RDMA Cache Lease Management for Access Pattern Tracking
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Solution Overview
Problem
In Remote Direct Memory Access (RDMA) data stores, the host computer lacks awareness of access frequencies of data items, leading to undesired evictions when traditional cache management algorithms are used, and informing remote computers of all accesses would reduce performance benefits.
Innovation Solution
Implementing a lease system with local and remote expiration times for data items, allowing remote computers to access data via RDMA reads until the expiration time, while the host computer maintains a global view of access patterns and updates lease terms based on access history.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If traditional cache management algorithms (e.g., LRU, CLOCK) are used, then cache eviction decisions can be made automatically, but undesired evictions occur because the host computer lacks awareness of access frequencies
Solution Approach 1:
The patent introduces remote pointers as an intermediary mechanism that allows the host computer to indirectly track access frequencies without direct notification from remote computers. The remote pointer contains a remote expiration time that is updated based on RDMA read operations, providing the host with visibility into access patterns while maintaining RDMA performance benefits
Solution Approach 2:
The system implements feedback through the remote pointer mechanism, where the remote expiration time is dynamically updated based on access patterns. This feedback loop allows the host computer to adjust cache management decisions based on actual usage data without requiring direct communication from remote computers about each access
2Loss of information
If remote computers inform the host computer of all cache data accesses, then the host can track access frequencies accurately, but a large number of messages are generated that reduce RDMA performance benefits
Solution Approach 1:
The patent extracts the access tracking information from the RDMA data transfer path itself. By embedding access frequency data in the remote pointer's expiration time field, the system separates information gathering from the high-performance data path, avoiding additional messaging overhead while still capturing access patterns
Solution Approach 2:
The system uses the remote pointer as a copy mechanism that reflects access patterns without requiring direct communication. The remote expiration time is updated based on RDMA read operations, creating a passive copy of access frequency information that the host can use for cache management without interfering with the primary data transfer function
Data Source
AI summary
Embodiments relate to methods, systems and computer program products for cache management in a Remote Direct Memory Access (RDMA) data store. Aspects include receiving a request from a remote computer to access a data item stored in the RDMA data store and creating a lease including a local expiration time for the data item. Aspects further include creating a remote pointer to the data item, wherein the remote pointer includes a remote expiration time and transmitting the remote pointer to the remote computer, wherein the lease is an agreement that that the remote computer can perform RDMA reads on the data item until the remote expiration time.