From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mail4-relais-sop.national.inria.fr (mail4-relais-sop.national.inria.fr [192.134.164.105])
	by walapai.inria.fr (8.13.6/8.13.6) with ESMTP id p7P82hlO011827
	for <caml-list@sympa-roc.inria.fr>; Thu, 25 Aug 2011 10:02:43 +0200
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: AoABADUBVk7RVaE2kGdsb2JhbABDFqdjCBQBAQEBCQkNBxQEIYFAAQEBAQEBARICJgYBATcBBAsLDiYSNAEFARwGNYdPAgKcTwqPDgGOPQWFbF+feTyDZQ
X-IronPort-AV: E=Sophos;i="4.68,279,1312149600"; 
   d="scan'208";a="106560502"
Received: from mail-fx0-f54.google.com ([209.85.161.54])
  by mail4-smtp-sop.national.inria.fr with ESMTP/TLS/RC4-SHA; 25 Aug 2011 10:02:41 +0200
Received: by fxe4 with SMTP id 4so2941503fxe.27
        for <caml-list@inria.fr>; Thu, 25 Aug 2011 01:02:41 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=googlemail.com; s=gamma;
        h=subject:mime-version:content-type:from:in-reply-to:date:cc
         :content-transfer-encoding:message-id:references:to:x-mailer;
        bh=t42XXEtfgrbW+Z/IUwsMVObmQTE0l/O8wMrsWo2yNAc=;
        b=YIS/5fANiUgqJQi2ba9MKE65wv92BawIbUth9rBB1whc1byt8f7e4ASbKsKke/P++p
         tDMXW5lBLpg7ds5hwuE6EKUjpKbyYwfB9XmUVbVJ2qtx6qy0T1F9rhgskkGZSMM2QKSj
         VwrpmvQMPvWt92XFv9Hz9vuXWZyFLjC5hhvJU=
Received: by 10.223.16.210 with SMTP id p18mr8722820faa.71.1314259361116;
        Thu, 25 Aug 2011 01:02:41 -0700 (PDT)
Received: from coruscant.kosmos.all (ip-95-223-170-32.unitymediagroup.de [95.223.170.32])
        by mx.google.com with ESMTPS id b13sm268870fak.40.2011.08.25.01.02.38
        (version=SSLv3 cipher=OTHER);
        Thu, 25 Aug 2011 01:02:39 -0700 (PDT)
Mime-Version: 1.0 (Apple Message framework v1244.3)
Content-Type: text/plain; charset=us-ascii
From: Benedikt Meurer <benedikt.meurer@googlemail.com>
In-Reply-To: <1314218451.3496.42.camel@thinkpad>
Date: Thu, 25 Aug 2011 10:02:39 +0200
Cc: caml-list@inria.fr
Message-Id: <11577B43-4270-4BA4-AA77-7FDEFB4B563B@googlemail.com>
References: <93199F3B-E9CF-4D93-9B2B-BAAB03F4FC08@googlemail.com> <CAPFanBGk8gCmVKFVh4bPZyy8LjoTf9dzVWZsNgrEut=POtM=Pw@mail.gmail.com> <4EF51F29-D437-4F6F-9C91-DBEA3D4C3EB8@googlemail.com> <1314218451.3496.42.camel@thinkpad>
To: Gerd Stolpmann <info@gerd-stolpmann.de>
X-Mailer: Apple Mail (2.1244.3)
Content-Transfer-Encoding: 8bit
X-MIME-Autoconverted: from quoted-printable to 8bit by walapai.inria.fr id p7P82hlO011827
Subject: Re: [Caml-list] Linear Scan Register Allocator for ocamlopt/ocamlnat


On Aug 24, 2011, at 22:40 , Gerd Stolpmann wrote:

>>> - the performance cost of this new allocator in the generated code? I
>>> suppose the results may vary between different architectures (eg. x86
>>> is probably more sensitive to good allocation decisions than x86_64).
>> 
>> - http://ps.informatik.uni-siegen.de/~meurer/tmp/compiletime_timings.pdf contains a comparison of the ocamlopt invocations.
>> - http://ps.informatik.uni-siegen.de/~meurer/tmp/runtime_timings.pdf contains comparison of the generated code.
>> 
>> As can be seen from the results, amd64 is more sensitive to register allocator changes than i386. 
> 
> Well, this particular i386 CPU model is a strange guy - Northwoods have
> this extremely long pipeline, which is very sensitive to unforeseen
> jumps. It would be more interesting to see this test on a modern CPU in
> i386 mode. My guess is that it behaves then more like amd64.

Modern CPUs most probably don't run ocaml in 32bit mode, but more likely in long mode. That's why we choose to run the i386 on "real 32bit hardware", where the ocaml i386 port is actually used.

I'll rerun the benchmark in 32bit mode on a modern cpu to see how things change.

> Gerd

Benedikt