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Abstra t Di erentiated servi e approa h has been proposed as a potential solution to provide Quality of Servi es (QoS) in the next generation Internet. The ultimate goal of end-to-end servi e di erentiation an be a hieved by omplementing the network-level QoS with the servi e differentiation at the Internet servers. In this paper, we have presented a detailed study of the performan e of servi e di erentiating web servers (SDIS). Various aspe ts, su h as admission ontrol, s heduling, and task assignment s hemes for SDIS have been evaluated through real workload tra es. The impa t of these aspe ts have been quanti ed in the simulation-based study. Under high system utilization, a servi e di erentiating server provides signi antly better servi es to high priority tasks ompared to a traditional Internet server. A ombination of sele tive early dis ard and priority-based task s heduling and assignment is required to provide eÆ ient servi e di erentiation at the servers. The results of these studies ould be used as a foundation for further studies on servi e di erentiating Internet servers.