linux-kernel - Re: [RANDOM] Move two variables to read

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Message-ID: <20071216181455.GD14233@stusta.de>
Date:	Sun, 16 Dec 2007 19:14:55 +0100
From:	Adrian Bunk <bunk@...nel.org>
To:	Eric Dumazet <dada1@...mosbay.com>
Cc:	Matt Mackall <mpm@...enic.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: [RANDOM] Move two variables to read_mostly section to save
	memory

On Sun, Dec 16, 2007 at 06:42:57PM +0100, Eric Dumazet wrote:
> Adrian Bunk a écrit :
>...
>> And even more funny, with gcc 4.2 and CONFIG_CC_OPTIMIZE_FOR_SIZE=y your 
>> patch doesn't seem to make any space difference - are you using an older 
>> compiler or even worse CONFIG_CC_OPTIMIZE_FOR_SIZE=n for being able to see 
>> any space difference?
>>
>> In both cases your code uglification would be even more pointless...
>>
>
> I believe that CONFIG_SMP is uglification for you Adrian, but still I am 
> glad linux have it.
>
> If your CONFIG_SYSCTL=n is really that important for you, why dont you 
> define a new qualifier that can indeed mark some variables as :
>
> const if CONFIG_SYSCTL=n
> read_mostly if CONFIG_SYCTL=y
>
> This way you can keep compiler optimizations for your CONFIG_SYCTL=n, while 
> many people like me can still continue to optimize their kernel.
>
> Seeing so many sysctl already read_mostly in kernel, I wonder why you NACK 
> my patch, while it's easy to share your concerns with other people and find 
> a solution.

You omitted an answer to my main important point...

Let me ask it in a more simple way:

Do you see any space difference at all with gcc 4.2 and 
CONFIG_CC_OPTIMIZE_FOR_SIZE=y ?

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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