Masahiro Yamada
2022-02-17 18:07 ` Segher Boessenkool
2022-02-18 1:35 ` Masahiro Yamada
2022-02-18 12:12 ` Segher Boessenkool
2022-02-18 16:29 ` Stephen Hemminger
2022-02-18 16:44 ` Segher Boessenkool
2022-02-18 8:41 ` David Laight
2022-02-17 15:42 ` Joe Perches
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