  Many applications heavily use bitwise operations on large bitvectors as part
of their computation. In existing systems, performing such bulk bitwise
operations requires the processor to transfer a large amount of data on the
memory channel, thereby consuming high latency, memory bandwidth, and energy.
In this paper, we describe Ambit, a recently-proposed mechanism to perform bulk
bitwise operations completely inside main memory. Ambit exploits the internal
organization and analog operation of DRAM-based memory to achieve low cost,
high performance, and low energy. Ambit exposes a new bulk bitwise execution
model to the host processor. Evaluations show that Ambit significantly improves
the performance of several applications that use bulk bitwise operations,
including databases.
