1. NVMeDirect: A User-Space I/O Framework for Application-specific Optimization on NVMe SSD
Ping-Sung Yeh,
Te-Hao Hsu
Conclusions
Results
Introduction
Impact of the Polling Period
Differentiated I/O Service
The new emerging technologies are making a remarkable progress in the performance of storage devices. NAND flash-based Solid State Drives (SSDs) are being widely adopted on behalf of hard disk drives (HDDs). The nextgeneration non-volatile memory such as 3D XPoint promises the next step for the storage devices. In accordance with the improvement in the storage performance, the new NVMe (Non-Volatile Memory Express) interface has been standardized to support high performance storage based on the PCI Express (PCIe) interconnect.
NVMeDirect supports prioritized I/O without H/W features
Prioritized I/O without a weighted round-robin scheduler
Using flexible binding between Handles and Queues
Sharing a single Queue with multiple Handles
Evaluation
Polling is not efficient on bandwidth sensitive workload due to th significant invrease int the CPU load
Significant performance degradation occurs in a certain polling period
Implementation on the Linux kernel 4.3.3
Experimental setop
Ubuntu LTS
3.3GHz Intel Core i7 CPU(6 cores) & 64GB of DRAM
Intel 750 Series 400GB NVMe SSD
Compariosn with
Kernel I/O
SPDK
NVMeDirect
Differentiated I/O Service
One prioritized thread with a dedicated queue,Three threads with a shared queue
Each thread performs 4KB random write
Baseline Performance
Control Polling Period dynamically based on I/O size or hints from applications
Figure depicts the IOPS of random reads (Figure a) and random writes (Figure b) on NVMeDirect, SPDK, and Kernel I/O varying the queue depth with a single thread. When the queue depth is sufficiently large, the performance of random reads and writes meets or exceeds the performance specification of the device on both NVMeDirect, SPDK, and Kernel I/O.
Design
Latency Sensitive Application
We develop a user-space I/O framework called NVMeDirect to fully utilize the performance of NVMe SSDs while meeting the diverse requirements from user applications. The figure illustrates the overall architecture of our NVMeDirect framework.
Using workload-A in YCSB on Redis
Update-heavy workload with Zipf distribution
Asynchronous random I/O performance using FIO
NVMeDirect
First full framework for I/O in the user-space based on stock NVMe devices
Can be easily applied to many applications
Useful for emerging storage devices, e.g. 3D Xpoint ,etc
Future work
User-level file systems
Porting diverse date-intensive applications over NVMeDirect
Protecting the system from illegal access
Figure a
Figure b
Acknowledgments
We would like to thank the anonymous reviewers and our shepherd, Nisha Talagala, for their valuable comments.
This work was supported by Samsung Research Funding Center of Samsung Electronics under Project Number SRFC-TB
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Literature cited
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