Load lookahead prefetch for microprocessors
US7594096B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 5, 2007 |
| Grant date | Sep 22, 2009 |
| Priority date | — |
| Expiry date | Mar 11, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/3851
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The present invention allows a microprocessor to identify and speculatively execute future load instructions during a stall condition. This allows forward progress to be made through the instruction stream during the stall condition which would otherwise cause the microprocessor or thread of execution to be idle. The data for such future load instructions can be prefetched from a distant cache or main memory such that when the load instruction is re-executed (non speculative executed) after the stall condition expires, its data will reside either in the L1 cache, or will be enroute to the processor, resulting in a reduced execution latency. When an extended stall condition is detected, load lookahead prefetch is started allowing speculative execution of instructions that would normally have been stalled. In this speculative mode, instruction operands may be invalid due to source loads that miss the L1 cache, facilities not available in speculative execution mode, or due to speculative instruction results that are not available via forwarding and are not written to the architected registers. A set of status bits are used to dynamically keep track of the dependencies between instruct…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.