From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail3-relais-sop.national.inria.fr (mail3-relais-sop.national.inria.fr [192.134.164.104]) by walapai.inria.fr (8.13.6/8.13.6) with ESMTP id p3NDmRIn007967 for ; Sat, 23 Apr 2011 15:48:27 +0200 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AroBAGjYsk3RVdQ2kGdsb2JhbAClYAgUAQEBAQkJDQcUBCGIcJ5WiniCJ4QLNIheAQEDBoVwBI41hAiBBoUEOg X-IronPort-AV: E=Sophos;i="4.64,258,1301868000"; d="scan'208";a="81584985" Received: from mail-vw0-f54.google.com ([209.85.212.54]) by mail3-smtp-sop.national.inria.fr with ESMTP/TLS/RC4-SHA; 23 Apr 2011 15:47:51 +0200 Received: by vws18 with SMTP id 18so1935513vws.27 for ; Sat, 23 Apr 2011 06:47:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:subject:mime-version:content-type:from :in-reply-to:date:cc:content-transfer-encoding:message-id:references :to:x-mailer; bh=896MH3DfgY15F1Ys4I5ZZZzTaqJgQ+GOEkYSoeC2VxU=; b=qsy7KyQwPoSfxLbj3T5osB/s1Nj1TIfTlPOsIYDmhQNnOHrAe7SldL/ZfVhZIOX27P K+RBWcQtGAoGeYteE2ZEpm3JnrBSKpki49b1XBBVJGethVwuAapHstInJK+C309uI+ss aK6soHGb0pkZ2usiFhkU5Y+1rFCwI4MhiqO5E= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:mime-version:content-type:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to:x-mailer; b=Z3IB/+eilHHVD6lZKdZj4JnPTHqIIQRX+cGjViDyfsCpvyAmkoCWRq5vLnDTsRwHUZ 2Fseh16aIWIcIG7rrNpM73CwAtbWhrrXwfkfoPLqaM9+Og13KooaVxF5hSiF53LLaMYx pt48iJxwCZsHSfaf9FNXMnVwYbkrA90fsibBw= Received: by 10.52.113.193 with SMTP id ja1mr3251709vdb.183.1303566470611; Sat, 23 Apr 2011 06:47:50 -0700 (PDT) Received: from [192.168.0.100] (216-107-215-230.KishHeaterRoad.nhvt.static.cust.seg.net [216.107.215.230]) by mx.google.com with ESMTPS id 15sm700247vdh.27.2011.04.23.06.47.44 (version=TLSv1/SSLv3 cipher=OTHER); Sat, 23 Apr 2011 06:47:49 -0700 (PDT) Mime-Version: 1.0 (Apple Message framework v1082) Content-Type: text/plain; charset=us-ascii From: Alexy Khrabrov In-Reply-To: Date: Sat, 23 Apr 2011 09:47:32 -0400 Cc: Caml List Message-Id: <97D08229-2871-42F1-A50D-8E85C6C2BE31@gmail.com> References: <76544177.594058.1303341821437.JavaMail.root@zmbs4.inria.fr> <4DAFE141.7080003@inria.fr> <4DAFF442.8000806@lexifi.com> <799994864.610698.1303412613509.JavaMail.root@zmbs4.inria.fr> <4DB136FB.6050302@inria.fr> <1303463512.8429.1344.camel@thinkpad> To: Eray Ozkural X-Mailer: Apple Mail (2.1082) Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by walapai.inria.fr id p3NDmRIn007967 Subject: Re: [Caml-list] Efficient OCaml multicore -- roadmap? On Apr 23, 2011, at 6:17 AM, Eray Ozkural wrote: > I don't really care what others say, but to prove that this has any performance value you should do the following: > > > Compare your most "parallel" algorithm with the performance of a corresponding well-written MPI application using openmpi's shared memory transport. If there is a difference, then your system has some value. > > Of course openmpi's shared memory transport is terribly buggy, but it should give a baseline acceptable performance. > > If there is no comparison, we have no idea. The problem with "implement in MPI and compare" is that you have to rearchitect a sequential program for a totally different model. By contrast, using shared memory parallelism, it's often a question of using pmap. I really recommend everybody interested in parallelism to learn and try Clojure on a small problem. You can replace a single map by pmap in a suitable setting and observe a not-quite-linear, but proportional speedup. I'd be really happy if OCaml gets the mechanisms from Clojure. -- Alexy