Re: BUG #13498: make check failures

I dont at this time have GCC installed. The goal was to be able to take
advantage of optimization that understood the actual hardware

by setting -qarch=pwr7 -qtune=pwr7 the xlc compiler starting at -O3 up to
-O5 make optimization decisions that are unique to the hardware, in this
case the p7 architecture,

O4 and O5 then take it quite a but more, O5 can take what compiles in a a
few second to more then 10 minutes.

It is pretty rare that -O3 used with -strict will break anything, actually
this is the first time I've seen it happen.





On Mon, Jul 13, 2015 at 2:20 PM, Andres Freund <andres@anarazel.de> wrote:

> On 2015-07-13 14:15:58 -0700, Pete Lancashire wrote:
> > I'll agree to a point.
> >
> > I'll see what else I can find out. Is there an option to make the test
> more
> > verbose ? And I'll see what I can get out of the what changes the
> > optimization does
> >
> > Its a pitty, I'd love to get postgresql screaming on a P-series. In other
> > things level 3 can increase the performance 20-30% and level 5 in one
> > program that does a lot of array searching 50-70%
>
> You could try with gcc -O3...
>
>