SmartCon: Smart Context Switching for Fast Storage Devices

Title
SmartCon: Smart Context Switching for Fast Storage Devices
Author
원유집
Keywords
Design; Algorithms; Performance; Nonvolatile memory; solid state disk; context switch; I/O subsystem
Issue Date
2015-03
Publisher
ASSOC COMPUTING MACHINERY
Citation
ACM TRANSACTIONS ON STORAGE, v. 11, NO 2, Page. 1-25
Abstract
Handling of storage IO in modern operating systems assumes that such devices are slow and CPU cycles are valuable. Consequently, to effectively exploit the underlying hardware resources, for example, CPU cycles, storage bandwidth and the like, whenever an IO request is issued to such device, the requesting thread is switched out in favor of another thread that may be ready to execute. Recent advances in nonvolatile storage technologies and multicore CPUs make both of these assumptions increasingly questionable, and an unconditional context switch is no longer desirable. In this article, we propose a novel mechanism called SmartCon, which intelligently decides whether to service a given IO request in interrupt-driven manner or busy-wait-based manner based on not only the device characteristics but also dynamic parameters such as IO latency, CPU utilization, and IO size. We develop an analytic performance model to project the performance of SmartCon for forthcoming devices. We implement SmartCon mechanism on Linux 2.6 and perform detailed evaluation using three different IO devices: Ramdisk, low-end SSD, and high-end SSD. We find that SmartCon yields up to a 39% performance gain over the mainstream block device approach for Ramdisk, and up to a 45% gain for PCIe-based SSD and SATA-based SSDs. We examine the detailed behavior of TLB, L1, L2 cache and show that SmartCon achieves significant improvement in all cache misbehaviors.
URI
http://dl.acm.org/citation.cfm?id=2631922http://hdl.handle.net/20.500.11754/23298
ISSN
1553-3077; 1553-3093
DOI
10.1145/2631922
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > COMPUTER SCIENCE AND ENGINEERING(컴퓨터공학부) > Articles
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