Ensuring Data Freshness for In-Storage Computing with Cooperative Buffer Manager

In-storage computing (ISC) aims to mitigate the excessive data movement between the host memory and storage by offloading computation to storage devices for in-situ execution. However, ensuring data freshness remains a key challenge for practical ISC. For performance considerations, many data processing systems implement a buffer manager to cache part of the on-disk data in the host memory. While the host applications commit updates to the in-memory cached copies of the data, ISC operators offloaded to the device only have access to the on-disk persistent data. Thus, ISC may miss the most recent updates from the host and produce incorrect results after reading the stale and inconsistent data from the persistent storage. With this limitation, current ISC can only be used in read-only settings where the on-disk data are not subject to concurrent updates. To tackle this problem, we propose a cooperative buffer manager for ISC to transparently provide data freshness guarantees to host applications. Proposed methods allow the device to synchronize with the host buffer manager and decide whether to read the most recent copy of data from host memory or flash memory. We implement our method based on a real hardware platform and perform evaluation with a Bs--tree based key-value store. Experiments show that our method can provide transparent data freshness for host applications with reduced latency.