# ==================================================================== # # 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 Red Hat, 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., ## 59 Temple Place, Suite 330, Boston, MA 02111-1307 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. ## ## This exception does not invalidate any other reasons why a work based on ## this file might be covered by the GNU General Public License. ## ## Alternative licenses for eCos may be arranged by contacting Red Hat, Inc. ## at http://sources.redhat.com/ecos/ecos-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 ? "" :\ CYGSEM_KERNEL_SCHED_MLQUEUE ? "" :\ CYGSEM_KERNEL_SCHED_LOTTERY ? "" :\ "!!!-- 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