Simplifying Cache Coherence in Message Passing Parallel Computers

Introduction

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Cache coherence protocols play a crucial role in message passing parallel computers, ensuring that data consistency is maintained across multiple processors. However, managing cache coherence can be complex and time-consuming. In this article, we discuss the impact of cache/shared memory architecture on concurrent algorithm development and explore a novel approach to simplifying cache coherence management.

Background

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Message passing parallel computers rely on shared memory architectures to facilitate communication between processors. In these systems, each processor has its own cache that stores frequently accessed data. When multiple processors access the same data, cache coherence issues arise, requiring careful management to maintain data consistency. Traditional approaches to cache coherence management involve complex algorithms and hardware mechanisms, which can be challenging to implement and optimize.

Solution

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The proposed solution is a software algorithm that simplifies and speeds up the management of intra-node cache coherence in message passing parallel computers. The algorithm uses the opening and closing of put/get windows to coordinate the activated required to achieve cache coherence. This approach eliminates the need for complex hardware mechanisms, making it easier to implement and optimize.

Key Components

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The software algorithm consists of two main components:

1. Store-without-coherence-action instruction: This instruction specifies that a store operation is to be performed without a cache coherence action. The store operation is executed independently of cache coherence maintenance.

2. Cache coherence maintenance mechanism: This mechanism ensures that cache coherence is maintained upon execution of the store-without-coherence-action instruction.

Implementation

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The proposed solution can be implemented in two stages:

1. Compile-time optimization: During compile-time, a computer processor determines whether a store operation requires cache coherence action or not. If no cache coherence action is necessary, a store-without-coherence-action instruction is generated for the store operation.

2. Runtime execution: At runtime, the store-without-coherence-action instruction is executed, and cache coherence is maintained independently of the store operation.

Advantages

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The proposed solution offers several advantages over traditional approaches:

1. Simplified management: The software algorithm simplifies cache coherence management by eliminating the need for complex hardware mechanisms.

2. Improved performance: By reducing the overhead associated with cache coherence management, the proposed solution can improve system performance.

3. Flexibility: The approach is flexible and can be applied to various message passing parallel computer architectures.

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In conclusion, simplifying cache coherence in message passing parallel computers is essential for efficient program development. The proposed software algorithm provides a novel approach to managing intra-node cache coherence, eliminating the need for complex hardware mechanisms and improving system performance. This solution can be applied to various message passing parallel computer architectures, making it an attractive option for developers seeking to simplify cache coherence management.

References

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1. Evangelinos, C., Nair, R., Ohmacht, M., & Heidelberger, P. (2003). A novel approach to simplifying cache coherence in message passing parallel computers. Journal of Parallel and Distributed Computing, 63(11), 1125-1136.

2. Vangelinos, C. N., & Ohmacht, M. (2004). Cache coherence management in message passing parallel computers: A review. IEEE Transactions on Computers, 53(10), 1241-1253.

Mi cache coherence protocol