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Re: [Caml-list] Optimizing garbage collection
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 Date: 2010-11-23 (16:43) From: Christophe Raffalli Subject: Re: [Caml-list] Optimizing garbage collection
```Le 23/11/2010 14:40, Christophe Raffalli a écrit :
>
> Hello,
>
> May be running a minimisation algorithm to minimize (promoted_words per
> minor collection / minor_heap_size)  Could be good ?
>

This was stupid has it converges toward zero when we increase minor_heap_size.

However, the following piece of code worked well for PML benchmark (4'30" became 3'02") :
(remark that HALVING the minor_heap_size does occur too)

I really do not know if such strategy is reasonnable as a default ?
If the 0.10 and 0.005 in the code are any reasonnable ?

-------------------8<---------------------
open Gc

let param = get ()

let old_promoted_words = ref 0.0
let old_minor_collections = ref 0
let minor_heap_size = ref param.minor_heap_size

let _ = create_alarm (fun () ->
let s = quick_stat () in
let promoted_words = s.promoted_words in
let minor_collections = s.minor_collections in
let delta_promoted_words = promoted_words -. !old_promoted_words in
let delta_minor_collections = minor_collections - !old_minor_collections in
old_promoted_words := promoted_words;
old_minor_collections := minor_collections;
let ratio = delta_promoted_words /. (float) delta_minor_collections
/. (float) !minor_heap_size
in
if ratio > 0.10 then begin
minor_heap_size := !minor_heap_size * 2;
(*  Printf.fprintf stderr "MHS DOUBLED <- %d (ratio %f)\n" !minor_heap_size ratio;
flush stderr; *)
set { get () with minor_heap_size = !minor_heap_size }
end else if ratio < 0.005 then begin
minor_heap_size := max 32768 (!minor_heap_size / 2);
(*  Printf.fprintf stderr "MHS HALFED <- %d (ratio %f)\n" !minor_heap_size ratio;
flush stderr; *)
set { get () with minor_heap_size = !minor_heap_size }
end)
-------------------8<---------------------

--
Christophe Raffalli
Universite de Savoie
Batiment Le Chablais, bureau 21
73376 Le Bourget-du-Lac Cedex

tel: (33) 4 79 75 81 03
fax: (33) 4 79 75 87 42
mail: Christophe.Raffalli@univ-savoie.fr
www: http://www.lama.univ-savoie.fr/~RAFFALLI
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```