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NVMe &Modern PC and CPU Ar-chitecture

Typical PC Layout (Intel) Northbridge

◦ Memory controller hub◦ Obsolete in Sandy Bridge

Southbridge◦ I/O controller hub◦ Platform Controller Hub (PCH)

in Intel Core i series

DMI (Direct Media Interface)◦ Intel’s proprietary link between

northbridge and southbridge◦ Shares many characteristics with PCIe

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AHCI (Advanced Host Controller Inter-face)

Adaptor-to-host side interface (HBA)◦ AHCI supports

◦ Advanced features of SATA (adaptor-to-device side interface)◦ System interconnect (host bus) PCI/PCIe

◦ Logical translation between two sides

Features◦ Queuing interface◦ Power management

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NVMe (Non-Volatile Memory Ex-press)

Background◦ Introduction of SSD

◦ Performance capabilities are orders of magnitude greater than previous storage devices

NVMe◦ Device interface

◦ Attach directly to the PCIe bus

◦ Feature◦ Highly parallel and highly scalable◦ Namespace

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NVMe Latency NVMe reduces latency overhead by more than 50%

◦ SCSI/SAS: 6.0 µs 19,500 cycles◦ NVMe: 2.8 µs 9,100 cycles

Credit : Slide from Flash Memory Summit 2013 5/12

Namespace Namespace

Partitioning of the physical storage extent into multiple logical storage extents

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NVMe Subsystem Multi-Path I/O and Namespace Sharing

◦ One or more controller◦ One or more namespaces◦ One or more PCI Express ports◦ A NV memory storage medium

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PCIe SR-IOV

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PCIe Multi-Path Usage Model

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PCIe External Cabling ePCIe (external PCI express, Cabled PCI express)

◦ Specifications released by PCI-SGI in Feb., 2007

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Intel Processor Architecture Core i series

◦ Nehalem◦ FSB -> QPI ◦ Southbridge -> PCH (Lynnfield)

◦ Sandy Bridge◦ Northbridge disappeared

◦ Ivy Bridge◦ 22nm die

◦ Haswell◦ Transactional Synchronization Extensions (TSX)

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Modern PC Layout & NVMe Sandy Bridge & NVMe

◦ PCIe is directly connected to CPU◦ NVMe is able to maximize storage performance

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References A Comparison of NVMe and AHCI, 2012

NVM Express: Unlock Your Solid State Drives Potential, Flash Memory Summit

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