Abstract: A method and system are disclosed for managing saved process states in a memory of a data processing system that has multiple partitions executing independent operating systems. A hypervisor manager affords access to any processor in the data processing system for the purpose of storing process states for that processor to the memory, independent of the operating system running on the processor.

Abstract: A method and system are disclosed for managing a hard architected state of a processor that is critical for executing a process in the processor. A shadow copy of the hard architected state is stored from the processor to memory when an interrupt is received by the processor. The shadow copy of the hard architected permits rapid saving of the hard architected state for the interrupted process, so that the architected state of a next process can be immediately stored in the processor.

Abstract: A method and system are disclosed for predicting, based on historical information, a second level interrupt handler (SLIH) to service an interrupt. The predicted SLIH is speculatively executed concurrently with a first level interrupt handler (FLIH), which determines the correct SLIH for the interrupt. If the predicted SLIH has been correctly predicted, execution of the SLIH called by the FLIH is discontinued, and the predicted SLIH completes execution. If the predicted SLIH is mispredicted, then the execution of the predicted SLIH is discontinued, and the SLIH called by the FLIH continues to completion.

Abstract: A method and system are disclosed for running a manufacturing-level test program on an installed processor by interrupting processor execution of a non-test process. Periodic execution of the manufacturing-level test program allows the processor to continually self-test during normal function operation, in order to facilitate proper maintenance and function of the processor and a data processing system of which the processor is a part.

Abstract: A method, system and apparatus for instruction tracing with out of order speculative processors. With the present invention, information corresponding to the state of an instruction cache and a data cache is stored in a trace storage device along with information corresponding to instructions fetched by the processor. When a cache load is necessary, updated cache information is stored in the trace storage device. Thereby, the state of the cache at all times during fetching of instructions may be known from the information stored in the trace storage device. Additionally, the particular instructions fetched is known from the fetched instructions information stored in the trace storage device. Hence the instruction stream may be reconstructed from the information stored in the trace storage device.

Abstract: An apparatus for allocating data usage in an embedded dynamic random access memory (DRAM) device is disclosed. The apparatus for allocating data usages within an embedded dynamic random access memory (DRAM) device comprises a control analysis circuit, a data/command flow circuit, and a partition management control. The control analysis circuit generates an allocation signal in response to processing performances of a processor. Coupled to an embedded DRAM device, the data/command flow circuit controls data flow from the processor to the embedded DRAM device. The partition management control, coupled to the control analysis circuit, partitions the embedded DRAM device into a first partition and a second partition. The data stored in the first partition are different from the data stored in the second partition according to their respective usage. The allocation percentages of the first and second partitions are dynamically allocated by the allocation signal from the control analysis circuit.

Abstract: A method of prefetching addresses includes the step of accessing a stored instruction using a current address. During the access using the current address, a target address is accessed in a branch target address cache. A stored instruction associated with the target address accessed from the branch target address cache is prefetched and the branch target address is indexed with selected bits from the address accessed from the branch target address cache.

Abstract: A multiprocessor data processing system requires careful management to maintain cache coherency. Conventional systems using a MESI approach sacrifice some performance with inefficient lock-acquisition and lock-retention techniques. The disclosed system provides additional cache states, indicator bits, and lock-acquisition routines to improve cache performance. The additional cache states allow cache state transition sequences to be optimized by replacing frequently-occurring and inefficient MESI code sequences with improved sequences using modified cache states.

Abstract: A multiprocessor data processing system requires careful management to maintain cache coherency. In conventional systems using a MESI approach, two or more processors will often compete for ownership of a common cache line. As a result, ownership of the cache line will frequently “bounce” between multiple processors, which causes a significant reduction in cache efficiency. The preferred embodiment provides a modified MESI state which holds the status of the cache line static for a fixed period of time, which eliminates the bounce effect from contention between multiple processors.

Abstract: A multiprocessor data processing system requires careful management to maintain cache coherency. Conventional systems using a MESI approach sacrifice some performance with inefficient lock-acquisition and lock-retention techniques. The disclosed system provides additional cache states, indicator bits, and lock-acquisition routines to improve cache performance. The additional cache states allow cache state transition sequences to be optimized. In particular, the claimed system and method provides that a given processor, after acquiring a lock or reservation to a given cache line, will keep the lock, to make successive modifications to the cache line, instead of releasing it to other processors after making only one modification. By doing so, the overhead typically required to acquire a lock before making any cache line modification is eliminated for successive modifications.

Abstract: A multiprocessor data processing system requires careful management to maintain cache coherency. Conventional systems using a MESI approach sacrifice some performance with inefficient lock-acquisition and lock-retention techniques. The disclosed system provides additional cache states, indicator bits, and lock-acquisition routines to improve cache performance. In particular, as multiple processors compete for the same cache line, a significant amount of processor time is lost determining if another processor's cache line lock has been released and attempting to reserve that cache line while it is still owned by the other processor. The preferred embodiment provides an indicator bit with the cache store command which specifically indicates whether the store also acts as a lock-release.

Abstract: An apparatus for accessing a banked embedded dynamic random access memory device is disclosed. The apparatus for accessing a banked embedded dynamic random access memory (DRAM) device comprises a general functional control logic and a bank RAS controller. The general functional control logic is coupled to each bank of the banked embedded DRAM device. Coupled to the general functional control logic, the bank RAS controller includes a rotating shift register having multiple bits. Each bit within the rotating shift register corresponds to each bank of the banked embedded DRAM device. As such, a first value within a bit of the rotating shift register allows accesses to an associated bank of the banked embedded DRAM device, and a second value within a bit of the rotating shift register denies accesses to an associated bank of the banked embedded DRAM device.

Abstract: An information handling system includes a producer that outputs packets, a buffer that receives packets from the producer, buffers the packets, and eventually outputs the packets, and a control unit that controls the flow of packets from the producer to the buffer. The control unit receives as inputs a producer output indication indicating that the producer has output a packet to the buffer and a buffer output indication indicating that the buffer has output a packet. Based upon a capacity of the buffer, a number of the producer output indications, a number of buffer output indications, and a number of grant messages output to the producer within a feedback latency of the control unit, the control unit whether the producer can output a packet without packet loss. In response to a determination that the producer can output a packet without packet loss, the control unit outputs a grant message to the producer indicating that the producer is permitted to output a packet.

Abstract: An information handling system includes a plurality of producers that output packets of information, at least one consumer of the packets, and an information pipeline coupling the consumer and at least a particular producer among the plurality of producers. The information pipeline includes a shared resource having a bandwidth shared by multiple of the plurality of producers. The information handling system further includes a control unit that regulates packet output of the particular producer and that receives as inputs a producer output indication indicating that the particular producer output a packet and a shared resource input indication indicating that a packet output by the particular producer has been accepted by the shared resource for transmission to the consumer.

Abstract: An information handling system includes a producer that outputs packets of information, a plurality of buffers that can each receive packets from the producer and output the packets, and a control unit. The control unit receives at least one producer output indication indicating whether the producer output a packet to one of the plurality of buffers and a plurality of buffer output indications that each indicate whether a respective one of the plurality of buffers has output a packet. Based upon capacities of the plurality of buffers, the producer output indications, the buffer output indications and a number of grant messages output to the producer within a feedback latency of the control unit, the control unit whether the producer can output a packet without packet loss. If so, the control unit provides a grant message to the producer indicating that the producer is permitted to output a packet.

Abstract: An information handling system includes a plurality of sequentially connected units including a first unit, a second unit and a third unit. Packets of information flow from the first unit directly to the second unit and then to the third unit, and each of the plurality of units provides a respective dynamic output indication indicating if that unit output a packet. The information handling system further includes a control unit that determines, utilizing all of the plurality of dynamic output indications, packet buffering capacities of the plurality of units, and guaranteed packet flows between adjacent ones of the plurality of units, if the first unit can output a packet directly to the second unit without packet loss. In response to this determination, the control unit outputs a control signal to the first unit.

Abstract: An apparatus for providing concurrent communications between multiple memory devices and a processor is disclosed. Each of the memory device includes a driver, a phase/cycle adjust sensing circuit, and a bus alignment communication logic. Each phase/cycle adjust sensing circuit detects an occurrence of a cycle adjustment from a corresponding driver within a memory device. If an occurrence of a cycle adjustment has been detected, the bus alignment communication logic communicates the occurrence of a cycle adjustment to the processor. The bus alignment communication logic also communicates the occurrence of a cycle adjustment to the bus alignment communication logic in the other memory devices. There are multiple receivers within the processor, and each of the receivers is designed to receive data from a respective driver in a memory device. Each of the receivers includes a cycle delay block.

Abstract: A multiprocessor data processing system requires careful management to maintain cache coherency. Conventional systems using a MESI approach sacrifice some performance with inefficient lock-acquisition and lock-retention techniques. The disclosed system provides additional cache states, indicator bits, and lock-acquisition routines to improve cache performance. In particular, as multiple processors compete for the same cache line, a significant amount of processor time is lost determining if another processor's cache line lock has been released and attempting to reserve that cache line while it is still owned by the other processor. The preferred embodiment provides an additional cache state which specifically indicates that a processor has released its lock on a cache line after it has performed any necessary modifications.

Abstract: An apparatus for providing concurrent communications between multiple memory devices and a processor is disclosed. Each of the memory device includes a driver, a phase/cycle adjust sensing circuit, and a bus alignment communication logic. Each phase/cycle adjust sensing circuit detects an occurrence of a cycle adjustment from a corresponding driver within a memory device. If an occurrence of a cycle adjustment has been detected, the bus alignment communication logic communicates the occurrence of a cycle adjustment to the processor. The bus alignment communication logic also communicates the occurrence of a cycle adjustment to the bus alignment communication logic in the other memory devices. There are multiple receivers within the processor, and each of the receivers is designed to receive data from a respective driver in a memory device. Each of the receivers includes a cycle delay block.

Abstract: An apparatus for accessing a banked embedded dynamic random access memory device is disclosed. The apparatus for accessing a banked embedded dynamic random access memory (DRAM) device comprises a general functional control logic and a bank RAS controller. The general functional control logic is coupled to each bank of the banked embedded DRAM device. Coupled to the general functional control logic, the bank RAS controller includes a rotating shift register having multiple bits. Each bit within the rotating shift register corresponds to each bank of the banked embedded DRAM device. As such, a first value within a bit of the rotating shift register allows accesses to an associated bank of the banked embedded DRAM device, and a second value within a bit of the rotating shift register denies accesses to an associated bank of the banked embedded DRAM device.