FusedCache: A Naturally Inclusive, Racetrack Memory, Dual-Level Private Cache
FusedCache: A Naturally Inclusive, Racetrack Memory, Dual-Level Private Cache
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FusedCache：天生包容、赛道内存、双层私有缓存
DOI：
10.1109/tmscs.2016.2536020
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
A. Jones
中科院分区：
文献类型：
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作者：
Haifeng Xu;Y. Alkabani;R. Melhem;A. Jones
我们提出了 FusedCache，这是一种两级组关联 Racetrack 内存 (RM) 缓存设计，利用 RM 的高密度在一级提供快速统一访问，在下一级提供非统一访问。 FusedCache 非常适合私有 L1/L2 缓存，强制 L1 数据与 RM 访问点对齐，其余未对齐数据用作 L2。它使用传统的 LRU 逐出来处理 L1 未命中。 L1 和 L2 之间的升级和降级通过轮班进行，必要时还可以进行后台交换操作。这些交换操作不需要物理存储或负载，从而使访问更快、更节能。此外，与传统的包容性缓存层次结构不同，融合的 L1 缓存线自然存在于 L2 中，避免了重复的存储和标签结构、提升和驱逐。每个轨道上的 L1 状态通过轨道 LRU 维护和后台交换严格执行。我们的结果表明，与等区域 L1 SRAM 缓存替代相比，FusedCache 将应用程序性能提高了 7%，同时将缓存能耗降低了 33%。与等容量二级 (L1/L2) SRAM 缓存替代品相比，FusedCache 提供相似的性能，但缓存能耗大幅降低 69%。与 TapeCache L1 方案相比，FusedCache 的性能提高了 7%，缓存能源节省了 6%，这意味着能源延迟乘积提高了 13%。
We propose FusedCache, a two-level set-associative Racetrack memory (RM) cache design that utilizes RM's high density for providing fast uniform access at one level, and non-uniform access at the next. FusedCache is well suited for private L1/L2 caches enforcing alignment of L1 data with the RM access points with the remaining non-aligned data serving as L2. It uses traditional LRU eviction for L1 misses. Promotion and demotion between L1 and L2 are performed through shifts and, when necessary, background swap operations. These swap operations do not require physical stores or loads, making accesses both faster and more energy efficient. Further, unlike a traditional inclusive cache hierarchy, fused L1 cache lines naturally exist in L2 avoiding duplicated storage and tag structures, promotions, and evictions. L1 status on each track is strictly enforced by track LRU maintenance and background swapping. Our results demonstrate that compared to an iso-area L1 SRAM cache replacement, FusedCache improves application performance by 7 percent while reducing cache energy by 33 percent. Compared to an iso-capacity two level (L1/L2) SRAM cache replacement, FusedCache provides similar performance with a dramatic 69 percent cache energy reduction. Compared to a TapeCache L1 scheme, FusedCache gains a 7 percent performance improvement with a 6 percent cache energy saving which translates to a 13 percent improvement in energy-delay product.