Abstract: Techniques and devices are provided for injecting transactions within computer systems having a plurality of multi-processor clusters. Each cluster includes a plurality of nodes, including processors, a service processor and an interconnection controller interconnected by point-to-point intra-cluster links. The processors and the interconnection controller in each cluster make transactions via an intra-cluster transaction protocol. Inter-cluster links are formed between interconnection controllers of different clusters. Each of the processors and the interconnection controller in a cluster has a test interface for communicating with the service processor. The service processor is configured to make an injected transaction according to the intra-cluster transaction protocol via one of the test interfaces.

Abstract: A computer system having a plurality of processing nodes interconnected by a first point-to-point architecture is described. Each processing node has a cache memory associated therewith. A probe filtering unit is operable to receive probes corresponding to memory lines from the processing nodes and to transmit the probes only to selected ones of the processing nodes with reference to probe filtering information. The probe filtering information is representative of states associated with selected ones of the cache memories.

Abstract: According to the present invention, methods and apparatus are provided for increasing the efficiency of data access in a multiple processor, multiple cluster system. Mechanisms for transmitting memory cancels to memory controllers in the various clusters of a multiple cluster system are provided. In one example, memory cancels are transmitted between clusters when it is determined that a memory line associated with a probe is dirty. The memory cancel directs the memory controller to no longer proceed with a data fetch from main memory. In another example, memory cancels are transmitted at a home cluster based on information in a coherence directory in order to more quickly end a data fetch.

Abstract: Improved techniques are provided for detecting and correcting errors and skew in inter-cluster communications within computer systems having a plurality of multi-processor clusters. The local nodes of each cluster include a plurality of processors and an interconnection controller. Intra-cluster links are formed between the local nodes, including the interconnection controller, within a cluster. Inter-cluster links are formed between interconnection controllers of different clusters. Intra-cluster packets may be serialized and encapsulated as inter-cluster packets for transmission on inter-cluster links, preferably with link-layer encapsulation. Each inter-cluster packet may include a sequence identifier and error information computed for that packet. Clock data may be embedded in symbols sent on each bit lane of the inter-cluster links. Copies of transmitted inter-cluster packets may be stored until an acknowledgement is received.

Abstract: A multi-processor computer system is described in which address mapping, routing, and transaction identification mechanisms are provided which enable the interconnection of a plurality of multi-processor clusters, wherein the number of processors interconnected exceeds limited address, node identification, and transaction tag spaces associated with each of the individual clusters.

Abstract: Improved techniques are provided for detecting and correcting errors and skew in inter-cluster communications within computer systems having a plurality of multi-processor clusters. The local nodes of each cluster include a plurality of processors and an interconnection controller. Intra-cluster links are formed between the local nodes, including the interconnection controller, within a cluster. Inter-cluster links are formed between interconnection controllers of different clusters. Intra-cluster packets may be serialized and encapsulated as inter-cluster packets for transmission on inter-cluster links, preferably with link-layer encapsulation. Each inter-cluster packet may include a sequence identifier and error information computed for that packet. Clock data may be embedded in symbols sent on each bit lane of the inter-cluster links. Copies of transmitted inter-cluster packets may be stored until an acknowledgement is received.

Abstract: Improved techniques are provided for detecting and correcting errors and skew in inter-cluster communications within computer systems having a plurality of multi-processor clusters. The local nodes of each cluster include a plurality of processors and an interconnection controller. Intra-cluster links are formed between the local nodes, including the interconnection controller, within a cluster. Inter-cluster links are formed between interconnection controllers of different clusters. Intra-cluster packets may be serialized and encapsulated as inter-cluster packets for transmission on inter-cluster links, preferably with link-layer encapsulation. Each inter-cluster packet may include a sequence identifier and error information computed for that packet. Clock data may be embedded in symbols sent on each bit lane of the inter-cluster links. Copies of transmitted inter-cluster packets may be stored until an acknowledgement is received.

Abstract: According to the present invention, methods and apparatus are provided for increasing the efficiency and effectiveness of communications between multiprocessor clusters. Mechanisms for improving the accuracy of information available to an interconnection controller are implemented in order to allow the interconnection controller to increase reliability and reduce latency in a multiple cluster system. Protocol extensions and link layer extensions are provided with packets to convey information between interconnection controllers of separate multiprocessor clusters.

Abstract: A computer system is described having a plurality of processing nodes interconnected by a first point-to-point architecture, and a system memory including a plurality of portions each of which is associated with one of the processing nodes. Each processing node includes a processor, and a memory controller for controlling access to the associated portion of the system memory, and may contain a host bridge for facilitating communication with a plurality of I/O devices. The first point-to-point architecture is operable to facilitate first transactions between the processors and the system memory. The computer system further includes at least one I/O controller and a second point-to-point architecture independent of the first point-to-point architecture and interconnecting the I/O controller and the host bridges. The at least one I/O controller is operable to facilitate second transactions between the I/O devices and the system memory via the second point-to-point architecture.

Abstract: A method includes detecting a first pending event related a first thread being processed within a multithreaded processor. Responsive to the detection of the first pending event, a second thread being processed within the multithreaded processor is monitored to detect an event handling point for the second thread. Responsive to the detection of the event handling point for the second thread, at least a first event handler is invoked to handle at least the first pending event.

Abstract: Cache coherence directory eviction mechanisms are described for use in computer systems having a plurality of multiprocessor clusters. Interaction among the clusters is facilitated by a cache coherence controller in each cluster. A cache coherence directory is associated with each cache coherence controller identifying memory lines associated with the local cluster which are cached in remote clusters. An eviction manager is operable to designate one of the entries in the cache coherence directory to be evicted and maintain the designated entry in the cache coherence directory at least until a serialization point allows an eviction transaction corresponding to the designated entry to proceed.

Abstract: Cache coherence directory eviction mechanisms are described for use in computer systems having a plurality of multiprocessor clusters. Interaction among the clusters is facilitated by a cache coherence controller in each cluster. A cache coherence directory is associated with each cache coherence controller identifying memory lines associated with the local cluster which are cached in remote clusters. The cache coherence controller is operable to initiate eviction of an entry in its directory corresponding to an unmodified copy of a memory line by sending a request to write to the memory line to a corresponding memory controller.

Abstract: Cache coherence directory eviction mechanisms are described for use in computer systems having a plurality of multiprocessor clusters. Interaction among the clusters is facilitated by a cache coherence controller in each cluster. A cache coherence directory is associated with each cache coherence controller identifying memory lines associated with the local cluster which are cached in remote clusters. The cache coherence controller is operable to initiate eviction of an entry in its directory corresponding to a modified copy of a memory line by sending a request to merge an empty data field with the modified copy of the memory line to a corresponding memory controller.

Abstract: A system includes a multithreaded processor, a memory to store the plurality of threads, and a bus to deliver the plurality of threads to the multithreaded processor. The multithreaded processor includes an event detector to detect a first event indication for a first thread. The event detector, responsive to the detection of the first event indication for the first thread, monitors a second thread being processed within the multithreaded processor to detect a clearing point for the second thread and, responsive to the detection of the clearing point for the second thread clears a functional unit within the multithreaded processor for at least the first thread.

Abstract: A method includes maintaining a state machine to provide a multi-bit output, each bit of the multi-bit output indicating a respective status for an associated thread of multiple threads being executed within a multithreaded processor. Status for a first thread is detected, responsive to which a functional unit within the multithreaded processor is configured in accordance with the multi-bit output of the state machine.

Abstract: A method and apparatus are provided for entering and exiting multiple threads within a multithreaded processor. A state machine is maintained to indicate a respective status of an associated thread of multiple threads being executed within a multithreaded processor. A change of status for a first thread within the multithreaded processor is detected and, responsive to the change of status for the first thread within the multithreaded processor, a partitioning scheme for the functional unit is altered to service a second thread, but not the first thread, within the multithreaded processor when the change of the status of the first thread comprises a transition from an active state to an inactive state.

Abstract: Improved techniques are provided for detecting and correcting errors and skew in inter-cluster communications within computer systems having a plurality of multi-processor clusters. The local nodes of each cluster include a plurality of processors and an interconnection controller. Intra-cluster links are formed between the local nodes, including the interconnection controller, within a cluster. Inter-cluster links are formed between interconnection controllers of different clusters. Intra-cluster packets may be serialized and encapsulated as inter-cluster packets for transmission on inter-cluster links, preferably with link-layer encapsulation. Each inter-cluster packet may include a sequence identifier and error information computed for that packet. Clock data may be embedded in symbols sent on each bit lane of the inter-cluster links. Copies of transmitted inter-cluster packets may be stored until an acknowledgement is received.

Abstract: Improved techniques are provided for detecting and correcting errors and skew in inter-cluster communications within computer systems having a plurality of multi-processor clusters. The local nodes of each cluster include a plurality of processors and an interconnection controller. Intra-cluster links are formed between the local nodes, including the interconnection controller, within a cluster. Inter-cluster links are formed between interconnection controllers of different clusters. Intra-cluster packets may be serialized and encapsulated as inter-cluster packets for transmission on inter-cluster links, preferably with link-layer encapsulation. Each inter-cluster packet may include a sequence identifier and error information computed for that packet. Clock data may be embedded in symbols sent on each bit lane of the inter-cluster links. Copies of transmitted inter-cluster packets may be stored until an acknowledgement is received.

Abstract: Improved techniques are provided for detecting and correcting errors and skew in inter-cluster communications within computer systems having a plurality of multi-processor clusters. The local nodes of each cluster include a plurality of processors and an interconnection controller. Intra-cluster links are formed between the local nodes, including the interconnection controller, within a cluster. Inter-cluster links are formed between interconnection controllers of different clusters. Intra-cluster packets may be serialized and encapsulated as inter-cluster packets for transmission on inter-cluster links, preferably with link-layer encapsulation. Each inter-cluster packet may include a sequence identifier and error information computed for that packet. Clock data may be embedded in symbols sent on each bit lane of the inter-cluster links. Copies of transmitted inter-cluster packets may be stored until an acknowledgement is received.

Abstract: Improved techniques are provided for detecting and correcting errors and skew in inter-cluster communications within computer systems having a plurality of multi-processor clusters. The local nodes of each cluster include a plurality of processors and an interconnection controller. Intra-cluster links are formed between the local nodes, including the interconnection controller, within a cluster. Inter-cluster links are formed between interconnection controllers of different clusters. Intra-cluster packets may be serialized and encapsulated as inter-cluster packets for transmission on inter-cluster links, preferably with link-layer encapsulation. Each inter-cluster packet may include a sequence identifier and error information computed for that packet. Clock data may be embedded in symbols sent on each bit lane of the inter-cluster links. Copies of transmitted inter-cluster packets may be stored until an acknowledgement is received.