Re: New to PostgreSQL, performance considerations

On 12/12/06, Florian Weimer <fweimer@bfk.de> 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