Revamping Storage Class Memory With Hardware Automated Memory-Over-Storage Solution
Revamping Storage Class Memory With Hardware Automated Memory-Over-Storage Solution
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DOI：
10.1109/isca52012.2021.00065
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发表时间：
2021-06
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影响因子：
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通讯作者：
Jie Zhang;Miryeong Kwon;Donghyun Gouk;Sungjoon Koh;N. Kim;M. Kandemir;Myoungsoo Jung
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文献类型：
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作者：
Jie Zhang;Miryeong Kwon;Donghyun Gouk;Sungjoon Koh;N. Kim;M. Kandemir;Myoungsoo Jung
NVDIMM 等大型持久内存被认为是一种颠覆性内存技术，因为它们即使在断电后也能保持系统状态，并允许系统快速恢复。然而，大量软件堆栈干预所产生的开销严重抵消了此类存储器的优势。首先，为了显着减少软件堆栈开销，我们提出了 HAMS，一种硬件自动内存存储 (MoS) 解决方案。具体来说，HAMS将NVDIMM和超低延迟闪存存档（ULL-Flash）的容量聚合到单个大内存空间中，该空间可以以操作系统透明的方式用作工作内存扩展或持久内存扩展。 HAMS驻留在内存控制器集线器中，并通过传统的DDR和NVMe接口管理其MoS地址池；在将 ULL-Flash 的存储空间映射到 NVDIMM 的内存空间后，它采用简单的硬件缓存来服务主机 MMU 的所有内存请求。其次，为了使HAMS更加节能和可靠，我们提出了一种“高级HAMS”，在优化HAMS的数据路径和硬件模块后，消除了NVDIMM和ULL-Flash之间不必要的数据传输。这种方法将 ULL-Flash 及其 NVMe 控制器从存储盒中释放出来，并通过传统 DDR4 接口将 HAMS 数据路径直接连接到 NVDIMM。我们的评估表明，HAMS 和高级 HAMS 的系统性能比基于软件的 NVDIMM 设计高出 97% 和 119%，同时能耗分别降低 41% 和 45%。
Large persistent memories such as NVDIMM have been perceived as a disruptive memory technology, because they can maintain the state of a system even after a power failure and allow the system to recover quickly. However, overheads incurred by a heavy software-stack intervention seriously negate the benefits of such memories. First, to significantly reduce the software stack overheads, we propose HAMS, a hardware auto-mated Memory-over-Storage (MoS) solution. Specifically, HAMS aggregates the capacity of NVDIMM and ultra-low latency flash archives (ULL-Flash) into a single large memory space, which can be used as a working memory expansion or persistent memory expansion, in an OS-transparent manner. HAMS resides in the memory controller hub and manages its MoS address pool over conventional DDR and NVMe interfaces; it employs a simple hardware cache to serve all the memory requests from the host MMU after mapping the storage space of ULL-Flash to the memory space of NVDIMM. Second, to make HAMS more energy-efficient and reliable, we propose an "advanced HAMS" which removes unnecessary data transfers between NVDIMM and ULL-Flash after optimizing the datapath and hardware modules of HAMS. This approach unleashes the ULL-Flash and its NVMe controller from the storage box and directly connects the HAMS datapath to NVDIMM over the conventional DDR4 interface. Our evaluations show that HAMS and advanced HAMS can offer 97% and 119% higher system performance than a software-based NVDIMM design, while costing 41% and 45% lower energy, respectively.