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authorJoel Sherrill <joel.sherrill@OARcorp.com>1998-08-13 21:17:35 +0000
committerJoel Sherrill <joel.sherrill@OARcorp.com>1998-08-13 21:17:35 +0000
commitabb3c7557ef70796d6de1dac47b6f9a120103506 (patch)
tree9b9ff6a7ca56a0b4393b697a532f143434a2777d /doc/supplements/powerpc/timeDMV177.t
parentAdded text to clarify the queueing of multiple events. (diff)
downloadrtems-abb3c7557ef70796d6de1dac47b6f9a120103506.tar.bz2
Added DMV177 times files and made this all regenerate with two timing
chapters.
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+@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
+
+@ifinfo
+@node DMV177 Timing Data, DMV177 Timing Data Introduction, PSIM Timing Data Rate Monotonic Manager, Top
+@end ifinfo
+@chapter DMV177 Timing Data
+@ifinfo
+@menu
+* DMV177 Timing Data Introduction::
+* DMV177 Timing Data Hardware Platform::
+* DMV177 Timing Data Interrupt Latency::
+* DMV177 Timing Data Context Switch::
+* DMV177 Timing Data Directive Times::
+* DMV177 Timing Data Task Manager::
+* DMV177 Timing Data Interrupt Manager::
+* DMV177 Timing Data Clock Manager::
+* DMV177 Timing Data Timer Manager::
+* DMV177 Timing Data Semaphore Manager::
+* DMV177 Timing Data Message Manager::
+* DMV177 Timing Data Event Manager::
+* DMV177 Timing Data Signal Manager::
+* DMV177 Timing Data Partition Manager::
+* DMV177 Timing Data Region Manager::
+* DMV177 Timing Data Dual-Ported Memory Manager::
+* DMV177 Timing Data I/O Manager::
+* DMV177 Timing Data Rate Monotonic Manager::
+@end menu
+@end ifinfo
+
+@ifinfo
+@node DMV177 Timing Data Introduction, DMV177 Timing Data Hardware Platform, DMV177 Timing Data, DMV177 Timing Data
+@end ifinfo
+@section Introduction
+
+The timing data for RTEMS on the DMV177 implementation
+of the PowerPC architecture 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
+PowerPC version of RTEMS.
+
+@ifinfo
+@node DMV177 Timing Data Hardware Platform, DMV177 Timing Data Interrupt Latency, DMV177 Timing Data Introduction, DMV177 Timing Data
+@end ifinfo
+@section Hardware Platform
+
+All times reported in this chapter were measured using the PowerPC
+Instruction Simulator (PSIM). PSIM simulates a variety of PowerPC
+6xx models with the DMV177 being used as the basis for the measurements
+reported in this chapter.
+
+The PowerPC decrementer register was was used to gather
+all timing information. In real hardware implementations
+of the PowerPC architecture, this register would typically
+count something like CPU cycles or be a function of the clock
+speed. However, wth PSIM each count of the decrementer register
+represents an instruction. Thus all measurements in this
+chapter are reported as the actual number of instructions
+executed. All sources of hardware interrupts were disabled,
+although traps were enabled and the interrupt level of the
+PowerPC allows all interrupts.
+
+@ifinfo
+@node DMV177 Timing Data Interrupt Latency, DMV177 Timing Data Context Switch, DMV177 Timing Data Hardware Platform, DMV177 Timing Data
+@end ifinfo
+@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
+PowerPC 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
+RTEMS_MAXIMUM_DISABLE_PERIOD_MHZ Mhz.
+[NOTE: The maximum period with interrupts disabled was last
+determined for Release RTEMS_RELEASE_FOR_MAXIMUM_DISABLE_PERIOD.]
+
+The maximum period with interrupts disabled within
+RTEMS is hand-timed with some assistance from PSIM. The maximum
+period with interrupts disabled with RTEMS occurs .... XXX
+
+The interrupt vector and entry overhead time was
+generated on the PSIM benchmark platform using the PowerPC's
+decrementer register. This register was programmed to generate
+an interrupt after one countdown.
+
+@ifinfo
+@node DMV177 Timing Data Context Switch, DMV177 Timing Data Directive Times, DMV177 Timing Data Interrupt Latency, DMV177 Timing Data
+@end ifinfo
+@section Context Switch
+
+The RTEMS processor context switch time is XXX
+microseconds on the PSIM 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 following table summarizes the context switch
+times for the PSIM benchmark platform:
+
+@include timetbldmv177.texi
+
+@tex
+\global\advance \smallskipamount by 4pt
+@end tex
+
+