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<?xml version="1.0" encoding="gb2312"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312"/><title>linux for ppc chapter 15 jacobw </title></head><body><center><h1>BBS 水木清華站∶精華區(qū)</h1></center><a name="top"></a>發(fā)信人: plato (純真年代), 信區(qū): Embedded <br />標 題: linux for ppc chapter 15 <br />發(fā)信站: BBS 水木清華站 (Wed May 30 23:21:04 2001) <br /> <br />Next Previous Contents <br />---------------------------------------------------------------------------- <br />---- <br />15. Real Time Response <br />Check out MontaVista's Linux Real-Time characterisation projects at <a href="http://w">http://w</a> <br />ww.mvista.com/realtime <br />15.1 Soft <br />For many applications a soft real time user space thread is adequate, partic <br />ularly if you minimise kernel scheduling latency with the patches at: http:/ <br />/www.redhat.com/~mingo/lowlatency-patches/ <br />Also, see: <a href="http://lists.linuxppc.org/listarcs/linuxppc-embedded/199912/msg00">http://lists.linuxppc.org/listarcs/linuxppc-embedded/199912/msg00</a> <br />006.html <br />15.2 Hard <br />If your application requires a hard real time response with guaranteed low l <br />atency, you may need to encapsulate the real time aspects in a device driver <br />. This is how devices which have real time constraints such as serial ports <br />and disk drives are traditionally handled under most non-realtime operating <br />systems, including Linux. <br />Interrupt Latency <br />The real-time response of a driver will still be affected by other kernel co <br />de which may disable interrupts for unknown periods, increasing effective in <br />terrupt latency. For some tools to help measure interrupt latency, see: http <br />∶<i>//www.drfruitcake.com/linux/irq_blk.html </i><br />RTLinux - Real Time Linux <br /><a href="http://www.rtlinux.com/">http://www.rtlinux.com/</a> <br />If you need better latency guarantees than offerred by the kernel, use Real <br />Time Linux to decouple the hard real time portion from the rest of your appl <br />ication. v3.0 includes support for PowerPC. <br />Also, search for RTLinux. <br />RTAI - Real Time Application Interface <br /><a href="http://www.aero.polimi.it/projects/rtai/">http://www.aero.polimi.it/projects/rtai/</a> <br />The Real Time Application Interface is a kernel module which uses a hardware <br /> abstraction layer to add typical features from an industrial real time oper <br />ating system to Linux. It consists basically of an interrupt dispatcher and <br />mainly traps the peripherals interrupts and if necessary re-routes them to L <br />inux. <br />RTAI is supported on a number of MPC8xx systems by people like Denx. <br />---------------------------------------------------------------------------- <br />---- <br />Next Previous Contents <br /> <br />-- <br /> <br />※ 來源:·BBS 水木清華站 smth.org·[FROM: 166.111.161.8] <br /><a href="00000015.htm">上一篇</a><a href="javascript:history.go(-1)">返回上一頁</a><a href="index.htm">回到目錄</a><a href="#top">回到頁首</a><a href="00000017.htm">下一篇</a></h1></center><center><h1>BBS 水木清華站∶精華區(qū)</h1></center></body></html>?? 快捷鍵說明
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