一种粗粒度可重构体系结构多目标优化映射算法

针对多约束下的行流水粗粒度可重构体系结构的硬件任务划分映射问题,提出了一种多目标优化映射算法.该算法根据运算节点执行时延、依赖度等因素构造了累加概率权值函数,在满足可重构单元面积和互连等约束下,通过该函数值动态调整就绪节点的映射调度次序,当一块可重构单元阵列当前行映射完毕后,就自动换行,当一块阵列被填满,就切换到下一块,当一个数据流图映射完毕后,就自动计算划分块数等参数.实验结果表明,与层贪婪映射算法相比,文中算法平均执行总周期降低了8.4%(RCA_4×4)和5.3%(RCA_6×6),与分裂压缩内核映射算法相比,文中算法平均执行总周期降低了20.6%(RCA_4×4)和21.0%(RCA_6×6),从而验证了文中提出算法的有效性.     

基于噪声子空间映射的二维波达角快速估计算法

为了降低二维MUSIC(Two Dimensional Multiple Signal Classification,2-D MUSIC)算法的计算量,提高算法的实时处理能力,基于噪声子空间映射思想提出了一种适用于任意平面阵列结构的二维波达角(Direction Of Arrival,DOA)快速估计算法.新算法利用空间角度划分及非线性变换将信号子空间与噪声子空间的正交性等价地压缩至某个角度分片内,使得真实DOA在该角度分片内产生虚拟镜像,通过搜索该角度分片得到虚拟DOA,最后利用数学式直接计算得到真实DOA.理论分析和实验结果表明新算法能够成倍地提高DOA估计的速度,同时具有比MUSIC算法更高的空间分辨率.     

Efficient algorithms for scheduling multiple bulk data transfers in inter‐datacenter networks

Bulk data transfers, such as backups and propagation of bulky updates, account for a large portion of the inter‐datacenter traffic. These bulk transfers consume massive bandwidth and further increase the operational cost of datacenters. The advent of store‐and‐forward transfer mode offers the opportunity for cloud provider companies to transfer bulk data by utilizing dynamic leftover bandwidth resources. In this paper, we study the multiple bulk data transfers scheduling problem in inter‐datacenter networks with dynamic link capacities. To improve the network utilization while guaranteeing fairness among requests, we employ the max–min fairness and aim at computing the lexicographically maximized solution. Leveraging the time‐expanded technique, the problem in dynamic networks is formulated as a static multi‐flow model. Then, we devise an optimal algorithm to solve it simultaneously from routing assignments and bandwidth allocation. To further reduce the computational cost, we propose to select an appropriate number of disjoint paths for each request. Extensive simulations are conducted on a real datacenter topology and prove that (i) benefiting from max–min fairness, the network utilization is significantly improved while honoring each individual performance; (ii) a small number of disjoint paths per request are sufficient to obtain the near optimal allocation within practical execution time. Copyright © 2013 John Wiley & Sons, Ltd.