Abstract: A system and method for efficiently arbitrating traffic on a bus. A computing system includes a fabric for routing traffic among one or more agents and one or more endpoints. The fabric includes multiple arbiters in an arbitration hierarchy. Arbiters store traffic in buffers with each buffer associated with a particular traffic type and a source of the traffic. Arbiters maintain a respective urgency counter for keeping track of a period of time traffic of a particular type is blocked by upstream arbiters. When the block is removed, the traffic of the particular type has priority for selection based on the urgency counter. When arbiters receive feedback from downstream arbiters or sources, the arbiters adjust selection priority accordingly. For example, changes in bandwidth requirement, low latency tolerance and active status cause adjustments in selection priority of stored requests.

Abstract: A system and method for efficiently arbitrating traffic on a bus. A computing system includes a fabric for routing traffic among one or more agents and one or more endpoints. The fabric includes multiple arbiters in an arbitration hierarchy. Arbiters store traffic in buffers with each buffer associated with a particular traffic type and a source of the traffic. Arbiters maintain a respective urgency counter for keeping track of a period of time traffic of a particular type is blocked by upstream arbiters. When the block is removed, the traffic of the particular type has priority for selection based on the urgency counter. When arbiters receive feedback from downstream arbiters or sources, the arbiters adjust selection priority accordingly. For example, changes in bandwidth requirement, low latency tolerance and active status cause adjustments in selection priority of stored requests.

Abstract: A system and method for efficiently arbitrating traffic on a bus. A computing system includes a fabric for routing traffic among one or more agents and one or more endpoints. The fabric includes multiple arbiters in an arbitration hierarchy. Arbiters store traffic in buffers with each buffer associated with a particular traffic type and a source of the traffic. Arbiters maintain a respective urgency counter for keeping track of a period of time traffic of a particular type is blocked by upstream arbiters. When the block is removed, the traffic of the particular type has priority for selection based on the urgency counter. When arbiters receive feedback from downstream arbiters or sources, the arbiters adjust selection priority accordingly. For example, changes in bandwidth requirement, low latency tolerance and active status cause adjustments in selection priority of stored requests.

Abstract: A system and method for efficiently allocating data storage to agents. A computing system includes an interconnect with intermediate buffers for storing transactions and corresponding payload data during transport between sources and destinations. A data storage limit is set on an amount of data storage corresponding to outstanding transactions for each of the multiple sources based on the initial buffer assignments. A number of outstanding transactions for each of the multiple sources is limited based on a corresponding data storage limit. If the rate of allocation of a given buffer assigned to a first source exceeds a threshold, then a second source is selected with available space exceeding a threshold in an assigned buffer. If it is determined the second source is not assigned to a buffer with a rate of allocation exceeding a threshold, then buffer storage is reassigned from the second source to the first source.

Abstract: A system and method for efficiently disconnecting links in a communication fabric. A computing system includes a fabric for routing traffic among one or more agents and a memory controller for system memory. The fabric includes multiple hierarchical clusters with a split topology where the data links are physically separated from the control links. When the controller in an intermediate cluster or agent determines local resources are idle, the controller sends separate requests for link disconnect on each of the upstream control and data links. When a single acknowledgment of link disconnect is received, the controller does not proceed with any link disconnect. Rather, the controller waits until an acknowledgment of link disconnect is received for each of the upstream control and data links. If local resources remain idle, the controller sends confirmation upstream and performs a link disconnect for each of the upstream control and data links.

Abstract: A system and method for efficiently scheduling requests. In various embodiments, a processor sends commands such as read requests and write requests to an arbiter. The arbiter reduces latencies between commands being sent to a communication fabric and corresponding data being sent to the fabric. When the arbiter selects a given request, the arbiter identifies a first subset of stored requests affected by the given request being selected. The arbiter adjusts one or more attributes of the first subset of requests based on the selection of the given request. In one example, the arbiter replaces a weight attribute with a value, such as a zero value, indicating the first subset of requests should not be selected. Therefore, during the next selection by the arbiter, only the requests in a second subset different from the first subset are candidates for selection.

Abstract: A system and method for efficiently arbitrating traffic on a bus. A computing system includes a fabric for routing traffic among one or more agents and one or more endpoints. The fabric includes multiple arbiters in an arbitration hierarchy. Arbiters store traffic in buffers with each buffer associated with a particular traffic type and a source of the traffic. Arbiters maintain a respective urgency counter for keeping track of a period of time traffic of a particular type is blocked by upstream arbiters. When the block is removed, the traffic of the particular type has priority for selection based on the urgency counter. When arbiters receive feedback from downstream arbiters or sources, the arbiters adjust selection priority accordingly. For example, changes in bandwidth requirement, low latency tolerance and active status cause adjustments in selection priority of stored requests.

Abstract: A system and method for efficiently allocating data storage to agents. A computing system includes an interconnect with intermediate buffers for storing transactions and corresponding payload data during transport between sources and destinations. A data storage limit is set on an amount of data storage corresponding to outstanding transactions for each of the multiple sources based on the initial buffer assignments. A number of outstanding transactions for each of the multiple sources is limited based on a corresponding data storage limit. If the rate of allocation of a given buffer assigned to a first source exceeds a threshold, then a second source is selected with available space exceeding a threshold in an assigned buffer. If it is determined the second source is not assigned to a buffer with a rate of allocation exceeding a threshold, then buffer storage is reassigned from the second source to the first source.

Abstract: A system and method for efficiently disconnecting links in a communication fabric. A computing system includes a fabric for routing traffic among one or more agents and a memory controller for system memory. The fabric includes multiple hierarchical clusters with a split topology where the data links are physically separated from the control links. When the controller in an intermediate cluster or agent determines local resources are idle, the controller sends separate requests for link disconnect on each of the upstream control and data links. When a single acknowledgment of link disconnect is received, the controller does not proceed with any link disconnect. Rather, the controller waits until an acknowledgment of link disconnect is received for each of the upstream control and data links. If local resources remain idle, the controller sends confirmation upstream and performs a link disconnect for each of the upstream control and data links.

Abstract: A system and method for efficiently scheduling requests. In various embodiments, a processor sends commands such as read requests and write requests to an arbiter. The arbiter reduces latencies between commands being sent to a communication fabric and corresponding data being sent to the fabric. When the arbiter selects a given request, the arbiter identifies a first subset of stored requests affected by the given request being selected. The arbiter adjusts one or more attributes of the first subset of requests based on the selection of the given request. In one example, the arbiter replaces a weight attribute with a value, such as a zero value, indicating the first subset of requests should not be selected. Therefore, during the next selection by the arbiter, only the requests in a second subset different from the first subset are candidates for selection.

Abstract: A system and method for efficiently routing data in a communication fabric. A computing system includes a fabric for routing data among one or more agents and a memory controller for system memory. The fabric includes multiple hierarchical clusters with a split topology where the data links are physically separated from the control links. A given cluster receives a write command and associated write data, and stores them in respective buffers. The given cluster marks the write command as a candidate to be issued to the memory controller when it is determined the write data will arrive ahead of the write command at the memory controller after being issued. The given cluster prevents the write command from becoming a candidate to be issued when it is determined the write data may not arrive ahead of the write command at the memory controller.

Abstract: A system and method for efficiently bridging two communication protocols. In various embodiments, a computing system includes an interconnect for routing traffic among agents and endpoints. The agents use a first communication protocol and the endpoints use a second communication protocol that differs from the first protocol with regard to at least the ordering that is enforced between transactions. A bridge selects transactions of a first type and a second type used in the first protocol for processing based on the first protocol ordering while using acknowledgments used by the second protocol.