From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1LkG5J-0001xo-Ah
	for qemu-devel@nongnu.org; Thu, 19 Mar 2009 07:06:49 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1LkG5J-0001xc-1u
	for qemu-devel@nongnu.org; Thu, 19 Mar 2009 07:06:49 -0400
Received: from [199.232.76.173] (port=50624 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1LkG5I-0001xY-Rk
	for qemu-devel@nongnu.org; Thu, 19 Mar 2009 07:06:48 -0400
Received: from fg-out-1718.google.com ([72.14.220.155]:6233)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <laurent.desnogues@gmail.com>) id 1LkG5I-0005bI-E8
	for qemu-devel@nongnu.org; Thu, 19 Mar 2009 07:06:48 -0400
Received: by fg-out-1718.google.com with SMTP id e21so37358fga.8
	for <qemu-devel@nongnu.org>; Thu, 19 Mar 2009 04:06:47 -0700 (PDT)
MIME-Version: 1.0
In-Reply-To: <gpt7c5$2v2$1@ger.gmane.org>
References: <gpo05k$6u4$1@ger.gmane.org> <49BF8A5B.7070706@siemens.com>
	<gpo56s$o1f$1@ger.gmane.org>
	<200903171251.41148.paul@codesourcery.com>
	<gpt5ht$utu$1@ger.gmane.org>
	<761ea48b0903190330j663a388akf65fb78b9579ddb9@mail.gmail.com>
	<gpt7c5$2v2$1@ger.gmane.org>
Date: Thu, 19 Mar 2009 12:06:47 +0100
Message-ID: <761ea48b0903190406u53bbd856u5a3a8b3f34ae6b0a@mail.gmail.com>
Subject: Re: [Qemu-devel] Re: branches are expensive
From: Laurent Desnogues <laurent.desnogues@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Reply-To: qemu-devel@nongnu.org
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: qemu-devel@nongnu.org

On Thu, Mar 19, 2009 at 11:39 AM, Steffen Liebergeld <usenet@gmx.eu> wrote:
> Laurent Desnogues <laurent.desnogues@gmail.com> schrieb:
>> On Thu, Mar 19, 2009 at 11:07 AM, Steffen Liebergeld <usenet@gmx.eu> wro=
te:
>>>
>>> I've tested Qemu 0.10.0 and with i386-softmmu on a i386 host I get the
>>> following numbers:
>>> direct jump count 70%, 2 jumps 54%
>>>
>>> For qemu-system-arm on an ARM host, the numbers look like this:
>>> direct jump count 47%, 2 jumps 40%
>>>
>>> For completeness I tested qemu-system-arm on a i386 host as well:
>>> direct jump count 44%, 2 jumps 37%
>>>
>>> So it looks like the chaining on ARM targets is not as effective as on =
i386
>>> targets (regardless of the guest, I used the same guest setup, compiled=
 for
>>> different architectures, on all tests). Do you have any ideas why this =
is the
>>> case?
>>
>> Different instruction sets, different compilers. =A0You'd better compare
>> guest code before drawing any conclusion.
>
> The qemu-system-arm on ARM and i386 were compiled by the same compiler.

I said "guest" not "host" :)

You need to compare ARM and i386 blocks *before* translation.


Laurent