摘要:
A technique to detect errors in a computer system. More particularly, at least one embodiment of the invention relates to using redundant virtual machines and comparison logic to detect errors occurring in input/output (I/O) operations in a computer system.
摘要:
A processor is disclosed having a fetch unit that initiating interrupt service routines in redundant, unsynchronized threads. A counter is provided to track the difference between leading and trailing threads in terms of the number of instructions committed by the instruction execution circuitry. When the processor receives an external interrupt signal, the instruction fetch unit stalls the leading thread until the counter indicates that the threads are synchronized, and then simultaneously initiates an interrupt service routine in each of the threads. In a second embodiment similar to the first, the instruction fetch unit does not stall the leading thread, but rather, immediately initiates the interrupt service routine in the leading thread, and copies the difference to an interrupt counter. When the counter reaches zero, the fetch unit initiates the interrupt service routine in the trailing thread.
摘要:
A simultaneous and redundantly threaded, pipelined processor executes the same set of instructions simultaneously as two separate threads to provide fault tolerance. One thread is processed ahead of the other thread so that the instructions in one thread are processed through the processor's pipeline ahead of the corresponding instructions from the other thread. The thread, whose instructions are processed earlier, places its committed stores in a store queue. Subsequently, the second thread places its committed stores in the store queue. A compare circuit periodically scans the store queue for matching store instructions. If otherwise matching store instructions differ in any way (address or data), then a fault has occurred in the processing and the compare circuits initiates fault recovery. If comparison of the two instructions reveals they are identical, the compare circuit allows only a single store instruction to pass to the data cache or the system main memory. In this way, transient faults are detected with a minimum amount of hardware overhead and independent of differences in the actual order of program execution or differences in branch speculation.
摘要:
A device interface for communicating between a processor system and a separate device employs cacheable control registers, both to indicate the receipt of a message and to receive messages to be transmitted. The data structure of the cacheable control registers may be that of a queue, minimizing the need for routine handshaking signals to clear the queue after each message. Communication of queue pointers is minimized by the use of a shadow pointer relied on as long as adequate queue space exists and queue entry valid flags which are interpreted with alternate sense for each cycling through the queue.
摘要:
A system and method for simulating new instructions without compiler support for the new instructions. A simulator detects a given region in code generated by a compiler. The given region may be a candidate for vectorization or may be a region already vectorized. In response to the detection, the simulator suspends execution of a time-based simulation. The simulator then serially executes the region for at least two iterations using a functional-based simulation and using instructions with operands which correspond to P or less lanes of single-instruction-multiple-data (SIMD) execution. The value P is a maximum number of lanes of SIMD exection supported both by the compiler. The simulator stores checkpoint state during the serial execution. In response to determining no inter-iteration memory dependencies exist, the simulator returns to the time-based simulation and resumes execution using N-wide vector instructions.
摘要:
A system and method for simulating new instructions without compiler support for the new instructions. A simulator detects a given region in code generated by a compiler. The given region may be a candidate for vectorization or may be a region already vectorized. In response to the detection, the simulator suspends execution of a time-based simulation. The simulator then serially executes the region for at least two iterations using a functional-based simulation and using instructions with operands which correspond to P or less lanes of single-instruction-multiple-data (SIMD) execution. The value P is a maximum number of lanes of SIMD exection supported both by the compiler. The simulator stores checkpoint state during the serial execution. In response to determining no inter-iteration memory dependencies exist, the simulator returns to the time-based simulation and resumes execution using N-wide vector instructions.
摘要:
A method includes bypassing a global coherence operation that maintains global memory coherence between a plurality of local memories associated with a plurality of corresponding processors. The bypassing is in response to an address of a memory request being associated with a local memory coherence domain. The method includes accessing a memory location associated with the local memory coherence domain according to the memory request in response to the address being associated with the local memory coherence domain.
摘要:
A system and method of providing directory cache coherence are disclosed. The system and method may include tracking the coherence state of at least one cache block contained within a region using a global directory, providing at least one region level sharing information about the least one cache block in the global directory, and providing at least one block level sharing information about the at least one cache block in the global directory. The tracking of the provided at least one region level sharing information and the provided at least one block level sharing information may organize the coherence state of the at least one cache block and the region.
摘要:
A data prefetcher includes a controller to control operation of the data prefetcher. The controller receives data associated with cache misses and data associated with events that do not rely on a prefetching function of the data prefetcher. The data prefetcher also includes a counter to maintain a count associated with the data prefetcher. The count is adjusted in a first direction in response to detection of a cache miss, and in a second direction in response to detection of an event that does not rely on the prefetching function. The controller disables the prefetching function when the count reaches a threshold value.
摘要:
A computer software product, methods and apparatus for target report generation are provided. In one embodiment, a trigger pattern is derived from at least one target pattern. Locations within a data set containing the trigger pattern are identified and a target report is generated. In another embodiment, a computing apparatus is provided that produces reports by deriving a trigger pattern, identifying locations within a dataset where the trigger patterns exist and generating a report. In a further embodiment, a computer software product is provided that configures an apparatus to generate a target report. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the subject matter of the disclosure contained herein. This Abstract is submitted with the explicit understanding that it will not be used to interpret or to limit the scope or the meaning of the claims.