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diff --git a/doc/supplements/m68k/timeMVME136.t b/doc/supplements/m68k/timeMVME136.t deleted file mode 100644 index 7f126b4606..0000000000 --- a/doc/supplements/m68k/timeMVME136.t +++ /dev/null @@ -1,108 +0,0 @@ -@c -@c COPYRIGHT (c) 1988-1998. -@c On-Line Applications Research Corporation (OAR). -@c All rights reserved. -@c -@c $Id$ -@c - -@include ../../common/timemac.texi -@tex -\global\advance \smallskipamount by -4pt -@end tex - -@chapter MVME136 Timing Data - -@section Introduction - -The timing data for the MC68020 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 MC68020 version of RTEMS. - -@section Hardware Platform - -All times reported except for the maximum period -interrupts are disabled by RTEMS were measured using a Motorola -MVME135 CPU board. The MVME135 is a 20Mhz board with one wait -state dynamic memory and a MC68881 numeric coprocessor. The -Zilog 8036 countdown timer on this board was used to measure -elapsed time with a one-half microsecond resolution. All -sources of hardware interrupts were disabled, although the -interrupt level of the MC68020 allows all interrupts. - -The maximum period interrupts are disabled was -measured by summing the number of CPU cycles required by each -assembly language instruction executed while interrupts were -disabled. The worst case times of the MC68020 microprocessor -were used for each instruction. Zero wait state memory was -assumed. The total CPU cycles executed with interrupts -disabled, including the instructions to disable and enable -interrupts, was divided by 20 to simulate a 20Mhz MC68020. It -should be noted that the worst case instruction times for the -MC68020 assume that the internal cache is disabled and that no -instructions overlap. - -@section Interrupt Latency - -The maximum period with interrupts disabled within -RTEMS is less than RTEMS_MAXIMUM_DISABLE_PERIOD -microseconds including the instructions -which disable and re-enable interrupts. The time required for -the MC68020 to vector an interrupt and for the RTEMS entry -overhead before invoking the user's interrupt 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 20Mhz. [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 is hand-timed and based upon -worst case (i.e. CPU cache disabled and no instruction overlap) -times for a 20Mhz MC68020. The interrupt vector and entry -overhead time was generated on an MVME135 benchmark platform -using the Multiprocessing Communications registers to generate -as the interrupt source. - -@section Context Switch - -The RTEMS processor context switch time is RTEMS_NO_FP_CONTEXTS -microseconds on the MVME135 benchmark platform when no floating -point context is saved or restored. 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. 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. - -The exact amount of time required to save and restore -floating point context is dependent on whether an MC68881 or -MC68882 is being used as well as the state of the numeric -coprocessor. These numeric coprocessors define three operating -states: initialized, idle, and busy. RTEMS places the -coprocessor in the initialized state when a task is started or -restarted. Once the task has utilized the coprocessor, it is in -the idle state when floating point instructions are not -executing and the busy state when floating point instructions -are executing. The state of the coprocessor is task specific. - -The following table summarizes the context switch -times for the MVME135 benchmark platform: - |