From: Matt Mackall <mpm@selenic.com>
To: Adrian Bunk <bunk@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: RFC: remove __read_mostly
Date: Fri, 14 Dec 2007 09:24:55 -0600 [thread overview]
Message-ID: <20071214152454.GR17536@waste.org> (raw)
In-Reply-To: <20071213222044.GH21616@stusta.de>
On Thu, Dec 13, 2007 at 11:20:44PM +0100, Adrian Bunk wrote:
> I tried the following patch with a full x86 .config [1]:
>
> --- a/include/asm-x86/cache.h
> +++ b/include/asm-x86/cache.h
> -#define __read_mostly __attribute__((__section__(".data.read_mostly")))
> +/* #define __read_mostly __attribute__((__section__(".data.read_mostly"))) */
>
> The result [2,3] was:
>
> -rwxrwxr-x 1 bunk bunk 46607243 2007-12-13 19:50 vmlinux.old
> -rwxrwxr-x 1 bunk bunk 46598691 2007-12-13 21:55 vmlinux
>
> It's not a surprise that the kernel can become bigger when __read_mostly
> gets used, especially in cases where __read_mostly prevents gcc
> optimizations.
>
> My question is:
> Is there anywhere in the kernel a case where __read_mostly brings a
> measurable improvement or can it be removed?
Yes, but perhaps we can put it under CONFIG_BASE_FULL?
--
Mathematics is the supreme nostalgia of our time.
next prev parent reply other threads:[~2007-12-14 15:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-13 22:20 RFC: remove __read_mostly Adrian Bunk
2007-12-13 22:29 ` Andi Kleen
2007-12-13 22:41 ` Adrian Bunk
2007-12-14 16:16 ` Arnd Bergmann
2007-12-14 16:31 ` Eric Dumazet
2007-12-13 22:32 ` David Miller
2007-12-13 22:44 ` Harvey Harrison
2007-12-13 23:06 ` Andi Kleen
2007-12-13 22:48 ` Eric Dumazet
2007-12-13 23:00 ` Adrian Bunk
2007-12-13 23:54 ` Kyle McMartin
2007-12-14 0:33 ` Andi Kleen
2007-12-17 10:33 ` Andrew Morton
2007-12-17 10:53 ` Eric Dumazet
2007-12-17 11:07 ` Andrew Morton
2007-12-17 12:19 ` Andi Kleen
2007-12-17 12:15 ` Andi Kleen
2007-12-17 12:40 ` Adrian Bunk
2007-12-14 15:24 ` Matt Mackall [this message]
2007-12-14 15:38 ` Eric Dumazet
2007-12-14 15:42 ` Matt Mackall
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