Date: Tue, 26 Nov 1996 00:22:00 GMT Server: NCSA/1.4.2 Content-type: text/html Last-modified: Sat, 23 Nov 1996 01:17:07 GMT Content-length: 2366
LRP is a new network subsystem architecture based on Lazy Receiver Processing. LRP is motivated by the poor performance that interrupt-driven network subsystems show under heavy load. Such systems give strictly highest priority to packet processing and do not correctly account for resources consumed during protocol processing. Under conditions of heavy network load , this leads to unfair allocation of system resources, scheduling anomalies, and livelock.
LRP properly integrates network processing with the operating system's resource allocation scheme. The resources spent in protocol processing are accounted for and charged to the application on whose behalf this processing is performed. The system combines early packet demultiplexing, early discard of excess packets, and a lazy processing model, where packet processing is performed at the receiver's priority and just in time to avoid delaying the receiving application. This enables the system to provide stable overload behaviour, fair resource allocation, and increased throughput under heavy network load.
A prototype implementation of LRP was constructed by modifying the TCP/UDP/IP network subsystem of the 4.4BSD-Lite distribution to optionally implement LRP as a new protocol family. The prototype was tested and evaluated on a ATM network of SparcStation 20s by downloading this code into the SunOS kernel as a loadable kernel module. Experiments on this testbed show that under high network load, the LRP system is dramatically more stable and yields higher throughput than the 4.4BSD network system, without any performance degradation under normal conditions. We plan to release our source code as soon as licensing issues have been resolved.
For more details about LRP refer to an extended version of our OSDI'96 paper in html or to the conference version in postscript or contact us at gaurav@cs.rice.edu or druschel@cs.rice.edu.