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

From: Eric W. Biederman
Date: Thu Aug 21 2008 - 22:24:18 EST


Andi Kleen <andi@xxxxxxxxxxxxxx> writes:

> On Thu, Aug 21, 2008 at 11:15:37AM -0700, Eric W. Biederman wrote:
>> Andi Kleen <andi@xxxxxxxxxxxxxx> 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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