pentium4 gcc options

Robert Connolly robert at
Wed Mar 2 08:12:43 PST 2005

I have a prescott (model 3, flag pni). Between gcc benchmarks and glibc 
build/tests I'm finding '-march=i686 -mtune=prescott' works best together.

My gcc-3.4.3 benchmarks like march=pentium3 best, but that makes one glibc 
test fail. march=pentium4 also makes that test fail. Performance of 
march=pentium3 and march=pentium4 are almost identical, but maybe my gcc 
benchmarks aren't trying to take advantage of the new cpu flags.

Using march=prescott produces slower programs than march=i386, for whatever 

Google doesn't agree with my findings, but I think a lot of people are 
shooting in the dark and assuming march=prescott is ideal.

I'm also using -O3 and --enable-omitfp with good results btw.


On March 1, 2005 03:19 pm, Robert Connolly wrote:
> Hi. I have a pentium-4 3ghz 1mb cache. Should I be expecting better results
> with march=pentium3 with gcc-3.4.3? because for some reason it's performing
> better than march=pentium4. Google has some references to march=pentium4
> being not good with gcc-3.2, but no word on gcc-3.4.
> robert

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