International Business Machines Corporation

Michael James Mack

Scott Barnett Swaney

Dung Q Nguyen

Hung Qui Le

Jose Angel Paredes

Kenneth Lundy Ward

Susan Elizabeth Eisen

Guy L Guthrie

Timothy John Slegel

Chung-Lung K Shum

Eric M Schwarz

Fadi Y Busaba

Jeffrey A Stuecheli

Brian William Thompto

Bartholomew Blaner

Bryan J Lloyd

David Allen Hrusecky

John G Rell, Jr

Robert Allen Cordes

David A Campbell

James Wilson Bishop

Kimberly Marie Fernsler

Thomas L Jeremiah

Raymond J Eberhard

Jafar Nahidi

Brian Chen

Sheryll H Veneracion

Samuel David Kirchhoff

Translation lookaside buffer (TLB) invalidation using virtual addresses is provided. A cache is searched for a virtual address matching the input virtual address. Based on a matching virtual address in the cache, the corresponding cache entry is invalidated. The load/store queue is searched for a set and a way corresponding to the set and the way of the invalidated cache entry. Based on an entry in the load/store queue matching the set and the way of the invalidated cache entry, the entry in the load/store queue is marked as pending. Indicating a completion of the TLB invalidate instruction is delayed until all pending entries in the load/store queues are complete.

Dynamic translation lookaside buffer (TLB) invalidation using virtually tagged cache for load/store operations

Recovery circuits react to errors in a processor core by waiting for an error-free completion of any pending store-conditional instruction or a cache-inhibited load before ceasing to checkpoint or backup progress of a processor core. Recovery circuits remove the processor core from the logical configuration of the symmetric multiprocessor system, potentially reducing propagation of errors to other parts of the system. The processor core is reset and the checkpointed values may be restored to registers of the processor core. The core processor is allowed not just to resume execution just prior to the instructions that failed to execute correctly the first time, but is allowed to operate in a reduced execution mode for a preprogrammed number of groups. If the preprogrammed number of instruction groups execute without error, the processor core is allowed to resume normal execution.

Processor instruction retry recovery

A method of checkpointing a microprocessor by providing, in parallel, a current read value from a queue and a next read value from the queue, and then selectively passing one of the current read value and next read value to a capture latch based on an instruction completion signal. The capture latch can directly drive the checkpoint register circuitry in the recovery unit of the microprocessor. If the queue is empty, a pair of multiplexers connected to the input of the register queue array are used to pass the input data value. The instruction completion signal may indicate whether all instructions in an instruction group have successfully completed.

Method and apparatus to launch write queue read data in a microprocessor recovery unit

A method and apparatus are provided for dispatch group checkpointing in a microprocessor, including provisions for handling partially completed dispatch groups and instructions which modify system coherent state prior to completion. An instruction checkpoint retry mechanism is implemented to recover from soft errors in logic. The processor is able to dispatch fixed point unit (FXU), load/store unit (LSU), and floating point unit (FPU) or vector multimedia extension (VMX) instructions on the same cycle. Store data is written to a store queue when a store instruction finishes executing. The data is held in the store queue until the store instruction is checkpointed, at which point it can be released to the coherently shared level 2 (L2) cache.

Method for checkpointing instruction groups with out-of-order floating point instructions in a multi-threaded processor

A method and apparatus are provided for reducing the number of cycles required to checkpoint instructions in a multi-threaded microprocessor that has dispatch group checkpointing. A determination is made in a first stage of a checkpoint pipeline whether checkpointing can occur for a group of instructions. The results of processing the group of instructions flow to a second stage of the checkpoint pipeline regardless of whether the group of instructions is ready to checkpoint. If the group of instructions is ready to checkpoint, the group of instructions is checkpointed in a third stage of the checkpoint pipeline.

Method and apparatus for reducing number of cycles required to checkpoint instructions in a multi-threaded processor

A method for creating precise exceptions including checkpointing an exception causing instruction. The checkpointing results in a current checkpointed state. The current checkpointed state is locked. It is determined if any of a plurality of registers require restoration to the current checkpointed state. One or more of the registers are restored to the current checkpointed state in response to the results of the determining indicating that the one or more registers require the restoring. The execution unit is restarted at the exception handler or the next sequential instruction dependent on whether traps are enabled for the exception.

System and method for creating precise exceptions

An instruction processing unit (IPU) and a storage array, a storage-to-instruction-processing-unit interface, including a hardware accelerator for cross-boundary storage access with a cross-boundary buffer for providing residual read and write data in support of high speed block concurrent accessing of multi-word operands of a computer system. A cross-boundary buffer (CBB) is used, coupled to a write rotating shifter, a write merger (WMERGE) and a write merge controller (WMCTL) which is coupled for an input to said control register (CREG) for sequencing data transmitted on the data bus for merger with data contained in the cross-boundary buffer (CBB) by the write merger before it is latched in a data bus out register, and for simultaneously also latching the data in the cross-boundary buffer (CBB), and for writing data from the data bus out register into the storage array in the next clock cycle of the instruction processor at the doubleword address addressed. The cross-boundary buffer (CCB) is also coupled to a read rotating shifter (RROTATE), a read merger (RMERGE) and a read merge controller which responds to control instruction sequencing. The storage-to-instruction-processing-unit interface operates on multiple words, with residues from a second and subsequent accesses allowing continuation of the accessing process beyond two memory words. The hardware can repeat a second microword until an operand of arbitrary length is transferred. The interface permits efficient data transfer to be interrupted and resumed at a desired point, for efficient execution of Load Multiple and Store Multiple operations.

Computer system accelerator for multi-word cross-boundary storage access

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Round Rock, TX, United States of America

Michael James Mack