Patent ID: 8490107

Claim:
An integrated circuit comprising: a plurality of transaction sources configured to generate transaction requests; and request servicing circuitry configured to process said transaction requests using a set of processing resources; wherein said transaction requests each have an associated quality of service value within a range of quality of service values; said request servicing circuitry is configured to map, in accordance with a quality of service mapping configuration, quality of service values within different sub-ranges of said range of quality of service values to different priority levels within a hierarchy of priority levels extending from a lowest level to a highest level; and said request servicing circuitry is configured to provide a maximum number of said processing resources that can be concurrently allocated to service transaction requests within each level of said hierarchy, wherein said request servicing circuitry is configured to: to receive from a requesting transaction source from among said plurality of transaction sources an at least implicit request to allocate one of said set of processing resources for use by said requesting transaction source in processing a transaction associated with said transaction request; to determine if one of said set of processing resources is available for use by said requesting transaction source; if one of said set of processing resources is available for use by said requesting transaction source, then to allocate said one or said set of processing resources to said requesting transaction source for use in processing said transaction; and if none of said set of processing resources is available for use by said requesting transaction source, then to send a retry response to said requesting transaction source; said requesting transaction source is configured; to receive from said request servicing circuitry said retry response; and to respond to said retry response by waiting for a proceed response to be received from said request servicing circuitry before proceeding with said transaction associated with said transaction request; and said request servicing circuitry is configured: to track those of said plurality of transaction sources awaiting a proceed response; to allocate one of said set of processing resources to one of said transaction sources awaiting a proceed response; and to send a proceed response to said one of said transaction sources awaiting a proceed response.