Abstract: A system and structure for snooping cache memories of several snooping masters connected to a bus macro, wherein each non-originating snooping master has a cache memory, and wherein some, but less than all the cache memories, may have the data requested by an originating snooping master and wherein the needed data in an non-originating snooping master is marked as updated, and wherein a main memory having addresses for all data is connected to the bus macro. Only those non-originating snooping masters which may have the requested data are queried. All the non-originating snooping masters that have been queried reply. If a non-originating snooping master has the requested data marked as updated, that non-originating snooping master returns the updated data to the originating snooping master and possibly to the main memory. If none of the non-originating snooping masters has the requested data marked as updated, then the requested data is read from main memory.

Abstract: A method and structure for snooping cache memories of several snooping masters connected to a bus macro, wherein each non-originating snooping master has cache memory, and wherein some, but less than all the cache memories, may have the data requested by an originating snooping master and wherein the needed data in a non-originating snooping master is marked as updated, and wherein a main memory having addresses for all data is connected to the bus macro. Only those non-originating snooping masters which may have the requested data are queried. All the non-originating snooping masters that have been queried reply. If a non-originating snooping master has the requested data marked as updated, that non-originating snooping master returns the updated data to the originating snooping master and possibly to the main memory. If none of the non-originating snooping masters has the requested data marked as updated, then the requested data is read from main memory.

Abstract: A system and method for accessing a data cache having at least two ways for storing data at the same addresses. A first and second tag memory store first and second sets of tags identifying data stored in each of the ways. A translation device determines from a system address a tag identifying one of the ways. A first comparator compares tags in the address with a tag stored in the first tag memory. A second comparator compares a tag in the address with a tag stored in the second tag memory. A clock signal supplies clock signals to one or both of the ways in response to an access mode signal. The system can be operated so that either both ways of the associative data cache are clocked, in a high speed access mode, or it can apply clock signals to only one of the ways selected by an output from the first and second comparators in a power efficient mode of operation.

Abstract: A method and apparatus are provided for determining power events on an I/C chip for undissipated power to the chip, and wherein the chip includes a plurality of separately regulatable power consumers. A structure is provided for monitoring the occurrence of each power event to each power consumer, and determining the dissipation of power from each power event, and controlling power used by the chip responsive to the amount of undissipated power.

Abstract: In a system having a plurality of snooping masters coupled to a Bus Macro, a snoop filtering device and method are provided in at least one of the plurality of snooping masters. The snoop filtering device and method parse a snoop request issued by one of the plurality of snooping masters and return an Immediate Response if parsing indicates the requested data cannot possibly be contained in a responding snooping master. If parsing indicates otherwise the at least one plurality of snoop masters searches its resources and returns the requested data if marked updated.

Abstract: A method and system for reducing latency of a snoop tenure. A bus macro may receive a snoopable transfer request. The bus macro may determine which snoop controllers in a system will participate in the snoop transaction. The bus macro may then identify which participating snoop controllers are passive. Passive snoop controllers are snoop controllers associated with cache memories with cache lines only in the shared or invalid states of the MESI protocol. The snoop request may then be completed by the bus macro without waiting to receive responses from the passive participating snoop controllers. By not waiting for responses from passive snoop controllers, the bus macro may be able to complete the snoop request in a shorter amount of time thereby reducing the latency of the snoop tenure and improving performance of the system bus.

Abstract: A method and system for a pipelined bus interface macro for use in interconnecting devices within a computer system. The system and method utilizes a pipeline depth signal that indicates a number N of discrete transfer requests that may be sent by a sending device and received by a receiving device prior to acknowledgment of a transfer request by the receiving device. The pipeline depth signal may be dynamically modified, enabling a receiving device to decrement or increment the pipeline depth while one or more unacknowledged requests have been made. The dynamic modifications may occur responsive to many factors, such as an instantaneous reduction in system power consumption, a bus interface performance indicator, a receiving device performance indicator or a system performance indicator.

Abstract: A method and system for a pipelined bus interface macro for use in interconnecting devices within a computer system. The system and method utilizes a pipeline depth signal that indicates a number N of discrete transfer requests that may be sent by a sending device and received by a receiving device prior to acknowledgment of a transfer request by the receiving device. The pipeline depth signal may be dynamically modified, enabling a receiving device to decrement or increment the pipeline depth while one or more unacknowledged requests have been made. The dynamic modifications may occur responsive to many factors, such as an instantaneous reduction in system power consumption, a bus interface performance indicator, a receiving device performance indicator or a system performance indicator.

Abstract: A method and system for reducing latency of a snoop tenure A bus macro may receive a snoopable transfer request. The bus macro may determine which snoop controllers in a system will participate in the snoop transaction. The bus macro may then identify which participating snoop controllers are passive. Passive snoop controllers are snoop controllers associated with cache memories with cache lines only in the shared or invalid states of the MESI protocol. The snoop request may then be completed by the bus macro without waiting to receive responses from the passive participating snoop controllers. By not waiting for responses from passive snoop controllers, the bus macro may be able to complete the snoop request in a shorter amount of time thereby reducing the latency of the snoop tenure and improving performance of the system bus.

Abstract: A method and structure for snooping cache memories of several snooping masters connected to a bus macro, wherein each non-originating snooping master has cache memory, and wherein some, but less than all the cache memories, may have the data requested by an originating snooping master and wherein the needed data in a non-originating snooping master is marked as updated, and wherein a main memory having addresses for all data is connected to the bus macro.

Abstract: In a system having a plurality of snooping masters coupled to a Bus Macro, a snoop filtering device and method are provided in at least one of the plurality of snooping masters. The snoop filtering device and method parse a snoop request issued by one of the plurality of snooping masters and return an Immediate Response if parsing indicates the requested data cannot possibly be contained in a responding snooping master. If parsing indicates otherwise the at least one plurality of snoop masters searches its resources and returns the requested data if marked updated.