Cache Oblivious Binary Search

29 Dec 2016

The goal of Cache Oblivious algorithms is to efficiently use data in a CPU cache and reduce unnecessary swapping of data between slow to fast memory. The big win of a cache oblivious algo is that this efficiency works at any level of a memory hierarchy, e.g. from RAM to CPU cache or from Hard Disk to RAM.

We attempt to implement a cache oblivious binary search using ideas from the paper: “Cache Oblivious Search Trees via Binary Trees of Small Height” by Brodal, Fagerberg, and Jacob. Included is an implementation to convert a binary search tree from an implicit inorder layout to implicit van Emde Boas layout.

Initial results are promising, cache misses for a van Emde Boas based search are lower than inorder.

However, the running time of the van Emde Boas based search is higher. We suspect this may be due to the non-trivial overhead of traversing a vEB tree.

Link to code: