From: Gerd Stolpmann <info@gerd-stolpmann.de>
To: Yotam Barnoy <yotambarnoy@gmail.com>
Cc: Ocaml Mailing List <caml-list@inria.fr>
Subject: Re: [Caml-list] Concurrent/parallel programming
Date: Wed, 08 Jan 2014 12:36:41 +0100 [thread overview]
Message-ID: <1389181001.2999.46.camel@e130> (raw)
In-Reply-To: <CAN6ygOmhe4CFXcBFLMJ-5R3RF8puwRc167CgXiditC8EywvmxA@mail.gmail.com>
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Am Dienstag, den 07.01.2014, 21:35 -0500 schrieb Yotam Barnoy:
> Thanks for the links and info, everyone.
>
> Gerd, would it be possible to put netmulticore up on opam? I realize
> this is a sensitive topic for you, but from what I can tell, this is
> the most comprehensive and efficient solution to parallel programming
> that exists for ocaml, so why not make it as easily available as
> possible?
Netmulticore is part of Ocamlnet, and I guess you can get it by simply
installing ocamlnet with opam. I'm not the maintainer, so I don't know
whether it is included or not.
> Also, regarding the ocaml_modify() and ocaml_initialize() regression
> in 4.01 -- yikes! Is there any way to get support back for writing
> outside of the ocaml heap? This seems like a pretty big deal! (Sorry
> if I'm arriving late for whatever discussion took place about this
> before).
There is a workaround in place - so far the OS supports it: thanks to
Xavier the symbols caml_modify and caml_initialize are declared as weak
in 4.01, allowing them to be redefined in executables. Netmulticore
redefines these symbols with their pre-4.01 functions.
This isn't optimal yet, because the old write barriers are a bit slower,
and because this introduces a very low-level dependency on the current
version of Ocaml. Nevertheless, it works for now. (Ideas for a better
solution are highly welcome.)
Gerd
>
> -Yotam
>
>
>
> On Tue, Jan 7, 2014 at 3:35 PM, Gerd Stolpmann
> <info@gerd-stolpmann.de> wrote:
> There is Netmulticore, a part of Ocamlnet:
>
> http://projects.camlcity.org/projects/dl/ocamlnet-3.7.3/doc/html-main/Intro.html#ch_comp
>
> It utilizes shared memory, and accesses it from several
> processes. There
> is no C code involved, but it is fairly unsafe nevertheless,
> because you
> need to stick to certain programming rules, or the program
> crashes.
> However, if you manage to encapsulate all the unsafe things,
> it is a
> good option. I'm using Netmulticore in the Plasma Map/Reduce
> implementation.
>
> Gerd
>
> Am Dienstag, den 07.01.2014, 14:54 -0500 schrieb Yotam Barnoy:
> > Hi List
> >
> >
> > So far, I've been programming in ocaml using only sequential
> programs.
> > In my last project, which was an implementation of a large
> machine
> > learning algorithm, I tried to speed up computation using a
> little bit
> > of parallelism with ParMap, and it was a complete failure.
> It's
> > possible that more time would have yielded better results,
> but I just
> > didn't have the time to invest in it given how bad the
> initial results
> > were.
> >
> >
> > My question is, what are the options right now as far as
> parallelism
> > is concerned? I'm not talking about cooperative
> multitasking, but
> > about really taking advantage of multiple cores. I'm well
> aware of the
> > runtime lock and I'm ok with message passing between
> processes or a
> > shared area in memory, but I'd rather have something more
> high level
> > than starting up several processes, creating a named pipe or
> a socket,
> > and trying to pass messages through that. Also, I assume
> that using a
> > shared area in memory involves some C code? Am I wrong about
> that?
> >
> >
> > I was expecting Core's Async to fill this role, but
> realworldocaml is
> > fuzzy on this topic, apparently preferring to dwell on
> cooperative
> > multitasking (which is fine but not what I'm looking for),
> and I
> > couldn't find any other documentation that was clearer.
> >
> >
> > Thanks
> >
> > Yotam
> >
>
>
> --
> ------------------------------------------------------------
> Gerd Stolpmann, Darmstadt, Germany gerd@gerd-stolpmann.de
> My OCaml site: http://www.camlcity.org
> Contact details: http://www.camlcity.org/contact.html
> Company homepage: http://www.gerd-stolpmann.de
> ------------------------------------------------------------
>
>
--
------------------------------------------------------------
Gerd Stolpmann, Darmstadt, Germany gerd@gerd-stolpmann.de
My OCaml site: http://www.camlcity.org
Contact details: http://www.camlcity.org/contact.html
Company homepage: http://www.gerd-stolpmann.de
------------------------------------------------------------
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next prev parent reply other threads:[~2014-01-08 11:36 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-07 19:54 Yotam Barnoy
2014-01-07 20:12 ` Yaron Minsky
2014-01-07 20:21 ` Yaron Minsky
2014-01-07 20:35 ` Gerd Stolpmann
2014-01-08 2:35 ` Yotam Barnoy
2014-01-08 3:33 ` Francois Berenger
2014-01-08 4:01 ` Yotam Barnoy
2014-01-08 8:37 ` Gabriel Scherer
2014-01-08 11:36 ` Gerd Stolpmann [this message]
2014-01-08 11:55 ` Mark Shinwell
2014-01-08 13:38 ` Gerd Stolpmann
2014-01-07 21:51 ` Markus Mottl
[not found] ` <20140107200328.GA14297@voyager>
2014-01-08 1:12 ` Francois Berenger
2014-01-08 20:29 ` Roberto Di Cosmo
2014-01-08 22:13 ` Yotam Barnoy
2014-01-08 22:38 ` Anil Madhavapeddy
2014-01-08 22:57 ` [Caml-list] [ocaml-infra] " Ashish Agarwal
2014-01-09 2:52 ` Yotam Barnoy
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