Reducing Task Completion Time in Mobile Offloading Systems through Online Adaptive Local Restart
Reducing Task Completion Time in Mobile Offloading Systems through Online Adaptive Local Restart
复制标题
DOI：
10.1145/2668930.2688041
复制
发表时间：
2015-01
期刊：
影响因子：
--
通讯作者：
Qiushi Wang;K. Wolter
中科院分区：
文献类型：
--
作者：
Qiushi Wang;K. Wolter
卸载是一种提高移动设备性能的先进技术。在移动卸载系统中，繁重的计算通过无线网络连接从资源有限的移动设备迁移到强大的云服务器。不可靠的无线网络常常会干扰系统的运行。任务完成可能会因网络拥塞或数据包丢失而延迟或中断。为了解决这个问题，可以在移动设备本身本地重新启动并完成卸载的作业。在本文中，我们提出了一种动态方案来确定是否以及何时在本地重新启动任务。首先，我们设计了一个实验来探讨不可靠网络中的数据包丢失和延迟对卸载任务完成时间的影响。然后，我们从数学上推导出本地重启的先决条件和最佳超时的选择。分析结果证实，当任务完成时间的分布具有较高方差时，本地重启是有益的。此外，针对移动应用提出了动态本地重启方案。该方案跟踪任务完成时间分布的概率密度函数的方差。这是使用动态直方图完成的，动态直方图在运行时收集和更新数据。实验结果证实了本地重启方案的有效性。实验表明，在适当的时间进行本地重启比始终卸载具有更好的性能。
Offloading is an advanced technique to improve the performance of mobile devices. In a mobile offloading system, heavy computations are migrated from resource constrained mobile devices to powerful cloud servers through a wireless network connection. The unreliable wireless network often disturbs system operation. Task completion can be delayed or interrupted by congestion or packet loss in the network. To deal with this problem the offloaded jobs can be locally restarted and completed in the mobile device itself. In this paper, we propose a dynamic scheme to determine whether and when to locally restart a task. First, we design an experiment to explore the impact of packet loss and delay in unreliable networks on the completion time of an offloading task. Then, we mathematically derive the prerequisites for local restart and selection of the optimal timeout. The analysis result confirms that local restart is beneficial when the distribution of task completion time has high variance. Further, a dynamic local restart scheme is proposed for mobile applications. This scheme keeps track of the variance of the probability density function of the distribution of task completion time. This is done using a dynamic histogram, which collects and updates data at run time. The efficiency of the local restart scheme is confirmed by experimental results. The experiment shows that local restart at the right time achieves better performance than always offloading.