linux-kernel - Re: [PATCH] Move sysctl check into debugging section and don't make it default y

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Message-ID: <m1zln5lrnl.fsf@frodo.ebiederm.org>
Date:	Thu, 21 Aug 2008 19:17:34 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Andi Kleen <andi@...stfloor.org>
Cc:	torvalds@...l.org, linux-kernel@...r.kernel.org,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH] Move sysctl check into debugging section and don't make it default y

Andi Kleen <andi@...stfloor.org> writes:

> On Thu, Aug 21, 2008 at 11:15:37AM -0700, Eric W. Biederman wrote:
>> Andi Kleen <andi@...stfloor.org> writes:
>> 
>> >> What is a feature change like this doing coming in after the
>> >> merge window?
>> >
>> > I considered it a "anti bloat bugfix". Adding 30k of 
>> > object code to allno was a bit too much. 
>> 
>> 30k???  Which platform are you testing on ia64????
>> 
>> On x86_64 it is 8k text and 8k data.
>
> x86-64 with 4.1. See the size output in the original commit.
>
>   text    data     bss     dec     hex filename
>   36243       0       0   36243    8d93 kernel/sysctl_check.o
>
> 36k actually.

With gcc-4.1.1 on x86_64 I see:

size kernel/sysctl.o  
   text    data     bss     dec     hex filename
   9133    8948     208   18289    4771 kernel/sysctl.o

And looking at the readelf output confirms that size isn't missing something
important.  That is extremely weird that you are seeing something so much different.
It does appear that I have CONFIG_CC_OPTIMIZE_FOR_SIZE=y but I am surprised that
even that would make such a difference.  Has gcc decided just to way over-optimize
that code?

Eric



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