From owner-freebsd-hackers@FreeBSD.ORG  Mon Feb 16 14:23:22 2004
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id E5D1516A4CE
	for <freebsd-hackers@freebsd.org>;
	Mon, 16 Feb 2004 14:23:22 -0800 (PST)
Received: from newman.gte.com (newman.gte.com [132.197.8.26])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 8ABAE43D1D
	for <freebsd-hackers@freebsd.org>;
	Mon, 16 Feb 2004 14:23:22 -0800 (PST)	(envelope-from ak03@gte.com)
Received: from h132-197-179-27.gte.com (kanpc.gte.com [132.197.179.27])
	by newman.gte.com (8.9.1/8.9.1) with ESMTP id RAA01722;
	Mon, 16 Feb 2004 17:23:21 -0500 (EST)
Received: from kanpc.gte.com (localhost [IPv6:::1])i1GMNIed011846;
	Mon, 16 Feb 2004 17:23:18 -0500 (EST)	(envelope-from ak03@gte.com)
Date: Mon, 16 Feb 2004 17:23:18 -0500
From: Alexander Kabaev <ak03@gte.com>
To: "Juan Tumani" <jtumani55@hotmail.com>
Message-Id: <20040216172318.4b76daa2@kanpc.gte.com>
In-Reply-To: <BAY12-F541stYkcOj3i00018525@hotmail.com>
References: <BAY12-F541stYkcOj3i00018525@hotmail.com>
Organization: Verizon Data Services
X-Mailer: Sylpheed version 0.9.8claws23 (GTK+ 1.2.10; i386-portbld-freebsd5.2)
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
cc: des@des.no
cc: freebsd-hackers@freebsd.org
Subject: Re: FreeBSD 5.2 v/s FreeBSD 4.9 MFLOPS performance
 (gcc3.3.3v/sgcc2.9.5)
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 16 Feb 2004 22:23:23 -0000

On Mon, 16 Feb 2004 16:36:35 -0500
"Juan Tumani" <jtumani55@hotmail.com> wrote:

> Thanks Matt for picking up on the linker problem.  Patching the kernel
> would, to me, be masking the real problem.
> 
> What other "improvements" does gcc333 have over gcc295 that might
> explain why it's linked products run in a half-fast mode (take twice+
> as long)?
> 
> JT
> 
> 
> >From: Matthew Dillon <dillon@apollo.backplane.com>
> >To: "Juan Tumani" <jtumani55@hotmail.com>
> >CC: des@des.no, freebsd-hackers@freebsd.org
> >Subject: Re: FreeBSD 5.2 v/s FreeBSD 4.9 MFLOPS performance 
> >(gcc3.3.3v/sgcc2.9.5)
> >Date: Mon, 16 Feb 2004 13:12:15 -0800 (PST)
> >
> >     I'm surprised Bruce hasn't chimed in here yet.  I guess he's
> >     tired of repeating himself.
> >
> >     In 4.9, libcsu, which generates crt1.o (which is the start code
> >     for C programs which the linker links in automatically) has this
> >     line in 
> >it:
> >
> >	    andl    $~0xf, %%esp            # align stack to 16-byte
> >	    boundary
> >
> >     So anything linked with 4.9 is going to align the stack on a
> >     16 byte boundary no matter WHAT the kernel does.
> >
> >     FreeBSD-5 does not have this alignment in its crt1.o because
> >     GCC3 automatically aligns the stack on a per-procedure basis. 
> >     Or at least it is supposed to.  Maybe it's broke?  :-)
> >
> >						-Matt
> >
Quite possibly. I run the same test using the latest GCC snapshot
configured as system compiler and did not see such a massive slowdown.
GCC 3.3.3 wins slightly on most tests and loses only on module #2 of the
flops.c program posted here. 

-- 
Alexander Kabaev