最优线程数设置是影响多线程程序性能和功耗的关键之一。然而,目前寻找最优线程数的算法通常是从单一固定起点开始搜索,往往会造成搜索精度低、搜索开销大的问题。最优线程数的分布和位置与多种因素有关,包括程序所属类型、优化目标(性...最优线程数设置是影响多线程程序性能和功耗的关键之一。然而,目前寻找最优线程数的算法通常是从单一固定起点开始搜索,往往会造成搜索精度低、搜索开销大的问题。最优线程数的分布和位置与多种因素有关,包括程序所属类型、优化目标(性能、功耗和EDP(Energy-delay Product))、并行的多线程区域、软硬件配置参数等。围绕能效优先的最优线程数搜索问题,提出了能效优先的特定起点分类最优线程数搜索算法(Energy-Efficiency-First Optimal Thread Number Search Algorithm based on Specific Starting Point Classification,简称TS^(3)方法)”,通过设计基于程序分类的特殊起点设定方法来确定搜索起点,并采用启发式算法和二分查找方法搜索最优线程数,提升搜索效率,有效提升了能效优先目标(性能最优、功耗最优、能效EDP最优)下的最优线程数搜索精度并降低了搜索开销。在两个x86和一个ARM平台上用8个benchmark对算法有效性进行了详细实验验证,结果表明,与Baseline相比,TS^(3)方法的性能平均提升0.29%(平台A)、0.17%(平台B)、10.77%(平台C);功耗平均降低2.35%(平台A)、1.87%(平台B)、15.97%(平台C);EDP平均降低6.36%(平台A)、5.07%(平台B)、46.94%(平台C)。在3个平台上,与目前经典搜索方法相比,TS^(3)方法的性能平均提升10.16%,功耗平均降低13.45%,EDP平均降低23.77%;搜索开销平均降低86.8%。展开更多
Worst-case execution time (WCET) analysis of multi-threaded software is still a challenge. This comes mainly from the fact that synchronization has to be taken into account. In this paper, we focus on this issue and o...Worst-case execution time (WCET) analysis of multi-threaded software is still a challenge. This comes mainly from the fact that synchronization has to be taken into account. In this paper, we focus on this issue and on automatically calculating and incorporating stalling times (e.g. caused by lock contention) in a generic graph model. The idea that thread interleavings can be studied with a matrix calculus is novel in this research area. Our sparse matrix representations of the program are manipulated using an extended Kronecker algebra. The resulting graph represents multi-threaded programs similar as CFGs do for sequential programs. With this graph model, we are able to calculate the WCET of multi-threaded concurrent programs including stalling times which are due to synchronization. We employ a generating function-based approach for setting up data flow equations which are solved by well-known elimination-based dataflow analysis methods or an off-the-shelf equation solver. The WCET of multi-threaded programs can finally be calculated with a non-linear function solver.展开更多
文摘最优线程数设置是影响多线程程序性能和功耗的关键之一。然而,目前寻找最优线程数的算法通常是从单一固定起点开始搜索,往往会造成搜索精度低、搜索开销大的问题。最优线程数的分布和位置与多种因素有关,包括程序所属类型、优化目标(性能、功耗和EDP(Energy-delay Product))、并行的多线程区域、软硬件配置参数等。围绕能效优先的最优线程数搜索问题,提出了能效优先的特定起点分类最优线程数搜索算法(Energy-Efficiency-First Optimal Thread Number Search Algorithm based on Specific Starting Point Classification,简称TS^(3)方法)”,通过设计基于程序分类的特殊起点设定方法来确定搜索起点,并采用启发式算法和二分查找方法搜索最优线程数,提升搜索效率,有效提升了能效优先目标(性能最优、功耗最优、能效EDP最优)下的最优线程数搜索精度并降低了搜索开销。在两个x86和一个ARM平台上用8个benchmark对算法有效性进行了详细实验验证,结果表明,与Baseline相比,TS^(3)方法的性能平均提升0.29%(平台A)、0.17%(平台B)、10.77%(平台C);功耗平均降低2.35%(平台A)、1.87%(平台B)、15.97%(平台C);EDP平均降低6.36%(平台A)、5.07%(平台B)、46.94%(平台C)。在3个平台上,与目前经典搜索方法相比,TS^(3)方法的性能平均提升10.16%,功耗平均降低13.45%,EDP平均降低23.77%;搜索开销平均降低86.8%。
文摘Worst-case execution time (WCET) analysis of multi-threaded software is still a challenge. This comes mainly from the fact that synchronization has to be taken into account. In this paper, we focus on this issue and on automatically calculating and incorporating stalling times (e.g. caused by lock contention) in a generic graph model. The idea that thread interleavings can be studied with a matrix calculus is novel in this research area. Our sparse matrix representations of the program are manipulated using an extended Kronecker algebra. The resulting graph represents multi-threaded programs similar as CFGs do for sequential programs. With this graph model, we are able to calculate the WCET of multi-threaded concurrent programs including stalling times which are due to synchronization. We employ a generating function-based approach for setting up data flow equations which are solved by well-known elimination-based dataflow analysis methods or an off-the-shelf equation solver. The WCET of multi-threaded programs can finally be calculated with a non-linear function solver.
