Maximum Compare-and-Swap RDMO for Low-Latency Remote Memory
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Solution Overview
Problem
Existing network communication methods for performing complex operations in remote memory incur high latency and require remote host involvement, making them inefficient and suboptimal for distributed applications.
Innovation Solution
Implementing Remote Direct Memory Operations (RDMO) commands, such as Maximum Compare-and-Swap (MAX-CAS), Hash Table get/set, Table Append, and fault-tolerant remote logging, directly in the transport protocol between network devices, enabling atomic execution without host intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If existing network communication methods are used to perform complex operations in remote memory, then the operations can be executed with host involvement, but latency increases and efficiency decreases
Solution Approach 1:
The patent extracts the host involvement requirement from the remote memory operation execution process. By implementing compare-and-swap operations directly in network devices (NICs), the system eliminates the need for host CPU participation in these operations, thereby reducing latency while maintaining operational simplicity for the host.
Solution Approach 2:
The patent enables network devices to perform complex compare-and-swap operations autonomously without host intervention. The NICs self-service by executing the operations locally using their own resources, which reduces the time required for operation completion and eliminates host involvement overhead.
2Productivity
If complex operations are performed in remote memory through host involvement, then the operations can be executed, but communication overhead increases
Solution Approach 1:
The patent segments the remote memory operation execution into two parts: simple operations that can be handled by network devices and complex operations that require host involvement. By implementing compare-and-swap operations at the network device level, the system improves productivity for these specific operations while reducing communication overhead compared to handling all operations through the host.
3Reliability
If compare-and-swap operations are implemented in transport protocol, then atomic execution is achieved, but device complexity increases
Solution Approach 1:
The patent merges the compare-and-swap operation logic directly into the transport protocol layer of network devices. This integration ensures atomic execution of operations while managing device complexity by combining multiple functions (comparison, swapping, and network communication) into a unified protocol implementation rather than separate components.
Data Source
AI summary
A system includes a first network device and a second network device. The first network device is to send over a network a command that (i) specifies a memory location, a compare value and a swap value and (ii) instructs that the swap value be written into the memory location only if the compare value is larger than a current value in the memory location. The second network device is to receive the command over the network, and to execute the command by reading the current value from the memory location, comparing the current value to the compare value, and, upon finding that the compare value is larger than the current value, writing the swap value to the memory location in place of the current value.