一种多核ARM平台下用户态定时器的实现  

Implementation of a User-mode Timer in Multi-core ARM Platform

作　　者：喻诗祥[1,2,3] 顾乃杰[1,2,3] 张旭[1,2,3] 曹越[1,2,3] 

机构地区：[1]中国科学技术大学计算机科学技术学院,合肥230027 [2]中国科学技术大学安徽省计算与通信软件重点实验室,合肥230027 [3]中国科学技术大学先进技术研究院,合肥230027

出　　处：《计算机工程》2015年第1期19-23,30,共6页Computer Engineering

基　　金："核高基"重大专项(2009ZX01028-002-003-005);高等学校学科创新引智计划基金资助项目(B07033)

摘　　要：在ARM平台下,系统提供的posix-timer误差较大,难以满足实时要求,而且传统的Linux用户态定时器通过系统调用及信号传递的方式向进程提供定时服务,当定时器使用规模较大时,进程会在内核态用户态间频繁切换。针对上述问题,提出并实现一种基于多核ARM平台的新型用户态定时器方案。该方案采用一种新的时间轮数据结构,通过内核态与用户态共享内存等方式向进程提供服务,避免不必要的信号传递,有效地缓解频繁状态切换问题。实验结果表明,该方案保持微秒级的定时精度,定时误差相比posix-timer明显降低。In the ARM platform,the delay of Linux＇s posix-timer is big,and can not fit the requirement of real-time system. In addition,traditional Linux user-mode timer provides service to process via system call and signal so that the process switches between kernel-mode and user-mode frequently when the scale of timer being used is very large. To solve these problems,this paper designs and implements a new user-mode timer system in multi-core ARM platform. By using a novel time wheel data structure and providing service to process via sharing memory between kernel-mode and user-mode,the new system avoids the transmission of unnecessary signal,and relives the frequent state switching effectively. Experimental results show that the new system keeps the precision of the timer in micro-second and offers much smaller delay than the posix-timer.

关 键 词：Linux用户态 定时器 多核 ARM平台 时间轮 共享内存 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]