Re: GNAT's stack checking in Ubuntu 9.04 (and Shootout regex-dna)

[jonathan <johnscpg@googlemail.com>]

On Aug 11, 12:34 am, Georg Bauhaus <rm.tsoh.plus-
bug.bauh...@maps.futureapps.de> wrote:

> Does regexdna-multi.ada work on your system?
>
> On a dual core system it seems to be shortening
> the running time by almost a third.
>
Yes, regexdna-multi.ada so far works
on the compiler and machine combinations I've tried.

With

  Stack_Size : constant Positive := 37;

I get 31 second running time on 1-core, 15 second
running time on 4-cores.

The tasking-free version uses 30.5 seconds on 1-core.
This is a 3.2 GHz 4-core machine.

Actually, as I was writing that I remembered its really
an 8-core machine.  SO just for fun I set

  Max_CPUs : constant := 7;

and it ran in 12 seconds.  In fact it ran in 12 seconds
for 5, 6, 7 and 8 CPU's.  Then I couldn't resist.
I set it to 15:

  Max_CPUs : constant := 15;

It ran  in 9 seconds.  I couldn't believe it. I
timed it with my watch also.  The best time was
8.7 seconds. In fact all settings of Max_CPUs
from 9 to 15 ran in  9 seconds. At Max_CPUs = 24
it was 9.7 sec.

Jonathan