REGISTER CHECKPOINTING MECHANISM FOR MULTITHREADING

• Main Authors: LATORRE FERNANDO, GONZALEZ ANTONIO, LOPEZ PEDRO, MADRILES CARLOS, MARTINEZ ALEJANDRO, CODINA JOSEP M, MARTINEZ RAUL, CODINA ENRIC GIBERT
• Format: Patent
• Language: English
• Published: 14.10.2010
• Subjects: CALCULATING; COMPUTING; COUNTING; ELECTRIC DIGITAL DATA PROCESSING; PHYSICS

Methods and apparatus are disclosed for using a register checkpointing mechanism to resolve multithreading mis-speculations. Valid architectural state is recovered and execution is rolled back. Some embodiments include memory to store checkpoint data. Multiple thread units concurrently execute threads. They execute a checkpoint mask instruction to initialize memory to store active checkpoint data including register contents and a checkpoint mask indicating the validity of stored register contents. As register contents change, threads execute checkpoint write instructions to store register contents and update the checkpoint mask. Threads also execute a recovery function instruction to store a pointer to a checkpoint recovery function, and in response to mis-speculation among the threads, branch to the checkpoint recovery function. Threads then execute one or more checkpoint read instructions to copy data from a valid checkpoint storage area into the registers necessary to recover a valid architectural state, from which execution may resume.