Re: [PATCH -v7][RFC]: mutex: implement adaptive spinning

[Andi Kleen <andi@firstfloor.org>]

On Sun, Jan 11, 2009 at 12:26:41PM +0000, David Woodhouse wrote:
>   - Unconditionally have 'inline' meaning 'always_inline'. If we say it,
>     we should mean it.
> 
>   - Resist the temptation to use -fno-inline-functions. Allow GCC to
>     inline other things if it wants to.

The proposal was to use -fno-inline-functions-called-once (but 
the resulting numbers were not promising)

We've never allowed gcc to inline any other functions not marked
inline explicitely because that's not included in -O2. 

>   - Reduce the number of unnecessary 'inline' markers, and have a policy
>     that the use of 'inline' should be accompanied by either a GCC PR#
>     or an explanation of why we couldn't reasonably have expected GCC to
>     get this particular case right.
> 
>   - Have a similar policy of PR# or explanation for 'uninline' too.
> 
> I don't think we should just give up on GCC ever getting it right. That
> way lies madness. As we've often found in the past. 

It sounds like you're advocating to set -O3/-finline-functions
by default.   Not sure that's a good idea.

-Andi

-- 
ak@linux.intel.com