On Fri, 9 Mar 2001, Thor Lancelot Simon wrote:

> On Fri, Mar 09, 2001 at 08:23:09AM +0100, wojtek@wojtek.from.pl wrote:
> > > > > pkgsrc collection, should therefore run on any 1.5/i386. You can build
> > > >
> > > > all binaries compiled with -mpentiumpro RUNS on any i386!
> > >
> > > So what?  All -mpentiumpro changes is the instruction scheduling.
> >
> > yes. because of that it's good as default option - it runs still same fast
> > on 386 for example.
>
> No, it doesn't.  Or, if it does, then gcc's instruction scheduling for the
> 386 is broken.
>
> Timings for many instructions are radically different on the i386 than on
> the Pentium Pro.

	I seem to recall someone commenting that -mpentiumpro gives a
	slight drop in performance for 386 and 486 chips, and a bigger
	gain everywhere else.

	If so it might still be worth considering for the default.

	Actually, does anyone have a reference to a table of relative
	gain/loss and compatability for i386 -march and -mcpu options?
	It would be good to get that information up on the netbsd site
	to give more people the right information to select optimisation.

		David/absolute		-- www.netbsd.org: No hype required --