Limited Access: The Truth Behind Far Memory

Memory capacity in data centers is becoming a scarce resource. To address this issue, emerging runtimes enable applications to supplement their local memory with additional tiers of compressed, non-volatile, or far memory, often accessed via OS-supported paging. In these systems, minimizing page faults is crucial for good performance. Yet, there is little common understanding of which parts of application code are responsible for triggering page faults. In this paper, we analyze page-fault behavior across a suite of 26 applications and find that the vast majority of page faults are triggered by a very small number of lines of application code. In the light of this and related observations, we discuss the feasibility of several ways to reduce page faults.