From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Original-To: caml-list@sympa.inria.fr Delivered-To: caml-list@sympa.inria.fr Received: from mail3-relais-sop.national.inria.fr (mail3-relais-sop.national.inria.fr [192.134.164.104]) by sympa.inria.fr (Postfix) with ESMTPS id 2A82E7FA56 for ; Thu, 24 Jul 2014 17:39:26 +0200 (CEST) Received-SPF: None (mail3-smtp-sop.national.inria.fr: no sender authenticity information available from domain of mmatalka@gmail.com) identity=pra; client-ip=209.85.192.43; receiver=mail3-smtp-sop.national.inria.fr; envelope-from="mmatalka@gmail.com"; x-sender="mmatalka@gmail.com"; x-conformance=sidf_compatible Received-SPF: Pass (mail3-smtp-sop.national.inria.fr: domain of mmatalka@gmail.com designates 209.85.192.43 as permitted sender) identity=mailfrom; client-ip=209.85.192.43; receiver=mail3-smtp-sop.national.inria.fr; envelope-from="mmatalka@gmail.com"; x-sender="mmatalka@gmail.com"; x-conformance=sidf_compatible; x-record-type="v=spf1" Received-SPF: None (mail3-smtp-sop.national.inria.fr: no sender authenticity information available from domain of postmaster@mail-qg0-f43.google.com) identity=helo; client-ip=209.85.192.43; receiver=mail3-smtp-sop.national.inria.fr; envelope-from="mmatalka@gmail.com"; x-sender="postmaster@mail-qg0-f43.google.com"; x-conformance=sidf_compatible X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AkcCAEEo0VPRVcArm2dsb2JhbABYg2BXBIJ0r0aVGIFhh0UBgQUIFhABAQEBAQYLCwkUKYQDAQEBAwESER0BGxILAQMBCwYFCw0NHQICIgERAQUBChIGExIQiAsBAwkIDZxYaospgXKDEIpbChknAwpkhjIRAQUOjzkEB4J4gU4FhHEFlj2BUpB/GCmEejsv X-IPAS-Result: AkcCAEEo0VPRVcArm2dsb2JhbABYg2BXBIJ0r0aVGIFhh0UBgQUIFhABAQEBAQYLCwkUKYQDAQEBAwESER0BGxILAQMBCwYFCw0NHQICIgERAQUBChIGExIQiAsBAwkIDZxYaospgXKDEIpbChknAwpkhjIRAQUOjzkEB4J4gU4FhHEFlj2BUpB/GCmEejsv X-IronPort-AV: E=Sophos;i="5.01,724,1400018400"; d="scan'208";a="72701506" Received: from mail-qg0-f43.google.com ([209.85.192.43]) by mail3-smtp-sop.national.inria.fr with ESMTP/TLS/RC4-SHA; 24 Jul 2014 17:39:24 +0200 Received: by mail-qg0-f43.google.com with SMTP id a108so3507713qge.30 for ; Thu, 24 Jul 2014 08:39:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=urBprbwGUeC/dLw3oijtutbDbiNDERC8JnwaTn7tMLM=; b=k+lx/WhITyz7f5mTQBT/c+1d8A0OguXpn1XzacPlK7OzOgubrAhDPM3+EttoTSnwVt 1ItmV1lqiJtCy2GETECGntSG2wWAPLgbzTLr18aNPlIljuaELf66PWW6OBjBKBn+RKh3 LqO4ytUrp4eZIjYu4sEoMzB74O6g5mzfx6qKfj79pLJuFYx5KpB4/w25NXX995HH1tCT 8//WuJA3FD6/Ep4yYgQswxm0K8K1QBFObnVIfEfW0sOosEtiJWKBOxkFQgpGo/fd1mEK lz3QOgUSSLBVYUafrSSJ35CZAQwY+JCTNDfciPp+8fsWPk9Lwun5/rsswKTknIS1/bjh HjOA== MIME-Version: 1.0 X-Received: by 10.140.105.72 with SMTP id b66mr15431122qgf.30.1406216363655; Thu, 24 Jul 2014 08:39:23 -0700 (PDT) Received: by 10.140.88.81 with HTTP; Thu, 24 Jul 2014 08:39:23 -0700 (PDT) Received: by 10.140.88.81 with HTTP; Thu, 24 Jul 2014 08:39:23 -0700 (PDT) In-Reply-To: References: <21456.19915.45180.915211@gargle.gargle.HOWL> Date: Thu, 24 Jul 2014 17:39:23 +0200 Message-ID: From: Malcolm Matalka To: Fabrice Le Fessant Cc: Raoul Duke , OCaml , Nicolas Boulay Content-Type: multipart/alternative; boundary=001a1137d358d54cee04fef24294 Subject: Re: [Caml-list] concurrent gc? --001a1137d358d54cee04fef24294 Content-Type: text/plain; charset=UTF-8 Cool, what sort of tricks can you do to reduce the number of blocks? Den 24 jul 2014 17:36 skrev "Fabrice Le Fessant" < Fabrice.Le_fessant@inria.fr>: > Note that the cost of the GC does not automatically depends on the size of > RAM. In many networking servers, memory is filled with strings, caching > files on disk or content to be sent on the network. Such cases make OCaml > GC happy, since it does not have to manipulate many objects, and it won't > scan strings for pointers within them. There are also other tricks to > improve the GC behavior: you might want to change the data representation > to decrease the number of blocks in the heap, I used to do it a lot when > doing computations on millions of entries that would not otherwise stay in > memory. > > --Fabrice > > > On Thu, Jul 24, 2014 at 8:58 AM, Nicolas Boulay > wrote: > >> What about server that use ~60GB of RAM ? Todays server are sold with 32 >> to 256 GB of RAM and lot of cpu core. >> Maybe in such extreme cases, offloading the major collection of the GC >> could reduce latency a lot ? >> >> >> 2014-07-24 2:05 GMT+02:00 John F. Carr : >> >> >>> Most programs spend a minority of their time in garbage collection. >>> Even if the new GC thread did not slow down the main program, >>> possible speedup would be less than 2x, probably well under 50%. >>> >>> For technical reasons, offloading major collections in OCaml is easier >>> than offloading minor collections, so the potential benefit is less. >>> >>> > extremely clueless question warning, both generally technically but >>> > also vis-a-vie ocaml specifically: >>> > >>> > so even if ocaml can't so easily be made to support multiple threads >>> > of ocaml code, could the gc be moved off to another thread? so that it >>> > could run on another core. would that be of any benefit? >>> >>> -- >>> Caml-list mailing list. Subscription management and archives: >>> https://sympa.inria.fr/sympa/arc/caml-list >>> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners >>> Bug reports: http://caml.inria.fr/bin/caml-bugs >>> >> >> > > > -- > Fabrice LE FESSANT > Chercheur en Informatique > INRIA Paris Rocquencourt -- OCamlPro > Programming Languages and Distributed Systems > --001a1137d358d54cee04fef24294 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

Cool, what sort of tricks can you do to reduce the number of= blocks?

Den 24 jul 2014 17:36 skrev "Fabrice Le Fes= sant" <Fabrice.Le_fe= ssant@inria.fr>:
Note that the cost of the GC does not automatically depend= s on the size of RAM. In many networking servers, memory is filled with str= ings, caching files on disk or content to be sent on the network. Such case= s make OCaml GC happy, since it does not have to manipulate many objects, a= nd it won't scan strings for pointers within them. There are also other= tricks to improve the GC behavior: you might want to change the data repre= sentation to decrease the number of blocks in the heap, I used to do it a l= ot when doing computations on millions of entries that would not otherwise = stay in memory.

--Fabrice


On Thu, Jul 24, 2014 at 8:58 AM, Nicolas Boulay <= nicolas@boulay.name> wrote:
What about server that= use ~60GB of RAM ? Todays server are sold with 32 to 256 GB of RAM and lot= of cpu core.
Maybe in such extreme cases, offloading the major collection of the G= C could reduce latency a lot ?


201= 4-07-24 2:05 GMT+02:00 John F. Carr <jfc@mit.edu>:


Most programs spend a minority of their time in garbage collection.
Even if the new GC thread did not slow down the main program,
possible speedup would be less than 2x, probably well under 50%.

For technical reasons, offloading major collections in OCaml is easier
than offloading minor collections, so the potential benefit is less.

=C2=A0> extremely clueless question warning, both generally technically = but
=C2=A0> also vis-a-vie ocaml specifically:
=C2=A0>
=C2=A0> so even if ocaml can't so easily be made to support multiple= threads
=C2=A0> of ocaml code, could the gc be moved off to another thread? so t= hat it
=C2=A0> could run on another core. would that be of any benefit?

--
Caml-list mailing list. =C2=A0Subscription management and archives:
ht= tps://sympa.inria.fr/sympa/arc/caml-list
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
Bug reports: http://caml.inria.fr/bin/caml-bugs




--
Fabrice LE F= ESSANT
Chercheur en Informatique
INRIA Paris Rocquencourt -- OCamlPro=
Programming Languages and Distributed Systems
--001a1137d358d54cee04fef24294--