Abstract: A memory system, apparatus and method for performing operations in a shared cache coupled to a first requester and a second requester. The method includes receiving at the shared cache a first request from the second requester; assigning the request to a state machine; transmitting a first pipe pass request from the state machine to an arbiter; providing a first instruction from the first pipe pass request to a cache pipeline, the first instruction causing a first pipe pass; and providing a second pipe pass request to the arbiter before the first pipe pass is completed. The first requester may be a lower level cache such as an L2 cache, or an I/O device and the second requester may be an upper level cache such as an L4 cache, and the first request may be a coherency request.

Abstract: A computer-program product that includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes receiving a plurality of stores in a store queue, via a processor, comparing a fetch request against the store queue to search for a target store having a same memory address as the fetch request, determining whether the target store is ahead of the fetch request in a same pipeline, and processing the fetch request when it is determined that the target store is ahead of the fetch request.

Abstract: A method of managing a temporary memory includes: receiving a request to transfer data from a source location to a destination location, the data transfer request associated with an operation to be performed, the operation selected from an input into an intermediate temporary memory and an output; checking a two-state indicator associated with the temporary memory, the two-state indicator having a first state indicating that an immediately preceding operation on the temporary memory was an input to the temporary memory and a second state indicating that the immediately preceding operation was an output from the temporary memory; and performing the operation responsive to one of: the operation being an input operation and the two-state indicator being in the second state, indicating that the immediately preceding operation was an output; and the operation being an output operation and the two-state indicator being in the first state, indicating that the immediately preceding operation was an input.

Abstract: A cache includes a cache pipeline, a request receiver configured to receive off chip coherency requests from an off chip cache and a plurality of state machines coupled to the request receiver. The cache also includes an arbiter coupled between the plurality of state machines and the cache pipe line and is configured to give priority to off chip coherency requests as well as a counter configured to count the number of coherency requests sent from the cache pipeline to a lower level cache. The cache pipeline is halted from sending coherency requests when the counter exceeds a predetermined limit.

Abstract: A computer-implemented method for managing data transfer in a multi-level memory hierarchy that includes receiving a fetch request for allocation of data in a higher level memory, determining whether a data bus between the higher level memory and a lower level memory is available, bypassing an intervening memory between the higher level memory and the lower level memory when it is determined that the data bus is available, and transferring the requested data directly from the higher level memory to the lower level memory.

Abstract: A computer-implemented method that includes receiving a plurality of stores in a store queue, via a processor, comparing a fetch request against the store queue to search for a target store having a same memory address as the fetch request, determining whether the target store is ahead of the fetch request in a same pipeline, and processing the fetch request when it is determined that the target store is ahead of the fetch request.

Abstract: A computer-implemented method for collecting diagnostic data within a multiprocessor system that includes capturing diagnostic data via a plurality of collection points disposed at a source location within the multiprocessor system, routing the captured diagnostic data to a data collection station at the source location, providing a plurality of buffers within the data collection station, and temporarily storing the captured diagnostic data on at least one of the plurality of buffers, and transferring the captured diagnostic data to a target storage location on a same chip as the source location or another storage location on a same node.

Abstract: A pipelined processing device includes: a processor configured to receive a request to perform an operation; a plurality of processing controllers configured to receive at least one instruction associated with the operation, each of the plurality of processing controllers including a memory to store at least one instruction therein; a pipeline processor configured to receive and process the at least one instruction, the pipeline processor including shared error detection logic configured to detect a parity error in the at least one instruction as the at least one instruction is processed in a pipeline and generate an error signal; and a pipeline bus connected to each of the plurality of processing controllers and configured to communicate the error signal from the error detection logic.

Abstract: A cache includes a cache pipeline, a request receiver configured to receive off chip coherency requests from an off chip cache and a plurality of state machines coupled to the request receiver. The cache also includes an arbiter coupled between the plurality of state machines and the cache pipe line and is configured to give priority to off chip coherency requests as well as a counter configured to count the number of coherency requests sent from the cache pipeline to a lower level cache. The cache pipeline is halted from sending coherency requests when the counter exceeds a predetermined limit.

Abstract: A mechanism for dynamically altering a request received at a hardware component is provided. The request is received at the hardware component, and the request includes a mode option. It is determined whether an action of the request requires an unavailable resource and it is determined whether the mode option is for the action requiring the unavailable resource. In response to the mode option being for the action requiring the unavailable resource, the action is automatically removed from the request. The request is passed for pipeline arbitration without the action requiring the unavailable resource.

Abstract: An apparatus for controlling access to a pipeline includes a plurality of command queues including a first subset of the plurality of command queues being assigned processes the commands of first command type, a second subset of the plurality of command queues being assigned to process commands of the second command type, and a third subset of the plurality of the command queues not being assigned to either the first subset or the second subset. The apparatus also includes an input controller configured to receive requests having the first command type and the second command type and assign requests having the first command type to command queues in the first subset until all command queues in the first subset are filled and then assign requests having the first command type to command queues in the third subset.

Abstract: Dynamic re-allocation of cache buffer slots includes moving data out of a reserved buffer slot upon detecting an error in the reserved buffer slot, creating a new buffer slot, and storing the data moved out of the reserved buffer slot in the new buffer slot.

Abstract: Dynamic allocation of cache buffer slots includes receiving a request to perform an operation that requires a storage buffer slot, the storage buffer slot residing in a level of storage. The dynamic allocation of cache buffer slots also includes determining availability of the storage buffer slot for the cache index as specified by the request. Upon determining the storage buffer slot is not available, the dynamic allocation of cache buffer slots includes evicting data stored in the storage buffer slot, and reserving the storage buffer slot for data associated with the request.

Abstract: A method of providing requests to a cache pipeline includes receiving a plurality of requests from one or more state machines at an arbiter, selecting one of the plurality of requests as a selected request, the selected request having been provided by a first state machine, determining that the selected request includes a mode that requires a first step and a second step, the first step including an access to a location in a cache, determining that the location in the cache is unavailable, and replacing the mode with a modified mode that only includes the second step.

Abstract: A pipelined processing device includes: a device controller configured to receive a request to perform an operation; a plurality of subcontrollers configured to receive at least one instruction associated with the operation, each of the plurality of subcontrollers including a counter configured to generate an active time value indicating at least a portion of a time taken to process the at least one instruction; a pipeline processor configured to receive and process the at least one instruction, the pipeline processor configured to receive the active time value; and a shared pipeline storage area configured to store the active time value for each of the plurality of subcontrollers.

Abstract: A computer-implemented method that includes receiving a plurality of stores in a store queue, via a processor, comparing a fetch request against the store queue to search for a target store having a same memory address as the fetch request, determining whether the target store is ahead of the fetch request in a same pipeline, and processing the fetch request when it is determined that the target store is ahead of the fetch request.

Abstract: A method of performing operations in a shared cache coupled to a first requestor and a second requestor includes receiving at the shared cache a first request from the second requester; assigning the request to a state machine; transmitting a first pipe pass request from the state machine to an arbiter; providing a first instruction from the first pipe pass request to a cache pipeline, the first instruction causing a first pipe pass; and providing a second pipe pass request to the arbiter before the first pipe pass is completed.

Abstract: An apparatus for controlling access to a resource includes a shared pipeline configured to communicate with the resource, a plurality of command queues configured to form instructions for the shared pipeline and an arbiter coupled between the shared pipeline and the plurality of command queues configured to grant access to the shared pipeline to a one of the plurality of command queues based on a first priority scheme in a first operating mode. The apparatus also includes interface logic coupled to the arbiter and configured to determine that contention for access to the resource exists among the plurality of command queues and to cause the arbiter to grant access to the shared pipeline based on a second priority scheme in second operating mode.

Abstract: A method that includes providing LRU selection logic which controllably pass requests for access to computer system resources to a shared resource via a first level and a second level, determining whether a request in a request group is active, presenting the request to LRU selection logic at the first level, when it is determined that the request is active, determining whether the request is a LRU request of the request group at the first level, forwarding the request to the second level when it is determined that the request is the LRU request of the request group, comparing the request to an LRU request from each of the request groups at the second level to determine whether the request is a LRU request of the plurality of request groups, and selecting the LRU request of the plurality of request groups to access the shared resource.

Abstract: A computer-implemented method for managing data transfer in a multi-level memory hierarchy that includes receiving a fetch request for allocation of data in a higher level memory, determining whether a data bus between the higher level memory and a lower level memory is available, bypassing an intervening memory between the higher level memory and the lower level memory when it is determined that the data bus is available, and transferring the requested data directly from the higher level memory to the lower level memory.