From 3f8e567700ff67b3b27e8ec0b22902cb716ad79d Mon Sep 17 00:00:00 2001 From: Joel Sherrill Date: Mon, 19 Oct 1998 17:46:54 +0000 Subject: New file. --- doc/supplements/hppa1_1/time_SIMHPPA.t | 86 ++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) create mode 100644 doc/supplements/hppa1_1/time_SIMHPPA.t (limited to 'doc/supplements/hppa1_1') diff --git a/doc/supplements/hppa1_1/time_SIMHPPA.t b/doc/supplements/hppa1_1/time_SIMHPPA.t new file mode 100644 index 0000000000..82982ef21d --- /dev/null +++ b/doc/supplements/hppa1_1/time_SIMHPPA.t @@ -0,0 +1,86 @@ +@c +@c COPYRIGHT (c) 1988-1998. +@c On-Line Applications Research Corporation (OAR). +@c All rights reserved. +@c +@c $Id$ +@c + +@chapter HP-7100 Timing Data + +@section Introduction + +The timing data for the PA-RISC version of RTEMS is +provided along with the target dependent aspects concerning the +gathering of the timing data. The hardware platform used to +gather the times is described to give the reader a better +understanding of each directive time provided. Also, provided +is a description of the interrupt latency and the context +switch times as they pertain to the PA-RISC version of RTEMS. + +@section Hardware Platform + +No directive execution times are reported for the +HP-7100 because the target platform was proprietary and +executions times could not be released. + +@section Interrupt Latency + +The maximum period with traps disabled or the +processor interrupt level set to it's highest value inside RTEMS +is less than RTEMS_MAXIMUM_DISABLE_PERIOD +microseconds including the instructions which +disable and re-enable interrupts. The time required for the +HP-7100 to vector an interrupt and for the RTEMS entry overhead +before invoking the user's trap handler are a total of +RTEMS_INTR_ENTRY_RETURNS_TO_PREEMPTING_TASK +microseconds. These combine to yield a worst case interrupt +latency of less than RTEMS_MAXIMUM_DISABLE_PERIOD + +RTEMS_INTR_ENTRY_RETURNS_TO_PREEMPTING_TASK microseconds at 15 Mhz. +[NOTE: The maximum period with interrupts disabled was last +determined for Release RTEMS_RELEASE_FOR_MAXIMUM_DISABLE_PERIOD.] + +It should be noted again that the maximum period with +interrupts disabled within RTEMS for the HP-7100 is hand calculated. + +@section Context Switch + +The RTEMS processor context switch time is RTEMS_NO_FP_CONTEXTS +microsections for the HP-7100 when no floating point context +switch is saved or restored. Saving and restoring the floating +point context adds additional time to the context +switch procedure. Additional execution time is required when a +TASK_SWITCH user extension is configured. The use of the +TASK_SWITCH extension is application dependent. Thus, its +execution time is not considered part of the raw context switch +time. + +Since RTEMS was designed specifically for embedded +missile applications which are floating point intensive, the +executive is optimized to avoid unnecessarily saving and +restoring the state of the numeric coprocessor. On many +processors, the state of the numeric coprocessor is only saved +when an FLOATING_POINT task is dispatched and that task was not +the last task to utilize the coprocessor. In a system with only +one FLOATING_POINT task, the state of the numeric coprocessor +will never be saved or restored. When the first FLOATING_POINT +task is dispatched, RTEMS does not need to save the current +state of the numeric coprocessor. As discussed in the Register +Usage section, on the HP-7100 the every task is considered to be +floating point registers and , as a rsule, every context switch +involves saving and restoring the state of the floating point +unit. + +The following table summarizes the context switch +times for the HP-7100 processor: + +@example +no times are available for the HP-7100 +@end example + +@section Directive Times + +No execution times are available for the HP-7100 +because the target platform was proprietary and no timing +information could be released. + -- cgit v1.2.3