optimization levels for 6-STABLE build{kernel,world}

[Kris Kennaway]

On Wed, Sep 13, 2006 at 09:57:25PM -0700, Gary Kline wrote:
> On Thu, Sep 14, 2006 at 10:07:35AM +1000, Tony Maher wrote:
> > Gary Kline wrote:
> > 
> > > <deleted>
> > >
> > > 	A couple of things.  Will having gcc unroll loops have any
> > > 	negative consequences?  (I can't imagine how:: but better 
> > > 	informed than to have something crash inexplicability.)
> > > 	With 6.X safe at -O2 and with -funroll-loops, that should be
> > > 	a slight gain, right?  (It also will make an upgrade from 5.5 
> > > 	to 6.[12] that much more rational.)
> > 
> > -funroll-loops affect loader see
> > http://lists.freebsd.org/pipermail/freebsd-stable/2006-September/028145.html
> > 
> 
> 	Right.  This is probably what Chuck Swiger was talking about.
> 	I've never had this problems on my 5.[345] releases.  And not
> 	with 6.1 (knock-wood!!). 
> 
> 	I've just upgraded to -RELEASE and going to rebuild overnight on
> 	the server that traped out.  With -funroll-loops gone :-)

Just leave it alone unless you know what you're doing...fiddling with
the compiler flags just isn't going to give you a secret performance
boost for general workloads, no matter how cool it might make you feel
:)

Kris
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