Re: [Caml-list] Memory allocation nano-benchmark.

["Frédéric Gava" <frederic.gava@wanadoo.fr>]

Hi,

There is a function in the stdlid for have a beter code:

let test tablesize =
  let table = Array.create tablesize [| [| |] |] in
  for i=0 to tablesize - 1 do
     table.(i) <-   Array.make_matrix tablesize tablesize 0
  done;
...

smaller code no ? ;-)

> The results (on an AMD 2000XP):
>
> chris@gentoo:~/test$ ocamlopt -unsafe -inline 40 memnew.ml
> chris@gentoo:~/test$ a.out 300
> chris@gentoo:~/test$ time a.out 300
> real    0m1.560s
> user    0m1.391s
> sys     0m0.105s
>
> chris@gentoo:~/test$ ocamlopt -unsafe -inline 40 mem.ml
> chris@gentoo:~/test$ time a.out 300
> real    0m2.106s
> user    0m1.904s
> sys     0m0.106s
>
> chris@gentoo:~/test$ gcc -O3 -fomit-frame-pointer mem.c
> chris@gentoo:~/test$ time a.out 300
> real    0m0.380s
> user    0m0.283s
> sys     0m0.072s
>
> So, yours is slightly faster, but both are in the same ballpark
> and the C version is at least 4X faster.

:-(

Peraps due to the fact that "int" are boxed. Try to give "options you give
to gcc" to ocamlopt
to link optimized code. Else I do not know how to optimize this code "in a
pure ocaml way" (i.e without trick with C code). Is caml guru, wizards or
ocaml's creators have an idea ?

Regards,
Frédéric Gava