From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-return-71438-listarch-gcc=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 6414 invoked by alias); 4 Apr 2003 14:51:17 -0000
Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Archive: <http://gcc.gnu.org/ml/gcc/>
List-Post: <mailto:gcc@gcc.gnu.org>
List-Help: <http://gcc.gnu.org/ml/>
Sender: gcc-owner@gcc.gnu.org
Received: (qmail 6407 invoked from network); 4 Apr 2003 14:51:17 -0000
Received: from unknown (HELO mta8.srv.hcvlny.cv.net) (167.206.5.23)
  by sources.redhat.com with SMTP; 4 Apr 2003 14:51:17 -0000
Received: from asv20.srv.hcvlny.cv.net
 (asv20.srv.hcvlny.cv.net [167.206.5.174]) by mta8.srv.hcvlny.cv.net
 (iPlanet Messaging Server 5.2 HotFix 1.14 (built Mar 18 2003))
 with ESMTP id <0HCT008KFQKTF0@mta8.srv.hcvlny.cv.net> for gcc@gcc.gnu.org;
 Fri, 04 Apr 2003 09:50:53 -0500 (EST)
Received: from tiamat (ool-182c9efb.dyn.optonline.net [24.44.158.251])
	by asv20.srv.hcvlny.cv.net (8.12.8/8.12.8) with ESMTP id h34EnnHU021695	for
 <gcc@gcc.gnu.org>; Fri, 04 Apr 2003 09:49:49 -0500 (EST)
Received: from jlquinn by tiamat with local (Exim 3.35 #1 (Debian))
	id 191SV3-0008Ef-00	for <gcc@gcc.gnu.org>; Fri, 04 Apr 2003 09:49:01 -0500
Date: Fri, 04 Apr 2003 17:13:00 -0000
From: Jerry Quinn <jlquinn@optonline.net>
Subject: Re: Slow memcmp for aligned strings on Pentium 3
To: gcc@gcc.gnu.org
Message-id: <E191SV3-0008Ef-00@tiamat>
Content-transfer-encoding: 7BIT
X-SW-Source: 2003-04/txt/msg00181.txt.bz2

I just tried the same benchmark on a Pentium 4 out of curiosity.  Slightly
different results:

Memory compare int:
  10000
  130000
  Speed up: 0.076923
Memory compare 15 bytes:
  10000
  370000
  Speed up: 0.027027
Memory compare 16 bytes:
  20000
  330000
  Speed up: 0.060606
Memory compare 64 bytes:
  10000
  1040000
  Speed up: 0.009615
Memory compare 256 bytes:
  20000
  2300000
  Speed up: 0.008696


Perhaps this is to be expected since the routine uses shifts.

Jerry Quinn