From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail4-relais-sop.national.inria.fr (mail4-relais-sop.national.inria.fr [192.134.164.105]) by yquem.inria.fr (Postfix) with ESMTP id C809BBBB7 for ; Sun, 13 Jul 2008 01:05:33 +0200 (CEST) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AisFAAPVeEjRVZKyY2dsb2JhbACRajkaBB4DkQ6FDg X-IronPort-AV: E=Sophos;i="4.30,351,1212357600"; d="scan'208";a="27271852" Received: from wa-out-1112.google.com ([209.85.146.178]) by mail4-smtp-sop.national.inria.fr with ESMTP; 13 Jul 2008 01:05:32 +0200 Received: by wa-out-1112.google.com with SMTP id j4so2359924wah.3 for ; Sat, 12 Jul 2008 16:05:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=Mj47T1KMMEw+9/yYTx9Fx0uYRwt942n4VeFK4QGuQaU=; b=XtK3dSr1BV5U0BhNGNMEh1/oaeRRj/DnkshKtipJXOXQnsNpvd02W7ejRRaeAQGRxq IhSKqYGpoOQifH3/WVdM4XdAO92nPuAvtP5x4upPVCMslWNz7P/1OlXveVFESH34Il5v jlL2BgKndW7OMlw+mFRHphmjs9SAxCPhgZ9Lo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=wRCr211GmLnRBv2AqOyBIP7f7/gtjkz2GaE8IqI8z/XwBcBmkwhJXgYbnV5EPGP1uE LwT2a+ipRq0DiA2GIbkzFLjbvrEPlxYDdo/qXGPJHAo3FDg/nfJiX9c0J+7SPP6PTFVn Oqn9jkrI5i76uZ/g9T03ZhSguxZQejtsNDs/w= Received: by 10.114.171.1 with SMTP id t1mr2974957wae.120.1215903931141; Sat, 12 Jul 2008 16:05:31 -0700 (PDT) Received: by 10.114.147.12 with HTTP; Sat, 12 Jul 2008 16:05:31 -0700 (PDT) Message-ID: Date: Sat, 12 Jul 2008 16:05:31 -0700 From: "J C" To: caml-list@yquem.inria.fr Subject: Re: [Caml-list] thousands of CPU cores In-Reply-To: <487768E2.6000108@inria.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <487768E2.6000108@inria.fr> X-Spam: no; 0.00; model:01 mutable:01 jhc:98 0033:98 wrote:01 caml-list:01 slower:02 programming:03 programming:03 concurrency:04 perhaps:05 fri:05 jul:05 shared:06 xavier:06 On Fri, Jul 11, 2008 at 7:06 AM, Xavier Leroy wrote: > Look at GPUs, which are the closest we have > today to a manycore system: 128 cores are available today, more is > in preparation, but the programming model is definitely not SMP. I was reading an article about CUDA written by an in-the-trenches GPGPU programmer. I can't find it now, but one of the points of the article, as I understood it, was that stream-oriented approaches (like BrookGPU) look great in theory, but don't work very well in practice - they can often be orders of magnitude slower than "dirty" approaches that use some mutable shared memory block in the video card. In other words, pure-functional programming for multi-core concurrency is just a speculative promise (for academic funding purposes perhaps). (If this sounds familiar and anyone has the link, please post)