International Business Machines Corporation

Colin B Blundell

Maged M Michael

Harold Wade Cain, Iii

Gheorghe Calin Cascaval

A method, a system and a computer program product for handling speculative stores. The system determines when a speculative store buffer is not full. An indicator is generated when the speculative store buffer is not full, and the speculative stores are input into the speculative store buffer. When the speculative store buffer is full, a full buffer indicator is generated. Speculative stores prevented from entering the speculative store buffer are overflow stores. The overflow list is searched to determine whether one or more addresses of the overflow stores are present in the overflow list. When one or more addresses of the overflow stores are not present in the overflow list, the overflow stores are stored in the overflow list.

Overflow handling of speculative store buffers

A method, system and computer program product for issuing one or more software initiated operations for creating a checkpoint of a register file and memory, and for restoring a register file and memory to the checkpointed state. At the execution of a checkpoint operation, the system returns a condition code indicating success or failure. When the condition code is set equal to one, one or more checkpoints are initiated. Contents of the register file and gated store buffer are stored each time the one or more checkpoints are initiated. When the checkpoint is created, the system notifies software when a hardware checkpoint capacity has been reached. One or more of the software checkpoint, hardware checkpoint, and handler checkpoint are utilized to provide a more precise point of restoration. During software execution, the register file and gated store buffer can be restored as defined by the one or more previous checkpoints.

System and method for software initiated checkpoint operations

Mechanisms for performing predicated atomic commits based on consistency of watches is provided. These mechanisms include executing, by a thread executing on a processor of the data processing system, an atomic release instruction. A determination is made as to whether a speculative store has been lost, due to an eviction of a memory block to which the speculative store is performed, since a previous atomic release instruction was processed. In response to the speculative store having been lost, invalidating, by the processor, speculative stores that have been performed since the previous atomic release instruction was processed. In addition, the method comprises, in response to the speculative store not having been lost, committing, by the processor, speculative stores that have been performed since the previous atomic release instruction was processed.

Growing community of inventors

West Allenhurst, NJ, United States of America

Colin B Blundell