Smart NIC Time Sync Control for Multi-Host Timestamp Alignment
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Solution Overview
Problem
Existing time distribution methods in System on a Chip (SoC) for network interfaces lack efficient mechanisms to maintain frequency and phase alignment of primary timers across various accelerator blocks, which is crucial for accurate timestamping and latency measurements in 5G wireless Radio Access Network applications.
Innovation Solution
Implementing a network intellectual property block in the data plane to provide synchronization signals for the main timer, allowing programmable adjustments through a 2-bit i_sync signal over a 2-wire interface, enabling real-time fine or coarse timing changes based on network constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If control plane time synchronization protocol is used with host or CPU control, then system architecture is simple and easy to implement, but timing accuracy and synchronization precision deteriorate due to control plane overhead
Solution Approach 1:
The patent introduces a dedicated time synchronization unit as an intermediary component that operates independently from the control plane. This unit receives timing signals directly from the primary timer and distributes them to accelerator blocks without requiring host or CPU intervention, thereby maintaining nanosecond-level accuracy while simplifying the control architecture.
Solution Approach 2:
The time synchronization system is designed to be self-sufficient by implementing an autonomous time distribution mechanism within the smart NIC. The primary timer and distribution points automatically maintain frequency and phase alignment without external control plane management, enabling the system to serve its own timing needs with high precision.
2Area of stationary object
If primary timer is distributed to multiple accelerator blocks, then time distribution coverage is improved, but frequency and phase alignment becomes difficult to maintain
Solution Approach 1:
The patent implements a feedback mechanism where distribution points continuously monitor their synchronization status with the primary timer and automatically adjust their timing to maintain frequency and phase alignment. This closed-loop control ensures that even as the system scales to multiple accelerator blocks, all distribution points remain precisely synchronized.
Solution Approach 2:
The time distribution system is designed to be dynamic and adaptive, allowing distribution points to automatically adjust their timing parameters in real-time. This dynamic capability enables the system to maintain synchronization accuracy across multiple accelerator blocks despite variations in signal propagation delays and timing drift.
3Adaptability or versatility
If more distribution points are added to support multiple hosts, then system versatility is improved, but maintaining synchronization across all points becomes more complex
Solution Approach 1:
The patent segments the time distribution system into independent, self-synchronizing units that can operate autonomously. Each distribution point is designed as a modular component that maintains synchronization with the primary timer independently, allowing the system to scale to multiple hosts without proportionally increasing synchronization complexity.
Solution Approach 2:
The time distribution architecture is designed with universal components that can serve multiple functions and multiple hosts simultaneously. The primary timer and distribution points are configured to provide timing services to various accelerator blocks and host interfaces through a unified synchronization mechanism, eliminating the need for separate synchronization systems for each host.
Data Source
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AI summary
Methods and apparatus for data plane control of network time sync protocol in multi-host systems. A network interface controller (NIC) is configured to implement a network data plane that is associated with a software-based control plane implemented in the multi-host system. The NIC includes a primary timer and secondary timers at distributed endpoints such as network ports. The NIC receives network time packets having network timestamps and employs a secondary timer to associate a local timestamp with the packets. The network and local timestamps are compared by a network intellectual property block (network IP) in the data plane datapath to adjust the primary and secondary timer(s) to match the network time. The network IP uses a 2-bit wire protocol to increment and/or decrement the primary and secondary timer(s) that enables the timers to be adjusted with a nanosecond granularity.