Why exactly whould you not touch the -march options? I have had no
problems using them, and my system (5.0-CURRENT) seems a little faster
with -march=i686. I could be wrong though as I havn't done any exact
tests... it just seems a bit more responsive..
=================================================================
| Kenneth Culver | FreeBSD: The best OS around. |
| Unix Systems Administrator | ICQ #: 24767726 |
| and student at The | AIM: muythaibxr |
| The University of Maryland, | Website: (Under Construction) |
| College Park. | http://www.wam.umd.edu/~culverk/|
=================================================================
On Sat, 8 Apr 2000, Matthew Dillon wrote:
> :On Sat, 8 Apr 2000, Alexey N. Dokuchaev wrote:
> :
> :> AFAIK, Linux Mandrake has it's kernel and userland highly optimized for
> :> Pentium architecture. However, they have additional gcc optimization
> :> flags turned on by default, including -O3 and -mfast_math.
> :
> :Can you say "gimmick"? :-) gcc often produces demonstrably broken code for
> :optimisation levels higher than -O.
> :
> :Probably the only useful and safe option apart from -O is the
> :-march=pentium/pentiumpro/pentiumii/etc option for using
> :processor-specific opcodes and instruction scheduling.
> :Kris
>
> I use -Os for everything. I wouldn't bother with anything else. Someone
> ran a bunch of benchmarks with various gcc/egcs options a while back
> and, frankly, the top half dozen combinations were so close to each
> other performance-wise that it just didn't matter. -Os was in that
> group, but also produced significantly smaller binaries.
>
> I wouldn't touch the -march stuff at all, nor would I use -O3 (which
> tries to inline standard static functions verses -O2) - that's useless
> on IA32 because call/returns are very fast (I had an argument with John
> Dyson about call/return overhead verses an L1 cache miss and
> we ran a bunch of timings. I lost the argument :-) call/return won the
> race handily).
>
>
> -Matt
> Matthew Dillon
> <[EMAIL PROTECTED]>
>
>
> To Unsubscribe: send mail to [EMAIL PROTECTED]
> with "unsubscribe freebsd-hackers" in the body of the message
>
To Unsubscribe: send mail to [EMAIL PROTECTED]
with "unsubscribe freebsd-hackers" in the body of the message
