Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!lll-lcc!styx!ames!ucbcad!ucbvax!BIONET-20.ARPA!ROODE From: ROODE@BIONET-20.ARPA (David Roode) Newsgroups: comp.protocols.tcp-ip Subject: Re: Ethernet Terminal Concentrators Message-ID: <12300570707.26.ROODE@BIONET-20.ARPA> Date: Thu, 7-May-87 18:52:57 EDT Article-I.D.: BIONET-2.12300570707.26.ROODE Posted: Thu May 7 18:52:57 1987 Date-Received: Sat, 9-May-87 09:52:22 EDT References: Sender: daemon@ucbvax.BERKELEY.EDU Distribution: world Organization: The ARPA Internet Lines: 20 The numbers you quote are extremely similar to those sent by David Kashtan over a year ago concerning the affect of context switching on performance of Telnet service. Kashtan is the implementor of a package which includes IP and TCP and TELNET and which has now become available from SRI International. This package has been in existence for a very long time, and his previous message, if memory serves me, concerned some experiments he did with a non-Kernel implementation of the above protocols. The problem is that the CPU can be consumed by the context switching needed for character at a time I/O as common in Telnet. Kashtan's experience was that a single 9600 baud Telnet connection could consume nearly an entire 780. Again, this is subject to my recall. However, his implementation handles things very differently and runs in Kernel mode. As a result it is much more efficient. We have it here on MicroVaxes and it is the primary means for users to use the machine, i.e. there are no hardwire terminal ports to speak of, so everyone comes in via cisco boxes. We note no problems with the Telnet connections to the microvax consuming excess resources, although we typically only have 6-8 at a time of peak usage. -------