Re: Help text for config OPTIMIZE_INLINING

Re: Help text for config OPTIMIZE_INLINING

[Sitsofe Wheeler]

> From: Ingo Molnar <mingo@elte.hu>

> 
> * Sitsofe Wheeler wrote:
>  
> > While [this] suggests that one should set it to y to generate smaller 
> > kernels. My own experience says that setting it to y DOES generate a 
> > smaller kernel so perhaps the main text should be changed to reflect 
> > this?
> 
> sure, could you send a patch (with lkml Cc:-ed) that does this?

Will do (I won't send it via Yahoo mail though because it will be mangled).

> Also, would be nice if you sent with/without vmlinux size numbers for 
> the config you are using. Btw., do you have 

5463127 2008-10-11 19:51 vmlinux.no-opt
5456152 2008-10-11 19:56 vmlinux.opt

So about 6975 bytes smaller. This is a config which is vastly cut down, compiler was gcc version 4.1.2 20070925 (Red Hat 4.1.2-33) on Fedora 8.

> CONFIG_CC_OPTIMIZE_FOR_SIZE=y enabled as well? That too shrinks the 
> kernel (which speeds it up as well on moder CPUs), quite visibly.

In the past I've tried it out but it seemed to make my crude benchmark (glxgears) go slower...



      

Help text for config OPTIMIZE_INLINING

[Sitsofe Wheeler]

The main help text for the OPTIMIZE_INLINING kconfig option says:
"The gcc 4.x series have a rewritten inlining algorithm and disabling this option will generate a smaller kernel there."

That suggests that to generate a smaller kernel one should set the option to n. However the short text says:
"Allow gcc to uninline functions marked 'inline'"

While suggests that one should set it to y to generate smaller kernels. My own experience says that setting it to y DOES generate a smaller kernel so perhaps the main text should be changed to reflect this?


 Sitsofe | http://sucs.org/~sits/



      

Re: Help text for config OPTIMIZE_INLINING

[Ingo Molnar]

* Sitsofe Wheeler <sitsofe@yahoo.com> wrote:

> The main help text for the OPTIMIZE_INLINING kconfig option says: "The 
> gcc 4.x series have a rewritten inlining algorithm and disabling this 
> option will generate a smaller kernel there."
> 
> That suggests that to generate a smaller kernel one should set the 
> option to n. However the short text says: "Allow gcc to uninline 
> functions marked 'inline'"
> 
> While suggests that one should set it to y to generate smaller 
> kernels. My own experience says that setting it to y DOES generate a 
> smaller kernel so perhaps the main text should be changed to reflect 
> this?

sure, could you send a patch (with lkml Cc:-ed) that does this?

Also, would be nice if you sent with/without vmlinux size numbers for 
the config you are using. Btw., do you have 
CONFIG_CC_OPTIMIZE_FOR_SIZE=y enabled as well? That too shrinks the 
kernel (which speeds it up as well on moder CPUs), quite visibly.

	Ingo