  E-commerce Web-servers often face overload conditions during which
revenue-generating requests may be dropped or abandoned due to an increase in
the browsing requests. In this paper we present a simple, yet effective,
mechanism for overload control of E-commerce Web-servers. We develop an
E-commerce workload model that separates the browsing requests from
revenue-generating transaction requests. During overload, we apply LIFO
discipline in the browsing queues and use a dynamic priority model to service
them. The transaction queues are given absolute priority over the browsing
queues. This is called the LIFO-Pri scheduling discipline. Experimental results
show that LIFO-Pri dramatically improves the overall Web-server throughput
while also increasing the completion rate of revenue-generating requests. The
Web-server was able to operate at nearly 60% of its maximum capacity even when
offered load was 1.5 times its capacity. Further, when compared to a single
queue FIFO system, there was a seven-fold increase in the number of completed
revenue-generating requests during overload.
