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nuttx/sched/sched/sched.h

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/****************************************************************************
* sched/sched/sched.h
*
* Copyright (C) 2007-2014, 2016, 2018 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
#ifndef __SCHED_SCHED_SCHED_H
#define __SCHED_SCHED_SCHED_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdbool.h>
#include <queue.h>
#include <sched.h>
#include <nuttx/arch.h>
#include <nuttx/kmalloc.h>
#include <nuttx/spinlock.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Although task IDs can take the (positive, non-zero)
* range of pid_t, the number of tasks that will be supported
* at any one time is (artificially) limited by the CONFIG_MAX_TASKS
* configuration setting. Limiting the number of tasks speeds certain
* OS functions (this is the only limitation in the number of
* tasks built into the design).
*/
#if CONFIG_MAX_TASKS & (CONFIG_MAX_TASKS - 1)
# error CONFIG_MAX_TASKS must be power of 2
#endif
#define MAX_TASKS_MASK (CONFIG_MAX_TASKS-1)
#define PIDHASH(pid) ((pid) & MAX_TASKS_MASK)
/* These are macros to access the current CPU and the current task on a CPU.
* These macros are intended to support a future SMP implementation.
* NOTE: this_task() for SMP is implemented in sched_thistask.c if the CPU
* supports disabling of inter-processor interrupts or if it supports the
* atomic fetch add operation.
*/
#ifdef CONFIG_SMP
# define current_task(cpu) ((FAR struct tcb_s *)g_assignedtasks[cpu].head)
# define this_cpu() up_cpu_index()
# if !defined(CONFIG_ARCH_GLOBAL_IRQDISABLE) && !defined(CONFIG_ARCH_HAVE_FETCHADD)
# define this_task() (current_task(this_cpu()))
# endif
#else
# define current_task(cpu) ((FAR struct tcb_s *)g_readytorun.head)
# define this_cpu() (0)
# define this_task() (current_task(this_cpu()))
#endif
/* This macro returns the running task which may different from this_task()
* during interrupt level context switches.
*/
#define running_task() \
(up_interrupt_context() ? g_running_tasks[this_cpu()] : this_task())
/* List attribute flags */
#define TLIST_ATTR_PRIORITIZED (1 << 0) /* Bit 0: List is prioritized */
#define TLIST_ATTR_INDEXED (1 << 1) /* Bit 1: List is indexed by CPU */
#define TLIST_ATTR_RUNNABLE (1 << 2) /* Bit 2: List includes running tasks */
#define __TLIST_ATTR(s) g_tasklisttable[s].attr
#define TLIST_ISPRIORITIZED(s) ((__TLIST_ATTR(s) & TLIST_ATTR_PRIORITIZED) != 0)
#define TLIST_ISINDEXED(s) ((__TLIST_ATTR(s) & TLIST_ATTR_INDEXED) != 0)
#define TLIST_ISRUNNABLE(s) ((__TLIST_ATTR(s) & TLIST_ATTR_RUNNABLE) != 0)
#define __TLIST_HEAD(s) (FAR dq_queue_t *)g_tasklisttable[s].list
#define __TLIST_HEADINDEXED(s,c) (&(__TLIST_HEAD(s))[c])
#ifdef CONFIG_SMP
# define TLIST_HEAD(s,c) \
((TLIST_ISINDEXED(s)) ? __TLIST_HEADINDEXED(s,c) : __TLIST_HEAD(s))
# define TLIST_BLOCKED(s) __TLIST_HEAD(s)
#else
# define TLIST_HEAD(s) __TLIST_HEAD(s)
# define TLIST_BLOCKED(s) __TLIST_HEAD(s)
#endif
/****************************************************************************
* Public Type Definitions
****************************************************************************/
/* This structure defines the format of the hash table that is used to (1)
* determine if a task ID is unique, and (2) to map a process ID to its
* corresponding TCB.
*
* NOTE also that CPU load measurement data is retained in his table vs. in
* the TCB which would seem to be the more logic place. It is place in the
* hash table, instead, to facilitate CPU load adjustments on all threads
* during timer interrupt handling. sched_foreach() could do this too, but
* this would require a little more overhead.
*/
struct pidhash_s
{
FAR struct tcb_s *tcb; /* TCB assigned to this PID */
pid_t pid; /* The full PID value */
#ifdef CONFIG_SCHED_CPULOAD
uint32_t ticks; /* Number of ticks on this thread */
#endif
};
/* This structure defines an element of the g_tasklisttable[]. This table
* is used to map a task_state enumeration to the corresponding task list.
*/
struct tasklist_s
{
DSEG volatile dq_queue_t *list; /* Pointer to the task list */
uint8_t attr; /* List attribute flags */
};
/****************************************************************************
* Public Data
****************************************************************************/
/* Declared in nx_start.c ***************************************************/
/* The state of a task is indicated both by the task_state field of the TCB
* and by a series of task lists. All of these tasks lists are declared
* below. Although it is not always necessary, most of these lists are
* prioritized so that common list handling logic can be used (only the
* g_readytorun, the g_pendingtasks, and the g_waitingforsemaphore lists
* need to be prioritized).
*/
/* This is the list of all tasks that are ready to run. This is a
* prioritized list with head of the list holding the highest priority
* (unassigned) task. In the non-SMP case, the head of this list is the
* currently active task and the tail of this list, the lowest priority
* task, is always the IDLE task.
*/
extern volatile dq_queue_t g_readytorun;
#ifdef CONFIG_SMP
/* In order to support SMP, the function of the g_readytorun list changes,
* The g_readytorun is still used but in the SMP case it will contain only:
*
* - Only tasks/threads that are eligible to run, but not currently running,
* and
* - Tasks/threads that have not been assigned to a CPU.
*
* Otherwise, the TCB will be retained in an assigned task list,
* g_assignedtasks. As its name suggests, on 'g_assignedtasks queue for CPU
* 'n' would contain only tasks/threads that are assigned to CPU 'n'. Tasks/
* threads would be assigned a particular CPU by one of two mechanisms:
*
* - (Semi-)permanently through an RTOS interfaces such as
* pthread_attr_setaffinity(), or
* - Temporarily through scheduling logic when a previously unassigned task
* is made to run.
*
* Tasks/threads that are assigned to a CPU via an interface like
* pthread_attr_setaffinity() would never go into the g_readytorun list, but
* would only go into the g_assignedtasks[n] list for the CPU 'n' to which
* the thread has been assigned. Hence, the g_readytorun list would hold
* only unassigned tasks/threads.
*
* Like the g_readytorun list in in non-SMP case, each g_assignedtask[] list
* is prioritized: The head of the list is the currently active task on this
* CPU. Tasks after the active task are ready-to-run and assigned to this
* CPU. The tail of this assigned task list, the lowest priority task, is
* always the CPU's IDLE task.
*/
extern volatile dq_queue_t g_assignedtasks[CONFIG_SMP_NCPUS];
/* g_running_tasks[] holds a references to the running task for each cpu.
* It is valid only when up_interrupt_context() returns true.
*/
extern FAR struct tcb_s *g_running_tasks[CONFIG_SMP_NCPUS];
#else
extern FAR struct tcb_s *g_running_tasks[1];
#endif
/* This is the list of all tasks that are ready-to-run, but cannot be placed
* in the g_readytorun list because: (1) They are higher priority than the
* currently active task at the head of the g_readytorun list, and (2) the
* currently active task has disabled pre-emption.
*/
extern volatile dq_queue_t g_pendingtasks;
/* This is the list of all tasks that are blocked waiting for a semaphore */
extern volatile dq_queue_t g_waitingforsemaphore;
/* This is the list of all tasks that are blocked waiting for a signal */
#ifndef CONFIG_DISABLE_SIGNALS
extern volatile dq_queue_t g_waitingforsignal;
#endif
/* This is the list of all tasks that are blocked waiting for a message
* queue to become non-empty.
*/
#ifndef CONFIG_DISABLE_MQUEUE
extern volatile dq_queue_t g_waitingformqnotempty;
#endif
/* This is the list of all tasks that are blocked waiting for a message
* queue to become non-full.
*/
#ifndef CONFIG_DISABLE_MQUEUE
extern volatile dq_queue_t g_waitingformqnotfull;
#endif
/* This is the list of all tasks that are blocking waiting for a page fill */
#ifdef CONFIG_PAGING
extern volatile dq_queue_t g_waitingforfill;
#endif
/* This the list of all tasks that have been initialized, but not yet
* activated. NOTE: This is the only list that is not prioritized.
*/
extern volatile dq_queue_t g_inactivetasks;
/* These are lists of dayed memory deallocations that need to be handled
* within the IDLE loop or worker thread. These deallocations get queued
* by sched_kufree and sched_kfree() if the OS needs to deallocate memory
* while it is within an interrupt handler.
*/
#if (defined(CONFIG_BUILD_PROTECTED) || defined(CONFIG_BUILD_KERNEL)) && \
defined(CONFIG_MM_KERNEL_HEAP)
extern volatile sq_queue_t g_delayed_kfree;
#endif
#ifndef CONFIG_BUILD_KERNEL
/* REVISIT: It is not safe to defer user allocation in the kernel mode
* build. Why? Because the correct user context will not be in place
* when these deferred de-allocations are performed. In order to make
* this work, we would need to do something like: (1) move g_delayed_kufree
* into the group structure, then traverse the groups to collect garbage on
* a group-by-group basis.
*/
extern volatile sq_queue_t g_delayed_kufree;
#endif
/* This is the value of the last process ID assigned to a task */
extern volatile pid_t g_lastpid;
/* The following hash table is used for two things:
*
* 1. This hash table greatly speeds the determination of a new unique
* process ID for a task, and
* 2. Is used to quickly map a process ID into a TCB.
*
* It has the side effects of using more memory and limiting the number
* of tasks to CONFIG_MAX_TASKS.
*/
extern struct pidhash_s g_pidhash[CONFIG_MAX_TASKS];
/* This is a table of task lists. This table is indexed by the task stat
* enumeration type (tstate_t) and provides a pointer to the associated
* static task list (if there is one) as well as a a set of attribute flags
* indicating properties of the list, for example, if the list is an
* ordered list or not.
*/
extern const struct tasklist_s g_tasklisttable[NUM_TASK_STATES];
#ifdef CONFIG_SCHED_CPULOAD
/* This is the total number of clock tick counts. Essentially the
* 'denominator' for all CPU load calculations.
*/
extern volatile uint32_t g_cpuload_total;
#endif
/* Declared in sched_lock.c *************************************************/
/* Pre-emption is disabled via the interface sched_lock(). sched_lock()
* works by preventing context switches from the currently executing tasks.
* This prevents other tasks from running (without disabling interrupts) and
* gives the currently executing task exclusive access to the (single) CPU
* resources. Thus, sched_lock() and its companion, sched_unlcok(), are
* used to implement some critical sections.
*
* In the single CPU case, Pre-emption is disabled using a simple lockcount
* in the TCB. When the scheduling is locked, the lockcount is incremented;
* when the scheduler is unlocked, the lockcount is decremented. If the
* lockcount for the task at the head of the g_readytorun list has a
* lockcount > 0, then pre-emption is disabled.
*
* No special protection is required since only the executing task can
* modify its lockcount.
*/
#ifdef CONFIG_SMP
/* In the multiple CPU, SMP case, disabling context switches will not give a
* task exclusive access to the (multiple) CPU resources (at least without
* stopping the other CPUs): Even though pre-emption is disabled, other
* threads will still be executing on the other CPUS.
*
* There are additional rules for this multi-CPU case:
*
* 1. There is a global lock count 'g_cpu_lockset' that includes a bit for
* each CPU: If the bit is '1', then the corresponding CPU has the
* scheduler locked; if '0', then the CPU does not have the scheduler
* locked.
* 2. Scheduling logic would set the bit associated with the cpu in
* 'g_cpu_lockset' when the TCB at the head of the g_assignedtasks[cpu]
* list transitions has 'lockcount' > 0. This might happen when sched_lock()
* is called, or after a context switch that changes the TCB at the
* head of the g_assignedtasks[cpu] list.
* 3. Similarly, the cpu bit in the global 'g_cpu_lockset' would be cleared
* when the TCB at the head of the g_assignedtasks[cpu] list has
* 'lockcount' == 0. This might happen when sched_unlock() is called, or
* after a context switch that changes the TCB at the head of the
* g_assignedtasks[cpu] list.
* 4. Modification of the global 'g_cpu_lockset' must be protected by a
* spinlock, 'g_cpu_schedlock'. That spinlock would be taken when
* sched_lock() is called, and released when sched_unlock() is called.
* This assures that the scheduler does enforce the critical section.
* NOTE: Because of this spinlock, there should never be more than one
* bit set in 'g_cpu_lockset'; attempts to set additional bits should
* be cause the CPU to block on the spinlock. However, additional bits
* could get set in 'g_cpu_lockset' due to the context switches on the
* various CPUs.
* 5. Each the time the head of a g_assignedtasks[] list changes and the
* scheduler modifies 'g_cpu_lockset', it must also set 'g_cpu_schedlock'
* depending on the new state of 'g_cpu_lockset'.
* 5. Logic that currently uses the currently running tasks lockcount
* instead uses the global 'g_cpu_schedlock'. A value of SP_UNLOCKED
* means that no CPU has pre-emption disabled; SP_LOCKED means that at
* least one CPU has pre-emption disabled.
*/
extern volatile spinlock_t g_cpu_schedlock SP_SECTION;
/* Used to keep track of which CPU(s) hold the IRQ lock. */
extern volatile spinlock_t g_cpu_locksetlock SP_SECTION;
extern volatile cpu_set_t g_cpu_lockset SP_SECTION;
/* Used to lock tasklist to prevent from concurrent access */
extern volatile spinlock_t g_cpu_tasklistlock SP_SECTION;
#if defined(CONFIG_ARCH_HAVE_FETCHADD) && !defined(CONFIG_ARCH_GLOBAL_IRQDISABLE)
/* This is part of the sched_lock() logic to handle atomic operations when
* locking the scheduler.
*/
extern volatile int16_t g_global_lockcount;
#endif
#endif /* CONFIG_SMP */
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
/* Task list manipulation functions */
bool sched_addreadytorun(FAR struct tcb_s *rtrtcb);
bool sched_removereadytorun(FAR struct tcb_s *rtrtcb);
bool sched_addprioritized(FAR struct tcb_s *tcb, DSEG dq_queue_t *list);
void sched_mergeprioritized(FAR dq_queue_t *list1, FAR dq_queue_t *list2,
uint8_t task_state);
bool sched_mergepending(void);
void sched_addblocked(FAR struct tcb_s *btcb, tstate_t task_state);
void sched_removeblocked(FAR struct tcb_s *btcb);
int nxsched_setpriority(FAR struct tcb_s *tcb, int sched_priority);
/* Priority inheritance support */
#ifdef CONFIG_PRIORITY_INHERITANCE
int nxsched_reprioritize(FAR struct tcb_s *tcb, int sched_priority);
#else
# define nxsched_reprioritize(tcb,sched_priority) \
nxsched_setpriority(tcb,sched_priority)
#endif
/* Support for tickless operation */
#ifdef CONFIG_SCHED_TICKLESS
unsigned int sched_timer_cancel(void);
void sched_timer_resume(void);
void sched_timer_reassess(void);
#else
# define sched_timer_cancel() (0)
# define sched_timer_resume()
# define sched_timer_reassess()
#endif
/* Scheduler policy support */
#if CONFIG_RR_INTERVAL > 0
uint32_t sched_roundrobin_process(FAR struct tcb_s *tcb, uint32_t ticks,
bool noswitches);
#endif
#ifdef CONFIG_SCHED_SPORADIC
int sched_sporadic_initialize(FAR struct tcb_s *tcb);
int sched_sporadic_start(FAR struct tcb_s *tcb);
int sched_sporadic_stop(FAR struct tcb_s *tcb);
int sched_sporadic_reset(FAR struct tcb_s *tcb);
int sched_sporadic_resume(FAR struct tcb_s *tcb);
int sched_sporadic_suspend(FAR struct tcb_s *tcb);
uint32_t sched_sporadic_process(FAR struct tcb_s *tcb, uint32_t ticks,
bool noswitches);
void sched_sporadic_lowpriority(FAR struct tcb_s *tcb);
#endif
#ifdef CONFIG_SIG_SIGSTOP_ACTION
void sched_suspend(FAR struct tcb_s *tcb);
void sched_continue(FAR struct tcb_s *tcb);
#endif
#ifdef CONFIG_SMP
#if defined(CONFIG_ARCH_GLOBAL_IRQDISABLE) || defined(CONFIG_ARCH_HAVE_FETCHADD)
FAR struct tcb_s *this_task(void);
#endif
int sched_cpu_select(cpu_set_t affinity);
int sched_cpu_pause(FAR struct tcb_s *tcb);
irqstate_t sched_tasklist_lock(void);
void sched_tasklist_unlock(irqstate_t lock);
#if defined(CONFIG_ARCH_HAVE_FETCHADD) && !defined(CONFIG_ARCH_GLOBAL_IRQDISABLE)
# define sched_islocked_global() \
(spin_islocked(&g_cpu_schedlock) || g_global_lockcount > 0)
#else
# define sched_islocked_global() \
spin_islocked(&g_cpu_schedlock)
#endif
# define sched_islocked_tcb(tcb) sched_islocked_global()
#else
# define sched_cpu_select(a) (0)
# define sched_cpu_pause(t) (-38) /* -ENOSYS */
# define sched_islocked_tcb(tcb) ((tcb)->lockcount > 0)
#endif
#if defined(CONFIG_SCHED_CPULOAD) && !defined(CONFIG_SCHED_CPULOAD_EXTCLK)
/* CPU load measurement support */
void weak_function nxsched_process_cpuload(void);
#endif
/* Critical section monitor */
#ifdef CONFIG_SCHED_CRITMONITOR
void sched_critmon_preemption(FAR struct tcb_s *tcb, bool state);
void sched_critmon_csection(FAR struct tcb_s *tcb, bool state);
void sched_critmon_resume(FAR struct tcb_s *tcb);
void sched_critmon_suspend(FAR struct tcb_s *tcb);
#endif
/* TCB operations */
bool sched_verifytcb(FAR struct tcb_s *tcb);
int sched_releasetcb(FAR struct tcb_s *tcb, uint8_t ttype);
#endif /* __SCHED_SCHED_SCHED_H */
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