Threshold controlled limited out of order load execution
AssigneeApplied Micro Circuits Corporation
InventorsMatthew W. Ashcraft, John Gregory Favor
Life of this patent
Estimating the term…
Abstract
A load scheduler capable of limited issuing of out of order load instruction is disclosed. The load scheduler uses a max skipping threshold which limits the number of skipping load instructions and a max skipped threshold which limits the number of skipped load instructions. An address tag for a skipping instruction is stored in a skipping load instruction tracking unit when a skipping load instruction is issued. When a skipped load instruction issues, the address tag of the skipped load instruction is compared to the address tag of the skipping instruction to determine if a hazard from the out of order issuing of the skipping load instruction caused a hazard and must be flushed.
Claims40
A method of scheduling a plurality of ordered load instructions from a first processing unit, comprising:
- waiting for a ready load instruction;
- determining whether the ready load instruction is a skipping instruction;
- calculating a number of skipping instructions when the ready load instruction issues;
- stalling the ready load instruction when the number of skipping instructions exceeds a max skipping threshold;
- calculating a number of skipped instructions when the ready load instruction issues;
- stalling the ready load instruction when the number of skipped instructions exceeds a max skipped threshold;
- issuing the ready load instruction when the number of skipping instructions does not exceed the max skipping threshold and the number of skipped instructions does not exceed the max skipped threshold.
A system for scheduling a plurality of ordered load instructions from a first processing unit, comprising:
- the first processing unit configured for facilitating performance of operations, comprising:
- waiting for a ready load instruction;
- determining whether the ready load instruction is a skipping instruction;
- calculating a number of skipping instructions when the ready load instruction issues;
- stalling the ready load instruction when the number of skipping instructions exceeds a max skipping threshold;
- calculating a number of skipped instructions when the ready load instruction issues;
- stalling the ready load instruction when the number of skipped instructions exceeds a max skipped threshold;
- issuing the ready load instruction when the number of skipping instructions does not exceed the max skipping threshold and the number of skipped instructions does not exceed the max skipped threshold.
Dependencies are inferred from the claim text.