Synchronous Coalesced Access via Silicon Photonics
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Solution Overview
Problem
Existing computer architectures face inefficiencies and high energy utilization due to electrical interconnect latency, lack of synchronization, and difficulty in parallel programming of many-core systems, especially with non-local data access patterns.
Innovation Solution
A multi-processor system with a global synchronization framework using silicon photonics and Synchronous Coalesced Access (SCA) instructions for simultaneous operation across all processor cores, enabling efficient data reorganization and synchronization through photonic waveguides or electrical connectivity, allowing for globally synchronous cooperative load and store operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If electrical interconnect is used for processor communication, then device complexity is reduced, but latency increases and synchronization becomes difficult
Solution Approach 1:
The patent replaces electrical interconnect with optical interconnect (silicon photonics) to transmit data between processors. This substitution eliminates the fundamental limitation of electrical signals in achieving synchronous operation across multiple cores, as optical signals can be precisely timed and synchronized, thereby resolving the latency and synchronization issues while maintaining system complexity at an acceptable level.
Solution Approach 2:
The patent changes the fundamental parameter of signal transmission from electrical to optical domain. By using photonic waveguides and optical modulators, the system achieves precise control over signal timing and synchronization, enabling lock-step operation across processor cores that is impossible with electrical interconnect alone.
2Productivity
If more processor cores are added to increase parallelism, then productivity increases, but synchronization difficulty increases and energy utilization worsens
Solution Approach 1:
The patent segments the interconnect system into photonic waveguides that dedicatedly connect processor cores, enabling independent yet synchronized operation of each core. This segmentation allows each processor to operate autonomously on its data while maintaining global synchronization through the optical interconnect, thereby scaling productivity without proportionally increasing energy consumption.
Solution Approach 2:
The patent introduces photonic waveguides and optical modulators as intermediary components between processor cores. These intermediaries enable efficient communication and synchronization without the energy overhead of electrical interconnect, allowing the system to scale to many cores while maintaining energy efficiency through the low-power optical transmission medium.
3Adaptability or versatility
If data is accessed from non-local memory locations, then adaptability increases, but access time increases due to latency
Solution Approach 1:
The patent replaces electrical signal transmission for memory access with optical signal transmission through photonic waveguides. This substitution enables fast access to non-local memory locations by eliminating the latency inherent in electrical interconnect, thereby maintaining data access flexibility while reducing access time through the superior speed and timing precision of optical transmission.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly enhances parallel efficiency by removing latency uncertainties in interconnects and memory subsystems, enabling processors to operate in lock-step with high efficiency and optimizing memory usage, particularly in dense processing loads with low data locality.
Implementation Method 1
the addition of silicon photonics to the architect's technological toolbox is shown to enable scalable parallel efficiency
Implementation Method 2
The data may be reorganized in-flight in a photonic waveguide and/or using photonic synchronization (P-Sync)
Data Source
AI summary
Global synchrony changes the way computers can be programmed. A new class of ISA level instructions (the globally-synchronous load-store) of the present invention is presented. In the context of multiple load-store machines, the globally synchronous load-store architecture allows the programmer to think about a collection of independent load-store machines as a single load-store machine. These ISA instructions may be applied to a distributed matrix transpose or other data that exhibit a high degree of data non-locality and difficulty in efficiently parallelizing on modern computer system architectures. Included in the new ISA instructions are a setup instruction and a synchronous coalescing access instruction (“sca”). The setup instruction configures a head processor to set up a global map that corresponds processor data contiguously to the memory. The “sca” instruction configures processors to block processor threads until respective times on a global clock, derived from the global map, to access the memory.