From owner-freebsd-isdn Tue Dec 15 04:44:21 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id EAA24348 for freebsd-isdn-outgoing; Tue, 15 Dec 1998 04:44:21 -0800 (PST) (envelope-from owner-freebsd-isdn@FreeBSD.ORG) Received: from eharz001.nortel.co.uk (eharz001.nortel.co.uk [192.100.101.15]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id EAA24343 for ; Tue, 15 Dec 1998 04:44:20 -0800 (PST) (envelope-from barry.scott.tsbarry@nortel.co.uk) Received: from bhars221.europe.nortel.com (actually eharg1e1.nortel.co.uk) by eharz001.nortel.co.uk with SMTP (PP); Tue, 15 Dec 1998 12:47:18 +0000 Received: from nnsgifd1.europe.nortel.com by bhars221.europe.nortel.com with SMTP (PP); Tue, 15 Dec 1998 12:39:47 +0000 Received: by nnsgifd1.europe.nortel.com with Internet Mail Service (5.0.1460.8) id ; Tue, 15 Dec 1998 12:41:32 -0000 Message-ID: <81C8165DD2A7D111AD700000F81F29CB025049E7@nwcwi19.europe.nortel.com> From: "Scott, Barry [MDN05:7E26:EXCH]" To: freebsd-isdn@FreeBSD.ORG Subject: RE: streams implementations Date: Tue, 15 Dec 1998 12:41:29 -0000 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.0.1460.8) Content-Type: text/plain; charset="iso-8859-1" Sender: owner-freebsd-isdn@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Jonathan M. Bresler [jmb@FreeBSD.ORG] said. > the idea of streams is wonderful, the realization is costly. each > layer added (or module pushed) slows down processing and hurts > roughput. ritchie developed streams for serial, if i remember > correctly. streams was then applied to networks. there is an RFC > about layering being bad for networking and the relative performance > of NIT vs BPF prove the case. At DEC we used a comms exec called LES (Layered environment services) that allowed a web of nodes to be connected. The VAX PSI and DEC NIS routers and parts of DECnet Phase V where LES implemented comms. LES ran inside the VAX/VMS OS and in embeded systems like the routers. For design and debug LES ran in user mode simulation. The performance was better then direct call between layers. And having clean OO like seperatation of layers and (literally) message passing made implementation fast. Stream (the concept) can be implemented as a very light weight mechanism. Of course we passed buffers around not individual bytes. And used very smart buffer management. BArry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message