Dynamic Binary Adaptation for Speculative Prefetching

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Solution Overview

Problem

Existing multi-threading techniques in information processing systems, such as SMT, do not effectively optimize overlap of resource inefficiencies like branch mispredictions and instruction dependencies, leading to performance penalties during cache misses or long latency operations.

Innovation Solution

A dynamic binary adaptation method is introduced, where a compiler dynamically identifies and generates a helper thread to perform speculative prefetching, embedding it into the main thread's binary to prevent cache misses by computing and scheduling execution slices to optimize slack and reduce latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If simultaneous multi-threading is used to improve processor performance, then resource utilization is improved, but performance penalties occur during cache misses or long latency operations

Engineering Contradiction:

Improveprocessor performanceVSAvoidcache miss latency

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The invention creates a helper thread that performs preliminary actions by speculatively prefetching data before the main thread actually needs it. The helper thread computes address sequences and issues memory requests in advance, attempting to have data ready before cache misses occur, thereby reducing the latency penalty when the main thread requires the data.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The helper thread acts as an intermediary between the main thread and the memory system. It mediates memory access by performing speculative prefetching operations, computing address sequences, and managing memory requests independently, thereby shielding the main thread from cache miss penalties and long latency operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of time

If helper threads are dynamically created to perform speculative prefetching, then cache miss latency is reduced, but binary code complexity increases

Engineering Contradiction:

Improvecache miss latencyVSAvoidbinary code structure

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The binary code is segmented into distinct functional components: the main thread for primary computation and helper threads for speculative prefetching. This segmentation allows independent optimization of each thread's functionality, with helper threads containing specialized code for address sequence computation and memory request issuance, thereby managing complexity through modular organization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically creates and manages helper threads based on runtime conditions rather than using static predetermined structures. The compiler generates code that can dynamically spawn helper threads when speculative prefetching is beneficial, and the helper threads themselves dynamically compute address sequences and manage their execution, providing adaptability to reduce latency without requiring complex static binary structures.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8095920B2Post-pass binary adaptation for software-based speculative precomputation

Publication Date: 2012.01.10 INTEL CORP

AI summary

The latencies associated with cache misses or other long-latency instructions in a main thread are decreased through the use of a simultaneous helper thread. The helper thread is a speculative prefetch thread to perform a memory prefetch for the main thread. The instructions for the helper thread are dynamically incorporated into the main thread binary during post-pass operation of a compiler.