100 \s+2Interim Report on Operating Systems Research in the DASH and Berkeley UNIX Projects\s-2 October 1, 1988 - December 31, 1988 Susan L. Graham Domenico Ferrari David P. Anderson Marshall Kirk McKusick Michael J. Karels Keith Sklower

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\s+2DASH Project\s0 .pp Since September, 1988 the main research direction of the DASH project has been integrated multimedia network communication (i.e., the ability to redirect streams of digital audio/video between I/O devices, processes, hosts, and permanent storage). To this end, we designed an IPC abstraction called "channels" which (unlike datagrams and virtual circuits) has performance, reliability, and security parameters. This has spawned three research efforts: 1) the design of a protocol hierarchy that uses channel parameters to eliminate or optimize protocol functions such as flow control, checksumming and encryption; 2) the design of an OS kernel that uses channel parameters to optimally schedule local resources such as CPU time, buffers space, and network transmission order; 3) the design of algorithms for implementing channels (channel establishment and packet switching) in large networks. .pp The implementation of the DASH kernel has progressed significantly. The major kernel components (virtual memory, network communication, multiprocessor deadline scheduling) are now working. The DASH kernel was ported to the Sequent Symmetry this fall.

\s+2Berkeley UNIX Project\s0 .pp During this period of time we finished implementing and testing a routing table lookup algorithm suggested by Van Jacobsen which may greatly speed up any system acting as a packet switch for CLNP packets. .pp We redesigned, implemented and tested a new interface for communicating routing information between a user level process and the kernel, by means of a special type of message based socket. .pp The results of the additional performance experiments done by Van Jacobson of the Lawrence Berkeley Laboratory, and several additional performance improvements reported in the last quarter have been merged into the Berkeley TCP. .pp We are continuing our participation in the IEEE P1003 standardization efforts for portable operating systems, with particular attention to networking. We are continuing to convert the Berkeley UNIX system to comply with the P1003.1 (POSIX) standard. The POSIX terminal interface and job control mechanism are now fully operational, and are in daily use on our development system.