From owner-freebsd-hackers@FreeBSD.ORG Mon Mar 10 09:59:00 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 5DE3C106566C; Mon, 10 Mar 2008 09:59:00 +0000 (UTC) (envelope-from alexander@leidinger.net) Received: from redbull.bpaserver.net (redbullneu.bpaserver.net [213.198.78.217]) by mx1.freebsd.org (Postfix) with ESMTP id 2A4378FC13; Mon, 10 Mar 2008 09:59:00 +0000 (UTC) (envelope-from alexander@leidinger.net) Received: from outgoing.leidinger.net (p54A54F51.dip.t-dialin.net [84.165.79.81]) by redbull.bpaserver.net (Postfix) with ESMTP id EBFB02E27E; Mon, 10 Mar 2008 10:58:53 +0100 (CET) Received: from webmail.leidinger.net (webmail.leidinger.net [192.168.1.102]) by outgoing.leidinger.net (Postfix) with ESMTP id DFBCE940A1; Mon, 10 Mar 2008 10:57:28 +0100 (CET) Received: (from www@localhost) by webmail.leidinger.net (8.14.2/8.13.8/Submit) id m2A9vRCW036923; Mon, 10 Mar 2008 10:57:27 +0100 (CET) (envelope-from Alexander@Leidinger.net) Received: from pslux.cec.eu.int (pslux.cec.eu.int [158.169.9.14]) by webmail.leidinger.net (Horde MIME library) with HTTP; Mon, 10 Mar 2008 10:57:27 +0100 Message-ID: <20080310105727.ah4y31sh40o04gw4@webmail.leidinger.net> X-Priority: 3 (Normal) Date: Mon, 10 Mar 2008 10:57:27 +0100 From: Alexander Leidinger To: Julian Elischer References: <200803081133.02575.hselasky@c2i.net> <20080308171435.J88526@fledge.watson.org> <200803091027.39843.hselasky@c2i.net> <47D41160.9070901@elischer.org> In-Reply-To: <47D41160.9070901@elischer.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; DelSp="Yes"; format="flowed" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable User-Agent: Internet Messaging Program (IMP) H3 (4.1.5) / FreeBSD-8.0 X-BPAnet-MailScanner-Information: Please contact the ISP for more information X-BPAnet-MailScanner: Found to be clean X-BPAnet-MailScanner-SpamCheck: not spam, SpamAssassin (not cached, score=-12.71, required 6, BAYES_00 -15.00, MIME_QP_LONG_LINE 1.40, RDNS_DYNAMIC 0.10, SARE_LWSHORTT 0.79) X-BPAnet-MailScanner-From: alexander@leidinger.net X-Spam-Status: No X-Mailman-Approved-At: Mon, 10 Mar 2008 11:28:25 +0000 Cc: freebsd-hackers@freebsd.org, Robert Watson , Hans Petter Selasky Subject: Re: Documentation on writing a custom socket 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: Mon, 10 Mar 2008 09:59:00 -0000 Quoting Julian Elischer (from Sun, 09 Mar 2008 =20 09:33:36 -0700): > Hans Petter Selasky wrote: >> On Saturday 08 March 2008, Robert Watson wrote: >>> On Sat, 8 Mar 2008, Hans Petter Selasky wrote: >> >>> For example, do you >>> anticipate using or even needing the routing facilities, and how might y= ou >>> map ISDN telephony parts into the normal network stack infrastructure of >>> addresses, routing, interfaces, etc? >> >> Hi Robert, >> >> ISDN is very simple. In the ISDN world there is a term called TEI =20 >> which is the Terminal Entity Identifier. This kind of like an IP =20 >> address. >> >> Besides from the signalling there are 2 B-channels which can =20 >> transport data or audio. One of my goals is to achive zero copy =20 >> when moving data to/from an ISDN line and also in combination to =20 >> Voice over IP. Currently data is moved through userland (Asterisk =20 >> typically) which is usable in the short term, but in the long run I =20 >> want this extra copying removed. The idea is that I can route [IP] =20 >> packets (mbufs) through various filters in the kernel without the =20 >> need for copy. > > Given the speed of ISDN connections, It is not worth doing zero copy > on ISDN unless you have more than 1000 of them, which seems unlikely. > given a total throughput of 128000 b/s and the speed of current > hardware, the number of packets per second is probably not high > enough to make the difference even noticable. What about low-power embedded systems and a high count of small =20 packets (VoIP)? Where do you draw the line between powerful enough and =20 how do you chose this line? Bye, Alexander. --=20 http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID =3D B0063FE7 http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID =3D 72077137