From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on yquem.inria.fr X-Spam-Level: * X-Spam-Status: No, score=1.2 required=5.0 tests=AWL,SPF_NEUTRAL autolearn=disabled version=3.1.3 X-Original-To: caml-list@yquem.inria.fr Delivered-To: caml-list@yquem.inria.fr Received: from discorde.inria.fr (discorde.inria.fr [192.93.2.38]) by yquem.inria.fr (Postfix) with ESMTP id 54F46BC69 for ; Mon, 23 Apr 2007 22:13:16 +0200 (CEST) Received: from ug-out-1314.google.com (ug-out-1314.google.com [66.249.92.174]) by discorde.inria.fr (8.13.6/8.13.6) with ESMTP id l3NKDFm2024560 for ; Mon, 23 Apr 2007 22:13:16 +0200 Received: by ug-out-1314.google.com with SMTP id k3so22464ugf for ; Mon, 23 Apr 2007 13:13:15 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=YvKGxtnjefoGK4U6v3UOzcwPD9ZxsGlaXsFd36sUKiB5wYdhlpOeaiFZlKs9N9nizGlhY2kNaLbwn0egMbLo6Ltup7z+9Wj22D9KDRGl8LUZTXzfRzX2JTv/xYEwlA2DAX9c3cezdJmi1Z/LA2UXLE+A5dHBdY+Tk4RLQqIhg6Y= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=p98bOrDk0fUxlDhhxmDncut9WmTXldw0IGtxS4uizb2gmWibWs8icRN7WTg4nw/K2nHjfyrtNP20JEDzPAnJaCsueBI3Eog04Eq9yKC9M+paW1h8HoBjn2SlgzGrlYt3BqEjkugh+vIHDBJ6QNyYrTmpT6rJqW7d68CzfUW3FXI= Received: by 10.78.165.16 with SMTP id n16mr442243hue.1177359191718; Mon, 23 Apr 2007 13:13:11 -0700 (PDT) Received: by 10.78.16.3 with HTTP; Mon, 23 Apr 2007 13:13:11 -0700 (PDT) Message-ID: Date: Mon, 23 Apr 2007 16:13:11 -0400 From: "Markus Mottl" To: ocaml Subject: Re: [Caml-list] Slow allocations with 64bit code? Cc: "yaron jane" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <462B37A0.4050205@inria.fr> X-j-chkmail-Score: MSGID : 462D135B.000 on discorde : j-chkmail score : X : 0/20 1 0.000 -> 1 X-Miltered: at discorde with ID 462D135B.000 by Joe's j-chkmail (http://j-chkmail . ensmp . fr)! X-Spam: no; 0.00; markus:01 mottl:01 markus:01 mottl:01 allocations:01 timings:01 low-level:01 ocaml:01 wrote:01 wrote:01 slower:01 caml-list:01 seems:03 optimized:04 compiled:04 On 4/22/07, Markus Mottl wrote: > On 4/22/07, Xavier Leroy wrote: > > Be careful with timings: I've seen simple changes in code placement > > (e.g. introducing or removing dead code) cause performance differences > > in excess of 20%. It's an unfortunate fact of today's processors that > > their performance is very hard to predict. After performing many extensive tests between 32bit/64bit platforms, it seems that indeed code placement is a major cause of many if not most timing differences I have seen, especially if the difference is unusually big. Other developers who want to make their code run fast independent of platform should therefore be cautioned that a program compiled for different architectures may be slower/faster for very random reasons that have nothing to do with not having optimized well enough for the special case. This is especially true for low-level code, where such effects do not cancel each other out easily. Regards, Markus -- Markus Mottl http://www.ocaml.info markus.mottl@gmail.com