Having sufficient memory and scheduler resources available is of paramount importance in having a system that runs well. Although SQL Server and the SQLOS have many built-in algorithms to distribute these resources equitably, you often understand your resource needs better than the SQL Server Database Engine does.
SQL Server 2008 Enterprise Edition provides you with an interface for assigning scheduler and memory resources to groups of processes based on your determination of their needs. This interface is called the Resource Governor, which has the following goals:
Allow monitoring of resource consumption per workload, where a workload can be defined as a group of requests.
Enable workloads ...