With increases in the performance of computers, it has become possible to provide a large number of services on a single computer. However, since the required execution performance can vary from service to service, it is necessary to guarantee execution performance for each service individually. In addition, it is common for a single service to be composed of multiple processes. Consequently, the ability to regulate execution performance for units consisting of multiple processes is desirable. Therefore, in this paper we propose a mechanism for regulating the execution performance of process groups using execution resources that encapsulate the assignable processor units designed for the Tender operating system. Specifically, executions are managed in a tree-structure and we then regulate execution performance by associating processes with these executions. In addition, we show via an implementation and evaluations that the proposed method is able to regulate the execution performance of process groups well and present an evaluation that makes use of a Web server. © 2007 Wiley Periodicals, Inc.