On 12/12/06, Florian Weimer <[EMAIL PROTECTED]> wrote:
* Cosimo Streppone:
> "-O0" ~ 957 tps
> "-O1 -mcpu=pentium4 -mtune=pentium4" ~ 1186 tps
> "-O2 -mcpu=pentium4 -mtune=pentium4" ~ 1229 tps
> "-O3 -mcpu=pentium4 -mtune=pentium4" ~ 1257 tps
> "-O6 -mcpu=pentium4 -mtune=pentium4" ~ 1254 tps
-mcpu and -mtune are synonymous. You really should -march here (but
the result is non-generic code). Keep in mind that GCC does not
contain an instruction scheduler for the Pentium 4s. I also believe
that the GCC switches are not fine-grained enough to cover the various
Pentium 4 variants. For instance, some chips don't like the CMOV
instruction at all, but others can process it with decent speed.
You can use -march=pentium4, -march=prescott and -march=nocona to the
different Pentium4 processors. But you have to use -march (and not
-mcpu or -mtune) because without it you are still using only i386
instructions.
Daniel
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