Abstract: A computer system including a multi buffer data cache and method of caching data based on predicted temporal and spatial localities. A processor operates on operands under instruction control, the operands being stored in a main memory. The processor is coupled to the main memory via a data cache for prefetch and storage of operands referenced by the instructions. The data cache comprises an S-buffer for storing operands with strong temporal locality, and a P-buffer for storing operands with strong spatial locality. A control unit connected to the processor, the buffers and the main memory, determines what type of locality is involved in the operand referenced, based on whether the instruction accesses the main memory in a direct or indirect addressing mode as determined by a decoder unit of the processor, and governs operation of the buffer associated with the type of locality determined.

Abstract: A data prefetching arrangement for use between a computer processor and a main memory. The addresses of data to be prefetched are calculated by decoding instructions which have been prefetched by decoding prefetched instructions, the instructions having been in accordance with an intelligent prefetching scheme. The processor registers have two sections for respective access by the processor and a prefetch controller. The instruction registers may also contain an additional counter field which indicates the number of instruction cycles which must be executed before the register may be reliably utilized for prefetching data.

Abstract: A method for obtaining parallel instruction execution (PIE) for frequently used programming operations, such as database record compression or expansion, cryptographic encoding/decoding, page moving, etc., for which a hardware-assist may be provided. These functions can be performed in parallel with CPU processing by a PIE processing facility (PIE-PF). The method is hardware/microcode based and uses software control in supervisory mode. The preferred embodiment is controlled by privileged subsystem software under an operating system, and does not use I/O channel oriented off-load processing. When the CPU is interrupted during an incomplete parallel operation by the PIE-PF, it is checkpointed in main storage in a manner accessible to the subsystem. The subsystem (after completing a current CPU operation, such as a database record predicate evaluation, can check for the completion of the PIE-PF operation by examining an indicator in a control block in shared storage.

Abstract: A system for increasing the speed and efficiency of instruction execution by a computer processing system. An instruction cache is provided to receive a minor number of stored instructions for execution by the computer processing system. The instructions are prefetched and returned in cache based upon an analysis of instructions which are in the cache pending execution. Target instructions of branch instructions may be prefetched as a result of the analysis of a branch instruction pending in the cache. Other instructions may be retained in cache when they are tagged as being likely to be reused.

Abstract: A cache memory for use between a processing unit and a main memory includes a prefetch buffer, a use buffer, and a head buffer. The prefetched buffer is a FIFO or LRU register which prefetches instructions from contiguous memory locations after the address specified by the program counter. The head buffer is a FIFO or LRU register which is utilized to store instructions from the tops of the program blocks which are accessed from main memory following recent cache misses. The use buffer is a relatively large, inexpensive buffer, preferably a directly mapped buffer, which stores recent hits from the prefetched buffer as well as selected instructions from main memory following cache misses.

Abstract: Method for compiling program instructions to reduce instruction cache misses and instruction cache pollution. The program is analyzed for instructions which result in a non-sequential transfer of control in the program. The presence of branch instructions and program loops are identified and analyzed. The instructions are placed in lines, and the lines are placed in a sequence to minimize potential misses.