Isle-Tree: A B+-Tree with Intra-Cache Line Sorted Leaves for Non-volatile Memory

Byte-addressable non-volatile memory (NVM) is to reshape computer systems. Researchers have proposed crash-consistent in-NVM Bs+-trees with unsorted or sorted nodes to store key-value (KV) pairs. However, they still yield suboptimal performance: inserting a KV pair into a sorted node shifts numerous KV pairs that may cause multiple cache lines to be flushed, while to search a KV pair in an unsorted node is inefficient. In this paper, we propose Isle-Tree. Each cache line of Isle-Tree's leaf node is sorted while the node is unsorted. For most insertions/deletions, Isle-Tree flushes only one cache line of KV pairs. For searches, sorted cache lines help Isle-Tree avoid unnecessary comparisons. Experiments show that Isle-Tree yields high performance for all insertions, deletions and searches.