On Mon, Jun 29, 2009 at 10:59:57AM -0600, Zan Lynx wrote:

Andi Kleen wrote:

quoted

At least on x86 I can't see how it happens. mb() is only a compile
time barrier and the compiler doesn't optimize over indirect callbacks
like __pollwait() anyways.

Just a note about this. That used to be true, that GCC didn't optimize 
indirect calls. However, see -findirect-inlining in GCC 4.4.

I am aware of that, but ...

I am not saying that it applies here, but it is something to remember.

... it doesn't apply here because it works only for a few very simple
cases that don't apply for this code. Besides the kernel builds with -O2,
which only inlines functions called once or very small functions, which
also rules this out.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.