Categorized Memory Operations for Selective Barrier Synchronization
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Solution Overview
Problem
Conventional computing systems face inefficiencies in launching processing work due to false dependencies created by host barriers waiting for all previous data and flags to be visible, leading to unnecessary delays and reduced computational performance, especially when setting a flag in remote memory takes significantly longer than storing data in host memory.
Innovation Solution
Implementing categorized memory operations and barrier instructions that allow for the launch of processing work without waiting for prior sets to complete, by specifying categories for memory operations and barrier instructions, enabling independent execution and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the host waits for all previous data and flags to be visible before launching processing work, then data consistency is ensured, but latency increases and computational performance decreases
Solution Approach 1:
The patent segments the memory operations into two distinct categories: host memory operations and remote memory operations. By applying different barrier semantics to each category, the system ensures data consistency for host memory while avoiding unnecessary waits for remote memory operations, thereby reducing latency without compromising reliability.
Solution Approach 2:
The patent applies different quality characteristics to different parts of the memory system. Host memory operations receive strong ordering guarantees with full barriers, while remote memory operations use relaxed ordering with selective barriers. This local differentiation allows the system to maintain consistency where needed while optimizing performance elsewhere.
2Stability of the object's composition
If the host waits for flag setting in remote memory before launching next work, then work ordering is maintained, but productivity decreases due to unnecessary delays
Solution Approach 1:
The patent segments the synchronization requirements by creating separate barrier instructions for host memory and remote memory. The categorized barrier only waits for host memory operations to complete, allowing remote memory flag setting to proceed asynchronously. This maintains work ordering for host operations while enabling parallel productivity gains from independent remote operations.
3Reliability
If conventional barrier instructions wait for all memory operations to complete, then memory visibility is ensured, but device complexity increases due to unnecessary synchronization
Solution Approach 1:
The patent divides memory operations into distinct categories (host memory vs. remote memory) and applies specialized barrier instructions for each. The categorized barrier instruction only synchronizes host memory operations, eliminating the need for complex full-system synchronization while maintaining necessary memory visibility guarantees for each category.
Data Source
AI summary
Various embodiments include techniques for launching processing work in a computing system. The disclosed techniques include load and store operations that specify a category. The disclosed techniques further include barrier instructions that specify a category. A processing unit of the computing system executes a set of load and store operations that specify various categories. When the processor subsequently executes a barrier instruction that specifies a category, the barrier instruction waits for data for only load and store operations that specify the same category. After the barrier instruction completes execution, the processing unit can launch processes that are dependent on data from load and store operations of the specified category, even if data from load and store operations of other categories is still pending. As a result, the processing unit can launch processes as soon as the relevant data is available without waiting for nonrelevant data.