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# ====================================================================
#
# scheduler.cdl
#
# configuration data related to the kernel schedulers
#
# ====================================================================
## ####ECOSGPLCOPYRIGHTBEGIN####
## -------------------------------------------
## This file is part of eCos, the Embedded Configurable Operating System.
## Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
##
## eCos is free software; you can redistribute it and/or modify it under
## the terms of the GNU General Public License as published by the Free
## Software Foundation; either version 2 or (at your option) any later
## version.
##
## eCos is distributed in the hope that it will be useful, but WITHOUT
## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
## for more details.
##
## You should have received a copy of the GNU General Public License
## along with eCos; if not, write to the Free Software Foundation, Inc.,
## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
##
## As a special exception, if other files instantiate templates or use
## macros or inline functions from this file, or you compile this file
## and link it with other works to produce a work based on this file,
## this file does not by itself cause the resulting work to be covered by
## the GNU General Public License. However the source code for this file
## must still be made available in accordance with section (3) of the GNU
## General Public License v2.
##
## This exception does not invalidate any other reasons why a work based
## on this file might be covered by the GNU General Public License.
## -------------------------------------------
## ####ECOSGPLCOPYRIGHTEND####
# ====================================================================
######DESCRIPTIONBEGIN####
#
# Author(s): jskov
# Original data: nickg
# Contributors:
# Date: 1999-07-05
#
#####DESCRIPTIONEND####
#
# ====================================================================
cdl_interface CYGINT_KERNEL_SCHEDULER {
display "Number of schedulers in this configuration"
no_define
requires 1 == CYGINT_KERNEL_SCHEDULER
}
cdl_interface CYGINT_KERNEL_SCHEDULER_UNIQUE_PRIORITIES {
display "Non-zero if the active schedule only has unique priorities"
description "
Not all schedulers allow mutiple threads to use the same
priority. That property is signalled via this option, allowing
scheduler and tests to behave accordingly."
}
# FIXME: The two below options must be mutually exclusive
cdl_component CYGSEM_KERNEL_SCHED_MLQUEUE {
display "Multi-level queue scheduler"
default_value 1
implements CYGINT_KERNEL_SCHEDULER
description "
The multi-level queue scheduler supports multiple priority
levels and multiple threads at each priority level.
Preemption between priority levels is automatic. Timeslicing
within a given priority level is controlled by a separate
configuration option."
cdl_option CYGDBG_KERNEL_TRACE_TIMESLICE {
display "Output timeslices when tracing"
active_if CYGDBG_USE_TRACING
requires !CYGDBG_INFRA_DEBUG_TRACE_ASSERT_SIMPLE
requires !CYGDBG_INFRA_DEBUG_TRACE_ASSERT_FANCY
default_value 0
description "
When tracing is enabled, output trace messages every
timeslice. This can be quite verbose so is disabled by
default."
}
}
cdl_option CYGSEM_KERNEL_SCHED_BITMAP {
display "Bitmap scheduler"
default_value 0
implements CYGINT_KERNEL_SCHEDULER
implements CYGINT_KERNEL_SCHEDULER_UNIQUE_PRIORITIES
requires !CYGPKG_KERNEL_SMP_SUPPORT
description "
The bitmap scheduler supports multiple priority levels but
only one thread can exist at each priority level. This means
that scheduling decisions are very simple and hence the
scheduler is efficient. Preemption between priority levels is
automatic. Timeslicing within a given priority level is
irrelevant since there can be only one thread at each
priority level."
}
#cdl_option CYGSEM_KERNEL_SCHED_LOTTERY {
# display "Lottery scheduler"
# type radio
# description "
# This scheduler is not yet available."
#}
cdl_option CYGPRI_KERNEL_SCHED_IMPL_HXX {
display "Scheduler header file"
flavor data
description "
This option sets a preprocessor symbol which names the header
file for the selected scheduler. It is used internally by the
common scheduler code to include the correct header file."
calculated { \
CYGSEM_KERNEL_SCHED_BITMAP ? "<cyg/kernel/bitmap.hxx>" :\
CYGSEM_KERNEL_SCHED_MLQUEUE ? "<cyg/kernel/mlqueue.hxx>" :\
CYGSEM_KERNEL_SCHED_LOTTERY ? "<cyg/kernel/lottery.hxx>" :\
"!!!-- Configuration broken - no scheduler selected --!!!"}
}
# NOTE: This option only makes sense if the current scheduler
# supports multiple priority levels.
cdl_component CYGNUM_KERNEL_SCHED_PRIORITIES {
display "Number of priority levels"
flavor data
legal_values 1 to 32
default_value 32
#active_if CYGINT_KERNEL_SCHED_PRIORITY_SCHEDULER
description "
This option controls the number of priority levels that are
available. For some types of scheduler including the bitmap
scheduler this may impose an upper bound on the number of
threads in the system. For other schedulers such as the
mlqueue scheduler the number of threads is independent from
the number of priority levels. Note that the lowest priority
level is normally used only by the idle thread, although
application threads can run at this priority if necessary."
cdl_option CYGNUM_KERNEL_SCHED_BITMAP_SIZE {
display "Bitmap size"
flavor data
calculated {"CYGNUM_KERNEL_SCHED_PRIORITIES"}
description "
This option automatically defines the size of bitmap
used to track occupied priority levels."
}
cdl_option CYGIMP_KERNEL_SCHED_SORTED_QUEUES {
display "Dequeue highest priority threads first"
flavor bool
default_value 0
description "
With this option enabled, threads queued in a thread queue
will be dequeued in priority order, rather than first in,
first out (FIFO). Threads of equal priority are dequeued
oldest first. The only exception is the scheduler run
queues where order is less important as each is already
sorted by priority. Note that this makes the thread queueing
less deterministic."
}
}
# ---------------------------------------------------------------------
# Timeslice options
# NOTE: this option only makes sense for some of the schedulers.
# Timeslicing is irrelevant for bitmap schedulers.
cdl_component CYGSEM_KERNEL_SCHED_TIMESLICE {
display "Scheduler timeslicing"
requires !CYGSEM_KERNEL_SCHED_BITMAP
requires CYGVAR_KERNEL_COUNTERS_CLOCK
default_value 1
description "
Some schedulers including the mlqueue scheduler support
timeslicing. This means that the kernel will check regularly
whether or not there is another runnable thread with the
same priority, and if there is such a thread there will be
an automatic context switch. Not all applications require
timeslicing, for example because every thread performs a
blocking operation regularly. For these applications it is
possible to disable timeslicing, which reduces the overheads
associated with timer interrupts."
cdl_option CYGNUM_KERNEL_SCHED_TIMESLICE_TICKS {
display "Number of clock ticks between timeslices"
flavor data
legal_values 1 to 65535
default_value 5
description "
Assuming timeslicing is enabled, how frequently should it
take place? The value of this option corresponds to the
number of clock ticks that should occur before a timeslice
takes place, so increasing the value reduces the frequency
of timeslices."
}
cdl_option CYGSEM_KERNEL_SCHED_TIMESLICE_ENABLE {
display "Support runtime enable of timeslice per-thread"
flavor bool
default_value false
description "This option makes timslicing a per-thread runtime
option. When enabled, threads may have timeslicing
turned on or off dynamically. This is generally used
by higher level APIs (such as POSIX) to implement
differing scheduling policies."
}
}
# ---------------------------------------------------------------------
# ASR support options
cdl_component CYGSEM_KERNEL_SCHED_ASR_SUPPORT {
display "Enable ASR support"
flavor bool
default_value false
description "
This component controls support for Asynchronous Service
Routines (ASRs). This is a function that may be called
from the scheduler when it has just exited the scheduler
lock. This is primarily for use by API compatibility layers."
cdl_option CYGSEM_KERNEL_SCHED_ASR_GLOBAL {
display "Make ASR function global"
flavor bool
default_value true
description "
This option controls whether the ASR function is shared by
all threads, or whether each thread may have its own ASR
function."
}
cdl_option CYGSEM_KERNEL_SCHED_ASR_DATA_GLOBAL {
display "Make ASR data global"
flavor bool
default_value true
description "
This option controls whether the ASR data is shared by
all threads, or whether each thread may have its own ASR
data. This is independent of the previous option because
it may be useful to pass per-thread data to a shared ASR
function."
}
}
# EOF scheduler.cdl
|
