Switched Protocol Transformer for Multi-Host CXL Accelerator Sharing
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Solution Overview
Problem
Current PCIe and CXL interconnect technologies limit the flexibility and resource utilization in computing systems by constraining accelerators to a single host, preventing true sharing among multiple hosts and independent processing contexts.
Innovation Solution
Implementing a switch with multiple Virtual Compute Express Link (CXL) Switches (VCSs) and Resource Provisioning Units (RPUs) to establish multiple communication routes, allowing accelerators to be shared among multiple hosts and enabling integrated, cooperative operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a CXL accelerator is connected to a single Root Port on one host, then the accelerator can be reliably accessed by that host, but the accelerator cannot be shared among multiple hosts simultaneously
Solution Approach 1:
A CXL switch acts as an intermediary component between multiple hosts and a single accelerator. The switch receives requests from multiple hosts and routes them to the accelerator through a hierarchical domain structure, enabling the accelerator to be shared among multiple hosts while maintaining stable connections through the switch's routing tables
Solution Approach 2:
The patent introduces a hierarchical domain structure that adds a new dimension to the traditional direct host-accelerator connection. By organizing connections through multiple levels (host -> CXL switch -> hierarchical domain -> accelerator), the system enables multi-host access without compromising the stability of individual host-accelerator communication paths
2Adaptability or versatility
If multiple hosts access shared memory through CXL, then resource sharing is enabled, but the hosts cannot simultaneously share the same accelerator or processing context
Solution Approach 1:
The patent segments the accelerator access path into distinct hierarchical domains managed by CXL switches. Each host has its own hierarchical domain that can independently manage its processing context, while still sharing the common accelerator resource through the switch infrastructure, thus reducing overall system complexity
3Adaptability or versatility
If traditional PCIe/CXL switches are used, then devices can be connected in hierarchical topology, but the routing is limited to single-path and cannot support multiple simultaneous communication routes
Solution Approach 1:
The patent implements dynamic routing capabilities in the CXL switch that allow it to establish multiple communication routes simultaneously. The switch can dynamically select different paths based on real-time conditions, enabling flexible multi-path routing between hosts and accelerators without requiring complex static configuration
Data Source
AI summary
Embodiments for communicating using a switch configured to establish multiple types of communication routes. First and second upstream switch ports (USPs) communicate with first and second hosts according to first and second Compute Express Link (CXL) protocols, respectively. A downstream switch port (DSP) communicates with a device according to a third CXL protocol. The switch couples the first USP to the DSP via a first route traversing a single Virtual CXL Switch (VCS), and couples the first USP to the second USP via a second route traversing two VCSs. Optionally, the switch includes a Resource Provisioning Unit (RPU) coupling the two VCSs of the second route, terminating the first and second CXL protocols, and translating between CXL messages conforming to the first and second CXL protocols.