From: Grant Coady <grant_lkml@dodo.com.au>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Antonio Vargas <windenntw@gmail.com>,
gcoady@gmail.com, Andrew Morton <akpm@osdl.org>,
Adrian Bunk <bunk@stusta.de>,
mingo@elte.hu, tim@physik3.uni-rostock.de, torvalds@osdl.org,
davej@redhat.com, linux-kernel@vger.kernel.org, mpm@selenic.com
Subject: Re: [patch 00/2] improve .text size on gcc 4.0 and newer compilers
Date: Tue, 03 Jan 2006 10:10:37 +1100 [thread overview]
Message-ID: <micjr1lipg2puqbtsocicc37vtfcjbu1jk@4ax.com> (raw)
In-Reply-To: <1136242584.2839.1.camel@laptopd505.fenrus.org>
On Mon, 02 Jan 2006 23:56:23 +0100, Arjan van de Ven <arjan@infradead.org> wrote:
>I proposed the following chunks:
>
>Adds a bit of text to Documentation/Codingstyle to state that
>inlining everything "just because" is a bad idea
>
>Signed-off-by: Arjan van de Ven <arjan@infradead.org>
>
>diff -purN linux-2.6.15-rc6/Documentation/CodingStyle linux-2.6.15-rc6-deinline/Documentation/CodingStyle
>--- linux-2.6.15-rc6/Documentation/CodingStyle 2005-10-28 02:02:08.000000000 +0200
>+++ linux-2.6.15-rc6-deinline/Documentation/CodingStyle 2005-12-30 13:31:13.000000000 +0100
>@@ -344,7 +344,7 @@ Remember: if another thread can find you
> have a reference count on it, you almost certainly have a bug.
>
>
>- Chapter 11: Macros, Enums, Inline functions and RTL
>+ Chapter 11: Macros, Enums and RTL
>
> Names of macros defining constants and labels in enums are capitalized.
>
>@@ -429,7 +429,35 @@ from void pointer to any other pointer t
> language.
>
>
>- Chapter 14: References
>+ Chapter 14: The inline disease
>+
>+There appears to be a common misperception that gcc has a magic "make me
>+faster" ricing option called "inline". While the use of inlines can be
^^^^^^--?? not sure what this is
>+appropriate (for example as a means of replacing macros, see Chapter 11), it
>+very often is not. Abundant use of the inline keyword leads to a much bigger
>+kernel, which in turn slows the system as a whole down, due to a bigger
>+icache footprint for the CPU and simply because there is less memory
>+available for the pagecache. Just think about it; a pagecache miss causes a
>+disk seek, which easily takes 5 miliseconds. There are a LOT of cpu cycles
>+that can go into these 5 miliseconds.
>+
>+A reasonable rule of thumb is to not put inline at functions that have more
>+than 3 lines of code in them. An exception to this rule are the cases where
>+a parameter is known to be a compiletime constant, and as a result of this
>+constantness you *know* the compiler will be able to optimize most of your
>+function away at compile time. For a good example of this later case, see
>+the kmalloc() inline function.
>+
>+Often people argue that adding inline to functions that are static and used
>+only once is always a win since there is no space tradeoff. While this is
>+technically correct, gcc is capable of inlining these automatically without
>+help, and the maintenance issue of removing the inline when a second user
>+appears outweighs the potential value of the hint that tells gcc to do
>+something it would have done anyway.
Seems sane, reasonable and mostly readable to me, thank you.
Grant.
next prev parent reply other threads:[~2006-01-02 23:10 UTC|newest]
Thread overview: 210+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-28 11:46 [patch 00/2] improve .text size on gcc 4.0 and newer compilers Ingo Molnar
2005-12-28 19:17 ` Linus Torvalds
2005-12-28 19:34 ` Arjan van de Ven
2005-12-28 21:02 ` Linus Torvalds
2005-12-28 21:17 ` Arjan van de Ven
2005-12-28 21:23 ` Ingo Molnar
2005-12-28 21:48 ` Ingo Molnar
2005-12-28 23:56 ` Krzysztof Halasa
2005-12-29 7:41 ` Ingo Molnar
2005-12-29 8:02 ` Dave Jones
2005-12-29 19:44 ` Krzysztof Halasa
2005-12-29 4:11 ` Andrew Morton
2005-12-29 7:32 ` Ingo Molnar
2005-12-29 14:58 ` Horst von Brand
2005-12-29 15:40 ` Adrian Bunk
2005-12-29 17:41 ` Linus Torvalds
2005-12-29 18:42 ` Arjan van de Ven
2005-12-29 18:45 ` Arjan van de Ven
2005-12-29 20:19 ` Ingo Molnar
2005-12-29 22:20 ` Matt Mackall
2005-12-29 20:28 ` Dave Jones
2005-12-29 20:49 ` Linus Torvalds
2005-12-29 21:25 ` Linus Torvalds
[not found] ` <20051229224839.GA12247@elte.hu>
2005-12-29 22:58 ` Arjan van de Ven
2005-12-30 2:03 ` Tim Schmielau
2005-12-30 2:15 ` Tim Schmielau
2005-12-30 7:49 ` Ingo Molnar
2005-12-31 14:38 ` Adrian Bunk
2005-12-31 14:45 ` Ingo Molnar
2005-12-31 15:08 ` Adrian Bunk
2006-01-02 10:37 ` Ingo Molnar
2006-01-02 10:48 ` Arjan van de Ven
2006-01-02 13:43 ` Adrian Bunk
2006-01-02 14:05 ` Ingo Molnar
2006-01-02 15:01 ` Adrian Bunk
2006-01-02 18:44 ` Krzysztof Halasa
2006-01-02 18:51 ` Arjan van de Ven
2006-01-02 19:49 ` Krzysztof Halasa
2006-01-02 19:54 ` Arjan van de Ven
2006-01-02 20:05 ` Krzysztof Halasa
2006-01-02 20:18 ` Jörn Engel
2006-01-02 22:23 ` Russell King
2006-01-02 23:55 ` Alan Cox
2006-01-03 3:59 ` Daniel Jacobowitz
2006-01-03 8:53 ` Russell King
2006-01-03 8:56 ` Arjan van de Ven
2006-01-03 9:00 ` Russell King
2006-01-03 9:10 ` Arjan van de Ven
2006-01-03 9:14 ` Vitaly Wool
2006-01-02 19:03 ` Andrew Morton
2006-01-02 19:17 ` Jakub Jelinek
2006-01-02 19:30 ` Andrew Morton
2006-01-02 19:41 ` Linus Torvalds
2006-01-02 19:53 ` Ingo Molnar
2006-01-02 20:28 ` Jakub Jelinek
2006-01-02 20:09 ` Ingo Molnar
2006-01-02 20:24 ` Andrew Morton
2006-01-02 20:40 ` Ingo Molnar
2006-01-02 20:30 ` Ingo Molnar
2006-01-02 19:12 ` Linus Torvalds
2006-01-02 19:59 ` Krzysztof Halasa
2006-01-02 20:13 ` Ingo Molnar
2006-01-02 21:00 ` Jan Engelhardt
2006-01-02 22:43 ` Linus Torvalds
2006-01-02 13:42 ` Adrian Bunk
2006-01-02 18:28 ` Andrew Morton
2006-01-02 18:49 ` Arjan van de Ven
2006-01-02 19:26 ` Jörn Engel
2006-01-02 21:51 ` Grant Coady
2006-01-02 22:03 ` Antonio Vargas
2006-01-02 22:56 ` Arjan van de Ven
2006-01-02 23:10 ` Grant Coady [this message]
2006-01-02 23:57 ` Alan Cox
2006-01-02 23:58 ` Grant Coady
2006-01-03 5:31 ` Nick Piggin
2006-01-03 23:40 ` Martin J. Bligh
2006-01-04 4:28 ` Matt Mackall
2006-01-04 5:51 ` Martin J. Bligh
2006-01-04 17:10 ` Matt Mackall
2006-01-04 22:37 ` Linus Torvalds
2006-01-05 0:55 ` Martin Bligh
2006-01-04 17:36 ` Zwane Mwaikambo
2005-12-31 3:51 ` Kurt Wall
2005-12-30 3:31 ` Nicolas Pitre
2005-12-29 22:41 ` userspace breakage Dave Jones
2005-12-29 21:23 ` Jeff V. Merkey
2005-12-29 23:42 ` Linus Torvalds
2005-12-29 22:17 ` Jeff V. Merkey
2005-12-30 0:10 ` Linus Torvalds
2005-12-29 23:54 ` Jeff V. Merkey
2005-12-30 0:32 ` Linus Torvalds
2005-12-30 14:45 ` Jeff V. Merkey
2005-12-30 16:17 ` Rik van Riel
2005-12-30 15:01 ` Jeff V. Merkey
2005-12-30 11:17 ` Bernd Petrovitsch
2005-12-30 14:59 ` Jeff V. Merkey
2005-12-30 20:22 ` Steven Rostedt
2005-12-30 21:26 ` Linus Torvalds
2005-12-30 23:49 ` Andrew Morton
2005-12-31 8:33 ` Arjan van de Ven
2005-12-31 15:30 ` Steven Rostedt
2005-12-31 16:40 ` Francois Romieu
2005-12-30 11:19 ` Bernd Petrovitsch
2005-12-30 14:53 ` Jeff V. Merkey
2005-12-30 17:17 ` Bernd Petrovitsch
2005-12-29 22:47 ` Ismail Donmez
2005-12-29 22:56 ` Linus Torvalds
2005-12-29 23:03 ` Dave Jones
2006-01-03 20:28 ` Greg KH
2006-01-03 20:37 ` Dave Jones
2006-01-04 23:00 ` Paolo Ciarrocchi
2006-01-05 4:42 ` Greg KH
2005-12-29 23:25 ` Adrian Bunk
2005-12-29 23:52 ` Linus Torvalds
2005-12-30 8:09 ` Arjan van de Ven
2006-01-03 20:28 ` Greg KH
2005-12-29 23:07 ` Dmitry Torokhov
2005-12-30 0:38 ` Ryan Anderson
2005-12-30 0:46 ` Dave Jones
2005-12-30 1:05 ` Linus Torvalds
2005-12-30 1:19 ` Dave Airlie
2005-12-30 1:21 ` Dave Jones
2005-12-30 2:10 ` Jiri Slaby
2005-12-30 2:14 ` Dave Jones
2005-12-30 2:35 ` Jiri Slaby
2005-12-30 5:14 ` Theodore Ts'o
2005-12-30 0:49 ` Linus Torvalds
2005-12-30 3:47 ` [patch 00/2] improve .text size on gcc 4.0 and newer compilers Mark Lord
2005-12-30 3:56 ` Dave Jones
2005-12-30 3:57 ` Mark Lord
2005-12-30 4:02 ` Dave Jones
2005-12-30 4:11 ` Mark Lord
2005-12-30 4:14 ` Mark Lord
2005-12-30 4:20 ` Mark Lord
2005-12-30 5:04 ` Dave Jones
2005-12-29 23:16 ` Willy Tarreau
2005-12-30 8:05 ` Arjan van de Ven
2005-12-30 8:15 ` Willy Tarreau
2005-12-30 8:24 ` Arjan van de Ven
2005-12-30 9:20 ` Willy Tarreau
2005-12-30 13:38 ` Adrian Bunk
2005-12-30 8:33 ` Jesper Juhl
2005-12-30 9:28 ` Willy Tarreau
2005-12-30 9:37 ` Jesper Juhl
2005-12-30 9:38 ` Willy Tarreau
2005-12-30 19:53 ` Alistair John Strachan
2005-12-29 7:49 ` Arjan van de Ven
2005-12-29 15:01 ` Horst von Brand
2005-12-30 15:28 ` Alan Cox
2005-12-30 20:59 ` Adrian Bunk
2005-12-30 22:12 ` Matt Mackall
2005-12-30 23:54 ` Adrian Bunk
2005-12-31 9:20 ` Arjan van de Ven
2005-12-29 14:38 ` Christoph Hellwig
2005-12-29 14:54 ` Arjan van de Ven
2005-12-29 15:35 ` Adrian Bunk
2005-12-29 15:38 ` Arjan van de Ven
2005-12-29 15:42 ` Jakub Jelinek
2005-12-29 19:14 ` Adrian Bunk
2005-12-30 9:28 ` Andi Kleen
2005-12-30 9:40 ` Ingo Molnar
2005-12-30 10:14 ` Ingo Molnar
2005-12-30 13:31 ` Adrian Bunk
2005-12-30 14:08 ` Christian Trefzer
2005-12-30 10:25 ` Andi Kleen
2005-12-29 0:37 ` Rogério Brito
2006-01-03 3:36 ` Daniel Jacobowitz
2005-12-29 4:38 ` Adrian Bunk
2005-12-29 7:59 ` Ingo Molnar
2005-12-29 13:52 ` Adrian Bunk
2005-12-29 19:57 ` Horst von Brand
2005-12-29 20:25 ` Ingo Molnar
2005-12-31 15:22 ` Adrian Bunk
2006-01-05 0:55 Chuck Ebbert
2006-01-05 1:07 ` Martin Bligh
2006-01-05 12:19 ` Arjan van de Ven
2006-01-05 14:30 ` Jakub Jelinek
2006-01-05 16:55 ` Linus Torvalds
2006-01-05 18:42 ` Daniel Jacobowitz
2006-01-05 17:02 ` Matt Mackall
2006-01-05 17:59 ` Martin Bligh
2006-01-05 18:09 ` Arjan van de Ven
2006-01-05 18:43 ` Daniel Jacobowitz
2006-01-05 19:17 ` Linus Torvalds
2006-01-05 19:40 ` Linus Torvalds
2006-01-05 19:49 ` Martin Bligh
2006-01-05 20:13 ` Linus Torvalds
2006-01-05 20:15 ` Linus Torvalds
2006-01-05 23:30 ` Ingo Molnar
2006-01-05 23:54 ` Linus Torvalds
2006-01-06 0:15 ` Ingo Molnar
2006-01-06 0:27 ` Linus Torvalds
2006-01-06 0:54 ` Ingo Molnar
2006-01-06 0:02 ` Martin Bligh
2006-01-06 0:40 ` Ingo Molnar
2006-01-06 0:55 ` Martin Bligh
2006-01-06 1:48 ` Mitchell Blank Jr
2006-01-06 0:50 ` Mitchell Blank Jr
2006-01-06 0:58 ` Ingo Molnar
2006-01-06 1:22 ` Mitchell Blank Jr
2006-01-05 21:34 ` Matt Mackall
2006-01-05 22:08 ` Linus Torvalds
2006-01-05 22:36 ` Matt Mackall
2006-01-05 22:49 ` Martin Bligh
2006-01-05 23:02 ` Matt Mackall
2006-01-05 22:55 ` Ingo Molnar
2006-01-05 23:11 ` Matt Mackall
2006-01-05 23:27 ` Jesse Barnes
2006-01-05 23:58 ` Ingo Molnar
2006-01-05 21:32 ` Grzegorz Kulewski
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