Trace Unit Bias Promoting for Instruction Throughput

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Solution Overview

Problem

Current processor sequencing techniques do not meet the demands for improved performance and reduced power consumption, especially in portable devices, while maintaining backward compatibility with x86 instruction code.

Innovation Solution

A method and system for an improved trace unit that determines if a current trace is promotable and if a next trace is appendable, promoting them if so, to optimize instruction processing and reduce power consumption by efficiently sequencing operations ahead of the execution unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If current processor sequencing techniques are used, then backward compatibility with x86 instruction code is maintained, but instruction execution throughput is insufficient and power consumption is high

Engineering Contradiction:

Improveinstruction execution throughputVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent segments the instruction stream into traces, which are sequences of instructions that can be executed together. This segmentation allows the processor to process multiple instructions in parallel within each trace, significantly improving instruction execution throughput while maintaining the ability to execute x86 code. The trace-based approach enables finer-grained parallelism without sacrificing backward compatibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary actions by sequencing traces ahead of the execution unit's readiness. The trace unit can prepare and sequence traces in advance, then append them to the execution queue when the execution unit is ready. This allows the processor to maintain high throughput by having traces ready to execute without waiting for the execution unit, while power consumption is reduced by avoiding unnecessary sequencing operations when the execution unit is busy.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If traces are sequenced ahead of the execution unit, then instruction execution throughput is improved, but trace cache management complexity increases

Engineering Contradiction:

Improveinstruction execution throughputVSAvoidtrace cache management complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements dynamic trace cache management by adjusting the promotion threshold based on current processor state and trace characteristics. The promotion threshold is not fixed but can be dynamically adjusted to optimize the balance between throughput improvement and cache management complexity. This allows the system to adapt to varying workloads and execution conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes key parameters such as the promotion threshold and trace appending conditions to optimize performance. By adjusting these parameters dynamically, the system can improve instruction execution throughput while keeping trace cache management complexity within acceptable limits. The parameter changes allow the trace unit to adapt to different execution scenarios and maintain optimal operation.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If a promotion threshold is used to determine trace promotability, then trace sequencing efficiency is improved, but traces with high bias values may be incorrectly rejected

Engineering Contradiction:

Improvetrace sequencing efficiencyVSAvoidtrace selection accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary actions by checking whether a trace's bias value meets or exceeds the promotion threshold before attempting to append it to the execution queue. This preliminary check ensures that only traces with sufficient bias (indicating high likelihood of correct execution) are considered for promotion. The bias value itself serves as a pre-computed indicator of trace reliability, allowing efficient filtering while maintaining accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent incorporates feedback mechanisms where the bias value is updated based on trace execution outcomes. When traces are executed, the results feed back into the bias value calculation, allowing the system to learn from past performance and adjust future promotion decisions. This feedback loop ensures that traces with high bias values are reliably selected, preventing incorrect rejections while maintaining sequencing efficiency.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS7814298B1Promoting and appending traces in an instruction processing circuit based upon a bias value

Publication Date: 2010.10.12 SUN MICROSYSTEMS INC

AI summary

A method, system and computer program product for promoting a trace in an instruction processing circuit is disclosed. They comprise determining if a current trace is promotable and determining if a next trace is appendable to the current trace. They include promoting the current trace and the next trace if the current trace is promotable and the next trace is appendable.