Remote Atomic Floating-Point Instructions for Lower Serialization
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Solution Overview
Problem
Existing multi-core processor systems face inefficiencies in executing atomic memory operations due to long latencies, high cache pressure, and throughput limitations, particularly in contended memory locations, leading to poor performance and serialization issues.
Innovation Solution
Implementing Remote Atomic Operations (RAO) instructions that allow execution in various locations within the processor, including cores, private caches, shared caches, cache control circuits, memory controllers, or remote cores, with weakly ordered memory accesses to reduce latency and serialization, and optimize execution based on performance, power, and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional atomic memory operations are executed in multi-core systems with contention, then correctness is maintained, but latency increases significantly and throughput decreases
Solution Approach 1:
The patent segments the atomic operation execution across multiple locations including home agent, cache, and remote core, allowing the operation to be divided into smaller sub-operations that can be executed in parallel or pipelined, thereby reducing overall latency while maintaining atomicity through coordinated execution
Solution Approach 2:
The patent introduces an intermediary mechanism where a remote core acts as a mediator to execute atomic operations on behalf of the requesting core. This intermediary approach allows the operation to bypass traditional coherence protocols and cache arbitration, reducing latency while ensuring correctness through the intermediary's coordinated execution
2Reliability
If traditional atomic memory operations are executed in multi-core systems, then atomicity is ensured, but throughput is limited due to serialization
Solution Approach 1:
The patent segments atomic operations into multiple executable units that can be distributed across different cores and cache levels, enabling parallel processing of multiple atomic operations simultaneously. This segmentation allows throughput improvement by eliminating the serialization bottleneck while maintaining atomicity through coordinated execution of segmented operations
Solution Approach 2:
The patent implements a universal atomic operation execution mechanism that can operate at multiple levels (home agent, cache, remote core) and handle different types of atomic operations (read-modify-write, compare-and-swap, etc.). This multi-functionality allows the system to optimize throughput by selecting the most appropriate execution location based on operation characteristics and system state
3Ease of operation
If atomic operations are executed at the core level, then control is precise, but cache pressure increases and performance decreases
Solution Approach 1:
The patent extracts the atomic operation execution from the core level and relocates it to alternative locations such as the home agent or cache. This extraction removes the operation from the core's execution path, reducing cache pressure and improving performance while maintaining precise control through dedicated execution units at the alternative locations
4Loss of time
If atomic operations are executed remotely, then latency is reduced and throughput improves, but system complexity increases
Solution Approach 1:
The patent implements a universal remote execution mechanism that can operate at multiple locations (home agent, cache, remote core) using a unified interface and protocol. This universality allows the system to achieve reduced latency and improved throughput through remote execution while managing complexity by providing a standardized, location-agnostic execution model that simplifies the interface between components
Data Source
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AI summary
Embodiments relate to atomic memory operations with floating point values. An example processor comprises: a control register to store rounding mode and denormal mode control bits to indicate a rounding mode and denormal value processing mode; fetch circuitry to fetch a remote atomic operation (RAO) floating point (FP) instruction comprising a memory location to store at least one FP result value; decode circuitry to decode the instruction and scheduling circuitry to offload the instruction to an execution engine external to the logical processor or to schedule the decoded instruction for local execution, wherein an indication of the rounding mode and denormal value processing mode is communicated to the execution engine, the indication to be communicated by a transfer of one or more of the rounding mode control bits and denormal mode control bits to a storage coupled to the execution engine, or to be communicated in the message.