From owner-cvs-src@FreeBSD.ORG  Thu Mar 27 15:05:25 2003
Return-Path: <owner-cvs-src@FreeBSD.ORG>
Delivered-To: cvs-src@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id 501F537B409; Thu, 27 Mar 2003 15:05:25 -0800 (PST)
Received: from flood.ping.uio.no (flood.ping.uio.no [129.240.78.31])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 932C444035; Thu, 27 Mar 2003 14:32:37 -0800 (PST)
	(envelope-from des@ofug.org)
Received: by flood.ping.uio.no (Postfix, from userid 2602)
	id F02725308; Thu, 27 Mar 2003 23:32:35 +0100 (CET)
X-URL: http://www.ofug.org/~des/
X-Disclaimer: The views expressed in this message do not necessarily
  coincide with those of any organisation or company with
  which I am or have been affiliated.
To: David Malone <dwmalone@maths.tcd.ie>
From: des@ofug.org (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=)
Date: Thu, 27 Mar 2003 23:32:35 +0100
In-Reply-To: <20030327212647.GA64029@walton.maths.tcd.ie> (David Malone's
 message of "Thu, 27 Mar 2003 21:26:47 +0000")
Message-ID: <xzpr88sv3ss.fsf@flood.ping.uio.no>
User-Agent: Gnus/5.090015 (Oort Gnus v0.15) Emacs/21.2
References: <Pine.BSF.4.21.0303260956250.27748-100000@root.org>
	<20030326225530.G2075@odysseus.silby.com>
	<20030327180247.D1825@gamplex.bde.org>
	<xzp7kalw5j4.fsf@flood.ping.uio.no>
	<20030327212647.GA64029@walton.maths.tcd.ie>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: quoted-printable
X-Spam-Status: No, hits=-32.1 required=5.0
	tests=AWL,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT,
	      REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_GNUS_UA
	autolearn=ham	version=2.50
X-Spam-Level: 
X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp)
cc: src-committers@FreeBSD.org
cc: Bruce Evans <bde@zeta.org.au>
cc: Nate Lawson <nate@root.org>
cc: cvs-src@FreeBSD.org
cc: Mike Silbersack <silby@silby.com>
cc: cvs-all@FreeBSD.org
Subject: Re: Checksum/copy
X-BeenThere: cvs-src@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: CVS commit messages for the src tree <cvs-src.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src>,
	<mailto:cvs-src-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/cvs-src>
List-Post: <mailto:cvs-src@freebsd.org>
List-Help: <mailto:cvs-src-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src>,
	<mailto:cvs-src-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 27 Mar 2003 23:05:30 -0000

David Malone <dwmalone@maths.tcd.ie> writes:
> On Thu, Mar 27, 2003 at 09:57:35AM +0100, des@ofug.org wrote:
> > Might it be a good idea to have separate b{copy,zero} implementations
> > for special purposes like pmap_{copy,zero}_page?
> We do have a i686_pagezero already, which seems to be used in
> pmap_zero_page - I guess it may not be well tuned to modern processors,
> as it is almost 5 years old.

i686_pagezero uses 'rep stosl' after an initial 'rep scasl' to check
if the page was already zero (which is a pessimization unless we zero
a lot of pages that are already zeroed).  SSE can do far better than
that.

DES
--=20
Dag-Erling Sm=F8rgrav - des@ofug.org