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Date: Tue, 30 Nov 2010 09:10:36 +0100
From: Stephan Houben <stephanh@planet.nl>
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To: caml-list@yquem.inria.fr
Subject: Re: Threading and SharedMem (Re: [Caml-list] Re: Is OCaml fast?)
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X-Spam: no; 0.00; threading:01 ocaml:01 bandel:01 gerd:01 stolpmann:01 bandel:01 gerd:01 stolpmann:01 libs:01 ocaml:01 libs:01 bigarray:01 genarray:01 dims:01 rdwr:01 

On 11/29/2010 04:33 PM, Oliver Bandel wrote:
> Zitat von "Gerd Stolpmann" <info@gerd-stolpmann.de>:
>
>> Am Montag, den 29.11.2010, 17:12 +0100 schrieb Oliver Bandel:
>>> Zitat von "Gerd Stolpmann" <info@gerd-stolpmann.de>:
>>>

>>> You use shared mem(?), but you link only to *.ml files,
>>> and I see no *.c there.

>>> How can this be done?
>>>
>>> At least not via the libs that are shipped with OCaml?!

Actually it can be done using the libs that ship with OCaml
(Unix and Bigarray), although it is not 100% POSIX :

let create_shared_genarray kind layout dims =
   let fd = Unix.openfile "/dev/zero" [Unix.O_RDWR] 0
   in let ar = Bigarray.Genarray.map_file fd kind layout true dims
   in Unix.close fd; ar


The resulting bigarray object is shared among subsequent forks.
This relies on the fact that mmap-ing /dev/zero is equivalent
to an anonymous mmap.

http://en.wikipedia.org/wiki//dev/zero

Well, at least it works on Linux.

Stephan