Energy-optimal caches with guaranteed lifetime

Abstract

This work addresses the aging of the memory sub-system due to NBTI (Negative Bias Temperature Instability) in systems that have to provide a guaranteed level of service, and specifically, a guaranteed lifetime. Our approach leverages a novel cache architecture in which a smart joint use of redundancy and power management allows us to obtain caches that meet a desired lifetime target with minimal energy consumption. This is made possible by exploiting the possibility of putting the cache sub-block used for redundancy into a deep low-power state, thus allowing more energy saving than a regular architecture. Sacrificing a portion of the cache for aging mitigation only marginally affects performance thanks to the non-linear dependency of miss rate versus cache size, which allows to find the best cache size that maximizes the objective. Simulation results show that it is possible to meet the target lifetime by achieving energy reductions (measured over the lifetime of the system) ranging from 3X to 10X (2X to 8X) for a lifetime target of 15 (25) years, with marginal miss rate overhead.

ARGO: Aging-aware GPGPU register file allocation

“…Recent approaches have also proposed NBTI-aware power-gating [10], [11], [17] that exploits a circuit's sleep state that is intrinsically immune to aging. It has been used for inactive portion of the cache to meet a given lifetime target [11].…”

“…It has been used for inactive portion of the cache to meet a given lifetime target [11]. An orthogonal problem is aging of PMOS sleep-transistors which is critical to lifetime of whole system.…”

“…However, these post-silicon reliability techniques rely on reactive measures (e.g., error detection and error correction) with inevitable overhead. For controllability, power-gating is deployed as an effective technique to mitigate NBTI-induced aging [10], [11], [17]; power-gating achieves intrinsic protection against NBTI by providing sleep states that spare gates from stress that induce NBTI effects.…”