| Patent application number | Description | Published |
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| 20080209135 | DATA PROCESSING SYSTEM, METHOD AND INTERCONNECT FABRIC SUPPORTING DESTINATION DATA TAGGING - A data processing system includes a plurality of communication links and a plurality of processing units including a local master processing unit. The local master processing unit includes interconnect logic that couples the processing unit to one or more of the plurality of communication links and an originating master coupled to the interconnect logic. The originating master originates an operation by issuing a write-type request on at least one of the one or more communication links, receives from a snooper in the data processing system a destination tag identifying a route to the snooper, and, responsive to receipt of the combined response and the destination tag, initiates a data transfer including a data payload and a data tag identifying the route provided within the destination tag. | 08-28-2008 |
| 20080222648 | DATA PROCESSING SYSTEM AND METHOD OF DATA PROCESSING SUPPORTING TICKET-BASED OPERATION TRACKING - A data processing system includes a plurality of processing units coupled by a plurality of communication links for point-to-point communication such that at least some of the communication between multiple different ones of the processing units is transmitted via intermediate processing units among the plurality of processing units. The communication includes operations having a request and a combined response representing a system response to the request. At least each intermediate processing unit includes one or more masters that initiate first operations, a snooper that receives at least second operations initiated by at least one other of the plurality of processing units, a physical queue that stores master tags of first operations initiated by the one or more masters within that processing unit, and a ticketing mechanism that assigns to second operations observed at the intermediate processing unit a ticket number indicating an order of observation with respect to other second operations observed by the intermediate processing unit. The ticketing mechanism provides the ticket number assigned to an operation to the snooper for processing with a combined response of the operation. | 09-11-2008 |
| 20080250208 | System and Method for Improving the Page Crossing Performance of a Data Prefetcher - A system and method for improving the page crossing performance of a data prefetcher is presented. A prefetch engine tracks times at which a data stream terminates due to a page boundary. When a certain percentage of data streams terminate at page boundaries, the prefetch engine sets an aggressive profile flag. In turn, when the data prefetch engine receives a real address that corresponds to the beginning/end of a new page, and the aggressive profile flag is set, the prefetch engine uses an aggressive startup profile to generate and schedule prefetches on the assumption that the real address is highly likely to be the continuation of a long data stream. As a result, the system and method minimize latency when crossing real page boundaries when a program is predominately accessing long streams. | 10-09-2008 |
| 20080301377 | DATA PROCESSING SYSTEM, CACHE SYSTEM AND METHOD FOR UPDATING AN INVALID COHERENCY STATE IN RESPONSE TO SNOOPING AN OPERATION - A cache coherent data processing system includes at least first and second coherency domains. In a first cache memory within the first coherency domain of the data processing system, a coherency state field associated with a storage location and an address tag is set to a first data-invalid coherency state that indicates that the address tag is valid and that the storage location does not contain valid data. In response to snooping an exclusive access operation, the exclusive access request specifying a target address matching the address tag and indicating a relative domain location of a requestor that initiated the exclusive access operation, the first cache memory updates the coherency state field from the first data-invalid coherency state to a second data-invalid coherency state that indicates that the address tag is valid, that the storage location does not contain valid data, and whether a target memory block associated with the address tag is cached within the first coherency domain upon successful completion of the exclusive access operation based upon the relative location of the requestor. | 12-04-2008 |
| 20080307137 | DATA PROCESSING SYSTEM, METHOD AND INTERCONNECT FABRIC FOR SYNCHRONIZED COMMUNICATION IN A DATA PROCESSING SYSTEM - A data processing system includes a plurality of processing units, including at least a local master and a local hub, which are coupled for communication via a communication link. The local master includes a master capable of initiating an operation, a snooper capable of receiving an operation, and interconnect logic coupled to a communication link coupling the local master to the local hub. The interconnect logic includes request logic that synchronizes internal transmission of a request of the master to the snooper with transmission, via the communication link, of the request to the local hub. | 12-11-2008 |
| 20090006766 | DATA PROCESSING SYSTEM AND METHOD FOR PREDICTIVELY SELECTING A SCOPE OF BROADCAST OF AN OPERATION UTILIZING A HISTORY-BASED PREDICTION - According to a method of data processing, a predictor is maintained that indicates a historical scope of broadcast for one or more previous operations transmitted on an interconnect of a data processing system. A scope of broadcast of a subsequent operation is predictively selected by reference to the predictor. | 01-01-2009 |
| 20090265293 | Access speculation predictor implemented via idle command processing resources - An access speculation predictor is provided that may be implemented using idle command processing resources, such as registers of idle finite state machines (FSMs) in a memory controller. The access speculation predictor may predict whether to perform speculative retrieval of data for a data request from a main memory of the data processing system based on history information stored for a memory region targeted by the data request. In particular, a first address may be extracted from the data request and compared to memory regions associated with second addresses stored in address registers of a plurality of FSMs of the memory controller. A FSM whose memory region includes the first address may be selected. History information for the memory region may be obtained from the selected FSM. The history information may be used to control whether to speculatively retrieve the data for the data request from a main memory. | 10-22-2009 |
| 20090327612 | Access Speculation Predictor with Predictions Based on a Domain Indicator of a Cache Line - An access speculation predictor may predict whether to perform speculative retrieval of data for a data request from a main memory based on whether or not a domain indicator in the data request indicates that the cache line corresponding to the data has a special invalid state or not. In particular, a first address and a domain indicator are extracted from first data request. The first address is used to select a finite state machine (FSM) of a memory controller based on memory regions associated with the FSMs of the memory controller. Speculative retrieval of data for the first data request from main memory is controlled based on whether the domain indicator identifies the special invalid state or not and, if the domain indicator identifies that the cache line does not have the special invalid state, based on information stored in registers associated with the selected FSM. | 12-31-2009 |
| 20090327615 | Access Speculation Predictor with Predictions Based on a Scope Predictor - An access speculation predictor may predict whether to perform speculative retrieval of data for a data request from a main memory based on whether a scope predictor indicates whether a local or global request is predicted to be necessary to obtain the data for the data request. In particular, a first address and a scope predictor may be extracted from a first data request. A determination may be made as to whether a memory controller receiving the first data request is local to a source of the first data request or not. Speculative retrieval of the data for the first data request from a main memory may be controlled based on whether the memory controller is local to the source of the first data request and whether the scope predictor identifies whether a local or a global request is predicted to be necessary. | 12-31-2009 |
| 20090327619 | Access Speculation Predictor with Predictions Based on Memory Region Prior Requestor Tag Information - An access speculation predictor may predict whether to perform speculative retrieval of data for a data request from a main memory based on whether or not a current requestor tag matches a previous requestor tag. In particular, a first address and a first requester tag may be extracted from a first data request and a finite state machine (FSM) of a memory controller may be selected whose memory region includes the first address. A second requester tag, that identifies a previous requester that attempted to access the memory region association with the selected FSM, may be retrieved from a register associated with the selected FSM and compared to the first requester tag. Speculatively retrieving the data for the first data request from a main memory may be controlled based on results of the comparison of the first requester tag to the second requester tag. | 12-31-2009 |
| 20100100682 | Victim Cache Replacement - A data processing system includes a processor core having an associated upper level cache and a lower level victim cache. In response to a memory access request of the processor core that specifies a non-modifying access to a target coherency granule, a determination is made whether the memory access request hits or misses in a directory of the lower level victim cache. In response to determining that the memory access request hits in the lower level victim cache in a data-valid coherence state, the lower level victim cache provides the target coherency granule of the memory access request to the upper level cache. The lower level victim cache preserves the target coherency granule in the lower level victim cache in a shared coherence state if the memory access request is of a first type and invalidates the target coherency granule if the memory access request is of a second type. | 04-22-2010 |
| 20100100683 | Victim Cache Prefetching - A processing unit for a multiprocessor data processing system includes a processor core and a cache hierarchy coupled to the processor core to provide low latency data access. The cache hierarchy includes an upper level cache coupled to the processor core and a lower level victim cache coupled to the upper level cache. In response to a prefetch request of the processor core that misses in the upper level cache, the lower level victim cache determines whether the prefetch request misses in the directory of the lower level victim cache and, if so, allocates a state machine in the lower level victim cache that services the prefetch request by issuing the prefetch request to at least one other processing unit of the multiprocessor data processing system. | 04-22-2010 |
| 20100153650 | Victim Cache Line Selection - A cache memory includes a cache array including a plurality of congruence classes each containing a plurality of cache lines, where each cache line belongs to one of multiple classes which include at least a first class and a second class. The cache memory also includes a cache directory of the cache array that indicates class membership. The cache memory further includes a cache controller that selects a victim cache line for eviction from a congruence class. If the congruence class contains a cache line belonging to the second class, the cache controller preferentially selects as the victim cache line a cache line of the congruence class belonging to the second class based upon access order. If the congruence class contains no cache line belonging to the second class, the cache controller selects as the victim cache line a cache line belonging to the first class based upon access order. | 06-17-2010 |
| 20100262778 | Empirically Based Dynamic Control of Transmission of Victim Cache Lateral Castouts - In response to a data request, a victim cache line is selected for castout from a lower level cache, and a target lower level cache of one of the plurality of processing units is selected. A determination is made whether the selected target lower level cache has provided more than a threshold number of retry responses to lateral castout (LCO) commands of the first lower level cache, and if so, a different target lower level cache is selected. The first processing unit thereafter issues a LCO command on the interconnect fabric. The LCO command identifies the victim cache line to be castout and indicates that the target lower level cache is an intended destination of the victim cache line. In response to a successful coherence response to the LCO command, the victim cache line is removed from the first lower level cache and held in the second lower level cache. | 10-14-2010 |
| 20100262783 | Mode-Based Castout Destination Selection - In response to a data request of a first of a plurality of processing units, the first processing unit selects a victim cache line to be castout from the lower level cache of the first processing unit and determines whether a mode is set. If not, the first processing unit issues on the interconnect fabric an LCO command identifying the victim cache line and indicating that a lower level cache is the intended destination. If the mode is set, the first processing unit issues a castout command with an alternative intended destination. In response to a coherence response to the LCO command indicating success of the LCO command, the first processing unit removes the victim cache line from its lower level cache, and the victim cache line is held elsewhere in the data processing system. The mode can be set to inhibit castouts to system memory, for example, for testing. | 10-14-2010 |
| 20100262784 | Empirically Based Dynamic Control of Acceptance of Victim Cache Lateral Castouts - A second lower level cache receives an LCO command issued by a first lower level cache on an interconnect fabric. The LCO command indicates an address of a victim cache line to be castout from the first lower level cache and indicates that the second lower level cache is an intended destination of the victim cache line. The second lower level cache determines whether to accept the victim cache line from the first lower level cache based at least in part on the address of the victim cache line indicated by the LCO command. In response to determining not to accept the victim cache line, the second lower level cache provides a coherence response to the LCO command refusing the identified victim cache line. In response to determining to accept the victim cache line, the second lower level cache updates an entry corresponding to the identified victim cache line. | 10-14-2010 |
| 20100268882 | LOAD REQUEST SCHEDULING IN A CACHE HIERARCHY - A system and method for tracking core load requests and providing arbitration and ordering of requests. When a core interface unit (CIU) receives a load operation from the processor core, a new entry in allocated in a queue of the CIU. In response to allocating the new entry in the queue, the CIU detects contention between the load request and another memory access request. In response to detecting contention, the load request may be suspended until the contention is resolved. Received load requests may be stored in the queue and tracked using a least recently used (LRU) mechanism. The load request may then be processed when the load request resides in a least recently used entry in the load request queue. CIU may also suspend issuing an instruction unless a read claim (RC) machine is available. In another embodiment, CIU may issue stored load requests in a specific priority order. | 10-21-2010 |
| 20110047352 | MEMORY COHERENCE DIRECTORY SUPPORTING REMOTELY SOURCED REQUESTS OF NODAL SCOPE - A data processing system includes at least a first through third processing nodes coupled by an interconnect fabric. The first processing node includes a master, a plurality of snoopers capable of participating in interconnect operations, and a node interface that receives a request of the master and transmits the request of the master to the second processing unit with a nodal scope of transmission limited to the second processing node. The second processing node includes a node interface having a directory. The node interface of the second processing node permits the request to proceed with the nodal scope of transmission if the directory does not indicate that a target memory block of the request is cached other than in the second processing node and prevents the request from succeeding if the directory indicates that the target memory block of the request is cached other than in the second processing node. | 02-24-2011 |
| 20110161589 | SELECTIVE CACHE-TO-CACHE LATERAL CASTOUTS - A data processing system includes first and second processing units and a system memory. The first processing unit has first upper and first lower level caches, and the second processing unit has second upper and lower level caches. In response to a data request, a victim cache line to be castout from the first lower level cache is selected, and the first lower level cache selects between performing a lateral castout (LCO) of the victim cache line to the second lower level cache and a castout of the victim cache line to the system memory based upon a confidence indicator associated with the victim cache line. In response to selecting an LCO, the first processing unit issues an LCO command on the interconnect fabric and removes the victim cache line from the first lower level cache, and the second lower level cache holds the victim cache line. | 06-30-2011 |
