From owner-freebsd-hackers@FreeBSD.ORG Fri Mar 21 01:16:06 2008 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E7635106567B for ; Fri, 21 Mar 2008 01:16:06 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from mail06.syd.optusnet.com.au (mail06.syd.optusnet.com.au [211.29.132.187]) by mx1.freebsd.org (Postfix) with ESMTP id 7030D8FC25 for ; Fri, 21 Mar 2008 01:16:06 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from server.vk2pj.dyndns.org (c220-239-20-82.belrs4.nsw.optusnet.com.au [220.239.20.82]) by mail06.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id m2L1FmBf031875 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 21 Mar 2008 12:15:56 +1100 Received: from server.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1]) by server.vk2pj.dyndns.org (8.14.2/8.14.1) with ESMTP id m2L1FmKF069247; Fri, 21 Mar 2008 12:15:48 +1100 (EST) (envelope-from peter@server.vk2pj.dyndns.org) Received: (from peter@localhost) by server.vk2pj.dyndns.org (8.14.2/8.14.2/Submit) id m2L1FlkM069246; Fri, 21 Mar 2008 12:15:47 +1100 (EST) (envelope-from peter) Date: Fri, 21 Mar 2008 12:15:47 +1100 From: Peter Jeremy To: Chuck Robey Message-ID: <20080321011547.GA69011@server.vk2pj.dyndns.org> References: <47DF1045.6050202@chuckr.org> <20080318082816.GA74218@eos.sc1.parodius.com> <47E146F9.5060105@chuckr.org> <20080319172213.GA28075@eos.sc1.parodius.com> <47E1558A.2030107@chuckr.org> <20080319184244.GA29838@eos.sc1.parodius.com> <47E16514.7090203@chuckr.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="+HP7ph2BbKc20aGI" Content-Disposition: inline In-Reply-To: <47E16514.7090203@chuckr.org> X-PGP-Key: http://members.optusnet.com.au/peterjeremy/pubkey.asc User-Agent: Mutt/1.5.17 (2007-11-01) Cc: FreeBSD-Hackers Subject: Re: remote operation or admin X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 21 Mar 2008 01:16:07 -0000 --+HP7ph2BbKc20aGI Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Mar 19, 2008 at 03:10:12PM -0400, Chuck Robey wrote: >it might be possible to find some way to extend the work domain of an smp >system to stretch across machine lines, to jump across motherboards. Maybe >not to be global (huge latencies scare me away), but what about just going >3 feet, on a very high speed bus, like maybe a private pci bus? Not what >is, what could be? This is definitely possible. DEC built a memory channel adapter which allowed multiple AlphaServers to share (part of) each other's RAM. You could also try looking at Amoeba - it is a cross between a "traditional" SMP system and a cluster. There's probably no reason why you couldn't build a kernel module to "share" RAM between hosts using Ethernet or similar - though it would be much slower than accessing local RAM. >small, but with a bunch of bandwidth. So, in that case, what really are >the differences between smp and clustering, besides the raw current size of >the implementation? Are there huge basic differences between the >clustering concept and by smp's actual tasks? The access time differences between local and remote RAM mean that there are different trade-offs: Memory coherence is extremely expensive so more effort is expended in avoiding operations that require coherence. In general tasks that work well in a clustered environment have very low inter-process communication requirements. --=20 Peter Jeremy Please excuse any delays as the result of my ISP's inability to implement an MTA that is either RFC2821-compliant or matches their claimed behaviour. --+HP7ph2BbKc20aGI Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.8 (FreeBSD) iEYEARECAAYFAkfjDEMACgkQ/opHv/APuIc65wCfcgbQTBbiTKgRbozJmTkYRDho WzMAn1stcC68WpWWqu57rBMkNXSOReHl =CQEP -----END PGP SIGNATURE----- --+HP7ph2BbKc20aGI--