Ticket #1171: timer.t.diff

File timer.t.diff, 1.8 KB (added by ken.peters, on Dec 3, 2006 at 1:31:13 PM)


  • user/timer.t

    RCS file: /usr1/CVS/rtems/doc/user/timer.t,v
    retrieving revision 1.17
    retrieving revision 1.18
    diff -u -r1.17 -r1.18
    33@c  On-Line Applications Research Corporation (OAR).
    44@c  All rights reserved.
    6 @c  $Id: timer.t,v 1.17 2004/05/06 19:21:50 joel Exp $
     6@c  $Id: timer.t,v 1.18 2006/09/07 18:08:25 joel Exp $
    99@chapter Timer Manager
    6060The Timer Server task is responsible for executing the timer
    6161service routines associated with all task-based timers.
    6262This task executes at a priority higher than any RTEMS application
    63 task and thus can be viewed logically as the lowest priority interrupt.
     63task, and is created non-preemptible, and thus can be viewed logically as
     64the lowest priority interrupt.
    6566By providing a mechanism where timer service routines execute
    6667in task rather than interrupt space, the application is
    7071it would be save to perform floating point operations
    7172from a task-based timer.  Most of the time, executing floating
    7273point instructions from an interrupt service routine
    73 is not considered safe.
     74is not considered safe. However, since the Timer Server task
     75is non-preemptible, only directives allowed from an ISR can be
     76called in the timer service routine.
    7578The Timer Server is designed to remain blocked until a
    7679task-based timer fires.  This reduces the execution overhead
    512515@findex rtems_timer_initiate_server
    514517rtems_status_code rtems_timer_initiate_server(
    515   unsigned32           stack_size,
     518  rtems_unsigned32     priority,
     519  rtems_unsigned32     stack_size,
    516520  rtems_attribute      attribute_set