Enabling energy efficient Hybrid Memory Cube systems with erasure codes

Abstract

The Hybrid Memory Cube (HMC) is a promising alternative to DDRx memory due to its potential to achieve significantly higher bandwidth. However, the high static power of an HMC device compromises power efficiency when the device is lightly utilized. Activating a sleeping HMC takes over 2µs, which makes it challenging to manage HMC power without a substantial degradation in system performance. We introduce a new technique that alleviates the long wakeup penalty of an HMC by employing erasure codes. Inaccessible data stored in a sleeping HMC module can be reconstructed by decoding related data retrieved from other active HMCs, rather than waiting for the sleeping HMC module to become active. This approach makes it possible to tolerate the latency penalty incurred when switching an HMC between active and sleep modes, thereby enabling a power-capped HMC system. Simulations show that the proposed architecture outperforms a current HMC-based multicore system by 6.2×, and reduces the system energy by 5.3× under the same power budget as the multicore baseline.