Abstract: Systems, methodologies, media, and other embodiments associated with mitigating the effects of context switch cache and TLB misses are described. One exemplary system embodiment includes a processor configured to run a multiprocessing, virtual memory operating system. The processor may be operably connected to a memory and may include a cache and a translation lookaside buffer (TLB) configured to store TLB entries. The exemplary system may include a context control logic configured to selectively copy data from the TLB to the data store for a first process being swapped out of the processor and to selectively copy data from the data store to the TLB for a second process being swapped into to the processor.

Abstract: In a computer system including a plurality of resources, a device receives a request from a software program to access a specified one of the plurality of resources, determines whether the specified one of the plurality of resources is a protected resource. If the specified one of the plurality of resources is a protected resource, the device denies the request if the computer system is operating in a protected mode of operation, and processes the request based on access rights associated with the software program if the computer system is not operating in the protected mode of operation.

Abstract: Provided is a system to communicate data in a computing environment, comprising an interleaving mechanism operable to interleave data being communicated across the computing environment according to a selected interleaving protocol; and an interleaving instruction set operable on the interleaving mechanism providing operating instructions to the interleaving mechanism in accordance with the selected interleaving protocol wherein the data can be interleaved between one or more data channels of the computing environment and within one or more data channels of the computing environment.

Abstract: Provided is a system to communicate data in a computing environment, comprising an interleaving mechanism operable to interleave data being communicated across the computing environment according to a selected interleaving protocol; and an interleaving instruction set operable on the interleaving mechanism providing operating instructions to the interleaving mechanism in accordance with the selected interleaving protocol wherein the data can be interleaved between one or more data channels of the computing environment and within one or more data channels of the computing environment.

Abstract: A crossbar and method for providing connections between a plurality of ports and a plurality of system agents via a processing system, which includes a plurality of ports, each port being capable of being an input port customized for receiving data from a source agent and an output port customized for transferring data to a destination agent, and crossbar control data for specifying crossbar control information for transferring data from an input port to an output port having different port configurations.

Abstract: A system and method are disclosed which determine in parallel for multiple levels of a multi-level cache whether any one of such multiple levels is capable of satisfying a memory access request. Tags for multiple levels of a multi-level cache are accessed in parallel to determine whether the address for a memory access request is contained within any of the multiple levels. For instance, in a preferred embodiment, the tags for the first level of cache and the tags for the second level of cache are accessed in parallel. Also, additional levels of cache tags up to N levels may be accessed in parallel with the first-level cache tags. Thus, by the end of the access of the first-level cache tags it is known whether a memory access request can be satisfied by the first-level, second-level, or any additional N-levels of cache that are accessed in parallel.

Abstract: The present invention provides a software-assisted hardware TLB miss-handler which is designed to reduce the TLB miss penalty while being low cost to implement and requiring little chip area or complexity. When a TLB miss occurs, the HW TLB miss handler of the present invention computes a physical address of a page table entry located in a special hardware-visible table based on a missing virtual address. It accesses the page table entry and checks for a correct translation and status information. If correct, a physical page address and protection information of the page table entry are inserted into the TLB. The original virtual address is re-translated and normal program execution continues. If the correct translation and status are not found, the HW TLB miss-handler will not insert the entry and will trap to a more sophisticated SW TLB miss handler. A pointer to the page table entry is passed to the SW TLB miss handler so that the page table address need not be recomputed.

Abstract: The present invention is directed to a system and method for selecting instruction words from a memory system for simultaneous execution in an execution unit of a computer system. In one example, an instructor selector unit of the present invention employs an addressing unit to fetch instructions from an instruction cache. The instructor selector unit also employs a receiver unit for buffering and transferring multiple aligned as well as misaligned instructions. The instruction selector unit supplies these instructions to an instruction execution unit (having an integer unit and a floating point unit), which is capable of executing two bundled instructions simultaneously. The instruction selector unit can provide instructions to the instruction execution unit individually, or as a bundled pair.

Abstract: Pipeline structure that is arranged to allow 1.5 cycle access time for both data and instruction cache without imposing additional instruction step delays than that imposed by data and instruction cache that have 1 cycle access time. Half cycle pulses are produced to allow execution of various instructions in 0.5 cycles. A bypass signal is generated to allow data from a current load instruction to be available for a second subsequent instruction even though the access time for data cache is 1.5 cycles. Additionally, a branch address is available for a third subsequent instruction even though instruction cache access time is 1.5 cycles. The present invention shows the initiation of an instruction step for each cycle and 1.5 cycle access time for cache memory. The present invention can also be implemented by implementing an instruction every 2 cycles and providing 3 cycle access time for cache memory.

Abstract: The present invention provides a software-assisted hardware TLB miss-handler which is designed to reduce the TLB miss penalty while being low cost to implement and requiring little chip area or complexity. When a TLB miss occurs, the HW TLB miss handler of the present invention computes a physical address of a page table entry located in a special hardware-visible table based on a missing virtual address. It accesses the page table entry and checks for a correct translation and status information. If correct, a physical page address and protection information of the page table entry are inserted into the TLB. The original virtual address is re-translated and normal program execution continues. If the correct translation and status are not found, the HW TLB miss-handler will not insert the entry and will trap to a more sophisticated SW TLB miss handler. A pointer to the page table entry is passed to the SW TLB miss handler so that the page table address need not be recomputed.

Abstract: A system and method for scoreboarding individual cache line units in order to reduce the cache store-miss penalty is disclosed. Store operations to cache addresses which generate a store-miss are allowed to occur during the same time period that a missing line is being retrieved from memory. The cache memory is divided into a plurality of cache lines, each of the cache lines having a plurality of data units. A store-scoreboard, associated with a selected one of the cache lines, maintains a record of the contents of the plurality of data units within the selected cache line. Memory access performance is improved by allowing stores which miss the cache to complete in advance of the miss copy-in and by allowing multiple stores to the same cache line (being retrieved from memory) to occur without a penalty during the latency period of the store miss. Furthermore, a "safety net" is provided for hinted store instructions.

Abstract: Synchronization of an architectural model of a computer architecture and a behavioral model of an implementation of the architecture for functional verification of the implementation. A communication channel is established between the two models through which simulation control and state information can be communicated and both models are available for simulating. Synchronization points in the models' executions are identified, and a synchronizer is implemented which instructs each model to simulate to a synchronization point and report relevant state information. The synchronizer can also verify state information from the two models in real time, flag errors, or instruct the architectural model to modify its state either to match known errors in the behavioral model or to match correct behavior to an asynchronous event.

Abstract: A computer system having a central processor unit (CPU) with a reduced instruction set, a decoder and a data cache memory, for processing an instruction to retrieve data from a main memory to prevent a data cache miss. The system decodes an instruction requiring the CPU to load a value into a read only general purpose memory register, the instruction thereby indicating to the CPU to perform a prefetch operation and providing information corresponding to an address of the data to be fetched from the main memory. The system processes, substantially simultaneously, further instructions following the load register instruction and the prefetch operation by determining the address in main memory of the data to be prefetched using the information provided by the load instruction, fetching the data from the main memory, and storing the data in the data cache memory to permit accesses to the data and thereby reduce the penalty associated with a data cache miss.

Abstract: A system and method of producing predecode bits from instructions as instructions are copied from a memory system to a cache memory unit. A predecode unit, coupled between the memory unit and the cache memory unit, produces the predecode bits for utilization by a superscalar processor. The circuitry of the predecode unit is comprised of logic and latches. The predecode unit includes two main paths for transporting instruction information: a predecode path and an instruction path. The instruction path buffers instructions sent from memory to cache as information from these instructions are decoded in the predecode path. The predecode path includes a decoder and a bit information unit. The decoder identifies the instruction type by monitoring the op-code of instructions entering the predecode unit. The bit information unit is coupled to the decoder and receives signals indicating instruction type and passes these signals through logic gates to obtain whether instructions can be bundled.