Messages in this thread | | | Date | Sat, 6 Mar 1999 22:29:23 -0500 | From | Arvind Sankar <> | Subject | Re: glibc-2.1 upgrade headaches. Any ideas?? |
| |
On Sun, Mar 07, 1999 at 02:09:17PM +1100, CaT wrote: > I've been happily doing it for a while with -O2 optimisation and > -march=pentiumpro and haven't had a single kernel crash. > > I'd use -O6 but I can't find any info on what the hell this does > as far as optimisation goes.
The biggest you can go to currently is -O3, I believe. Anything beyond that turns on the same flags.
> > And is -fomit-frame-pointer a workaround for a bug in some implimentations > of -O2 (I compiled X without it and it's working fine. Hasn't crashed) or > is it something the kernel needs? And, what exactly does this do? I've read > the manpage but what that has doesn't mean much to me. I wish there was > info on not just what an optimisation flag does but also how it might effect > performance and what sideeffects it might have. (this is probably real hard > to do but it would be way useful. I don't mind long compile times as long > as runtime performance is imporved) From the gcc manual:
`-fomit-frame-pointer' Don't keep the frame pointer in a register for functions that don't need one. This avoids the instructions to save, set up and restore frame pointers; it also makes an extra register available in many functions. *It also makes debugging impossible on some machines.*
This option is never turned on by default (on i386), so the kernel Makefile turns it on.
Obviously, it should improve run-time performance, unless the gcc code optimizer is so buggy that it generates faster code with less registers available ;)
-- arvind
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |