From: Matt Mackall <mpm@selenic.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Linus Torvalds <torvalds@osdl.org>, Andrew Morton <akpm@osdl.org>,
arjan@infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [patch 00/2] improve .text size on gcc 4.0 and newer compilers
Date: Thu, 29 Dec 2005 16:20:59 -0600 [thread overview]
Message-ID: <20051229222059.GC3356@waste.org> (raw)
In-Reply-To: <20051229201953.GA29546@elte.hu>
On Thu, Dec 29, 2005 at 09:19:53PM +0100, Ingo Molnar wrote:
>
> * Linus Torvalds <torvalds@osdl.org> wrote:
>
> > > i think there's quite an attitude here - we are at the mercy of "gcc
> > > brainfarts" anyway, and users are at the mercy of "kernel brainfarts"
> > > just as much.
> >
> > There's a huge difference here. The gcc people very much have a "Oh,
> > we changed old documented behaviour - live with it" attitude, together
> > with "That was a gcc extension, not part of the C language, so when we
> > change how gcc behaves, it's _your_ problem" approach.
> >
> > At least they used to.
>
> yeah, i think that was definitely the case historically.
>
> > Maybe the right thing to do is to just heed that warning, and remove
> > such functions from header files and make them no-inline? That way we
> > get the size fixes _regardless_ of any compiler options.
>
> i think the eye-opener (for me at least) was that there's really a
> massive 5%+ size difference here, from 2 simple patches. And meanwhile
> Matt is doing truly hard size-reduction work and is mailing patches to
> lkml that remove 200-300 bytes of .text, which is 0.01% of code, apiece.
For the record, my cut-off for non-trivial stuff is currently about
1K. Which is more like 0.1% for minimal kernels. Unfortunately, the
impact of these patches on a stripped-down kernel is less substantial
than on a featureful one, so
> Debloating is like scalability, a piece-by-piece process where we'll
> only see the full effects after doing 100 independent steps, but still
> we must not ignore the big effects either, nor must we get ourselves
> into losing maintainance battles.
>
> The current inline model seems to be a lost battle, the 'size noise'
> caused by spurious inlines (which count in the thousands) is _far_
> outpowering most of the size reduction efforts. And i think it can be
> argued that at least in the -Os case gcc has a very clear directive wrt.
> what to do - and much less room to mess up. Independently of how much we
> trust it.
I think both these patches deserve a spin in -mm. But I can see
arguments for staging it. Hopefully we can get Andrew to take the
unit-at-a-time piece for post-2.6.15 and try out the inlining after
we've got some confidence with the first.
--
Mathematics is the supreme nostalgia of our time.
next prev parent reply other threads:[~2005-12-29 22:24 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 [this message]
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
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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