COUNTING SPECULATIVE AND NON-SPECULATIVE EVENTS

摘要

Counting events during the execution of one or more instructions in a computer system may be accomplished by maintaining a non-speculative counter for counting events occuring in non-speculative instructions, as well as a separate speculative counter for counting events occuring in speculative instructions. Event counters may be used to count individual events occuring during the processing of instructions. When the instruction has been completed, the amount in the event counter corresponding to a particular event for that isntruction is added to the amount in the speculative counter corresponding to the event. Then, any retirable instructions are retired. Once an instruction is retired, it is no longer speculative, allowing the amount in the speculative counter to be incremented by the amount in any event counters corresponding to retirable instructions. The speculative and non-speculative counters may then be examined at any point in time to give a clear picture of the number of times a specific event has occured, even when instructions are executed out-of-order.