xnu-4903.221.2.tar.gz

[apple/xnu.git] / osfmk / kern / sched_prim.h

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 * 
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/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */
/*
 *	File:	sched_prim.h
 *	Author:	David Golub
 *
 *	Scheduling primitive definitions file
 *
 */

#ifndef	_KERN_SCHED_PRIM_H_
#define _KERN_SCHED_PRIM_H_

#include <mach/boolean.h>
#include <mach/machine/vm_types.h>
#include <mach/kern_return.h>
#include <kern/clock.h>
#include <kern/kern_types.h>
#include <kern/thread.h>
#include <sys/cdefs.h>
#include <kern/block_hint.h>

#ifdef	MACH_KERNEL_PRIVATE

/* Initialization */
extern void		sched_init(void);

extern void		sched_startup(void);

extern void		sched_timebase_init(void);

extern void		pset_rt_init(processor_set_t pset);

extern void		sched_rtglobal_init(processor_set_t pset);

extern rt_queue_t	sched_rtglobal_runq(processor_set_t pset);

extern void		sched_rtglobal_queue_shutdown(processor_t processor);

extern int64_t		sched_rtglobal_runq_count_sum(void);

extern void		sched_check_spill(processor_set_t pset, thread_t thread);

extern bool             sched_thread_should_yield(processor_t processor, thread_t thread);

/* Force a preemption point for a thread and wait for it to stop running */
extern boolean_t	thread_stop( 
						thread_t	thread,
						boolean_t	until_not_runnable);

/* Release a previous stop request */
extern void			thread_unstop(
						thread_t	thread);

/* Wait for a thread to stop running */
extern void			thread_wait(
						thread_t	thread,
						boolean_t	until_not_runnable);

/* Unblock thread on wake up */
extern boolean_t	thread_unblock(
						thread_t		thread,
						wait_result_t	wresult);

/* Unblock and dispatch thread */
extern kern_return_t	thread_go(
						 	thread_t		thread,
							wait_result_t	wresult);

/* Handle threads at context switch */
extern void			thread_dispatch(
						thread_t		old_thread,
						thread_t		new_thread);

/* Switch directly to a particular thread */
extern int			thread_run(
						thread_t			self,
						thread_continue_t	continuation,
						void				*parameter,
						thread_t			new_thread);

/* Resume thread with new stack */
extern void			thread_continue(
						thread_t		old_thread);

/* Invoke continuation */
extern void		call_continuation(
					thread_continue_t	continuation,
					void				*parameter,
					wait_result_t		wresult,
					boolean_t           enable_interrupts);

/*
 * Flags that can be passed to set_sched_pri
 * to skip side effects
 */
typedef enum {
	SETPRI_DEFAULT  = 0x0,
	SETPRI_LAZY     = 0x1,  /* Avoid setting AST flags or sending IPIs */
} set_sched_pri_options_t;

/* Set the current scheduled priority */
extern void set_sched_pri(
                          thread_t      thread,
                          int           priority,
                          set_sched_pri_options_t options);

/* Set base priority of the specified thread */
extern void		sched_set_thread_base_priority(
					thread_t		thread,
					int				priority);

/* Set the thread's true scheduling mode */
extern void             sched_set_thread_mode(thread_t thread,
                                              sched_mode_t mode);
/* Demote the true scheduler mode */
extern void             sched_thread_mode_demote(thread_t thread,
                                                 uint32_t reason);
/* Un-demote the true scheduler mode */
extern void             sched_thread_mode_undemote(thread_t thread,
                                                   uint32_t reason);

extern void sched_thread_promote_to_pri(thread_t thread, int priority, uintptr_t trace_obj);
extern void sched_thread_update_promotion_to_pri(thread_t thread, int priority, uintptr_t trace_obj);
extern void sched_thread_unpromote(thread_t thread, uintptr_t trace_obj);

extern void assert_promotions_invariant(thread_t thread);

extern void sched_thread_promote_reason(thread_t thread, uint32_t reason, uintptr_t trace_obj);
extern void sched_thread_unpromote_reason(thread_t thread, uint32_t reason, uintptr_t trace_obj);

/* Re-evaluate base priority of thread (thread locked) */
void thread_recompute_priority(thread_t thread);

/* Re-evaluate scheduled priority of thread (thread locked) */
extern void thread_recompute_sched_pri(
                                       thread_t thread,
                                       set_sched_pri_options_t options);

/* Periodic scheduler activity */
extern void		sched_init_thread(void (*)(void));

/* Perform sched_tick housekeeping activities */
extern boolean_t		can_update_priority(
					thread_t		thread);

extern void		update_priority(
											thread_t		thread);

extern void		lightweight_update_priority(
								thread_t		thread);

extern void             sched_default_quantum_expire(thread_t thread);

/* Idle processor thread */
extern void		idle_thread(void);

extern kern_return_t	idle_thread_create(
							processor_t		processor);

/* Continuation return from syscall */
extern void     thread_syscall_return(
                        kern_return_t   ret);

/* Context switch */
extern wait_result_t	thread_block_reason(
							thread_continue_t	continuation,
							void				*parameter,
							ast_t				reason);

/* Reschedule thread for execution */
extern void		thread_setrun(
					thread_t	thread,
					integer_t	options);

typedef enum {
	SCHED_NONE      = 0x0,
	SCHED_TAILQ     = 0x1,
	SCHED_HEADQ     = 0x2,
	SCHED_PREEMPT   = 0x4,
	SCHED_REBALANCE = 0x8,
} sched_options_t;

extern processor_set_t	task_choose_pset(
							task_t			task);

/* Bind the current thread to a particular processor */
extern processor_t		thread_bind(
							processor_t		processor);

/* Choose the best processor to run a thread */
extern processor_t	choose_processor(
									 processor_set_t		pset,
									 processor_t			processor,
									 thread_t			thread);

extern void sched_SMT_balance(
			      processor_t processor,
			      processor_set_t pset);

extern void thread_quantum_init(
								thread_t thread);

extern void		run_queue_init(
					run_queue_t		runq);

extern thread_t	run_queue_dequeue(
							  run_queue_t		runq,
							  integer_t		options);

extern boolean_t	run_queue_enqueue(
							  run_queue_t		runq,
							  thread_t			thread,
							  integer_t		options);

extern void	run_queue_remove(
									 run_queue_t		runq,
									 thread_t			thread);
									  
struct sched_update_scan_context
{
	uint64_t	earliest_bg_make_runnable_time;
	uint64_t	earliest_normal_make_runnable_time;
	uint64_t	earliest_rt_make_runnable_time;
};
typedef struct sched_update_scan_context *sched_update_scan_context_t;

extern void		sched_rtglobal_runq_scan(sched_update_scan_context_t scan_context);

/* 
 * Enum to define various events which need IPIs. The IPI policy 
 * engine decides what kind of IPI to use based on destination 
 * processor state, thread and one of the following scheduling events.
 */
typedef enum {
	SCHED_IPI_EVENT_BOUND_THR   = 0x1,
	SCHED_IPI_EVENT_PREEMPT	    = 0x2,
	SCHED_IPI_EVENT_SMT_REBAL   = 0x3,
	SCHED_IPI_EVENT_SPILL	    = 0x4,
	SCHED_IPI_EVENT_REBALANCE   = 0x5,
} sched_ipi_event_t;


/* Enum to define various IPI types used by the scheduler */
typedef enum {
	SCHED_IPI_NONE		    = 0x0,
	SCHED_IPI_IMMEDIATE	    = 0x1,
	SCHED_IPI_IDLE		    = 0x2,
	SCHED_IPI_DEFERRED	    = 0x3,
} sched_ipi_type_t;

/* The IPI policy engine behaves in the following manner:
 * - All scheduler events which need an IPI invoke sched_ipi_action() with  
 *   the appropriate destination processor, thread and event.
 * - sched_ipi_action() performs basic checks, invokes the scheduler specific
 *   ipi_policy routine and sets pending_AST bits based on the result.
 * - Once the pset lock is dropped, the scheduler invokes sched_ipi_perform()
 *   routine which actually sends the appropriate IPI to the destination core.
 */
extern sched_ipi_type_t sched_ipi_action(processor_t dst, thread_t thread,
         boolean_t dst_idle, sched_ipi_event_t event);
extern void sched_ipi_perform(processor_t dst, sched_ipi_type_t ipi);

/* sched_ipi_policy() is the global default IPI policy for all schedulers */
extern sched_ipi_type_t sched_ipi_policy(processor_t dst, thread_t thread,
         boolean_t dst_idle, sched_ipi_event_t event);

/* sched_ipi_deferred_policy() is the global default deferred IPI policy for all schedulers */
extern sched_ipi_type_t sched_ipi_deferred_policy(processor_set_t pset,
         processor_t dst, sched_ipi_event_t event);

#if defined(CONFIG_SCHED_TIMESHARE_CORE)

extern boolean_t        thread_update_add_thread(thread_t thread);
extern void             thread_update_process_threads(void);
extern boolean_t        runq_scan(run_queue_t runq, sched_update_scan_context_t scan_context);

extern void sched_timeshare_init(void);
extern void sched_timeshare_timebase_init(void);
extern void sched_timeshare_maintenance_continue(void);

extern boolean_t priority_is_urgent(int priority);
extern uint32_t sched_timeshare_initial_quantum_size(thread_t thread);

extern int sched_compute_timeshare_priority(thread_t thread);

#endif /* CONFIG_SCHED_TIMESHARE_CORE */

/* Remove thread from its run queue */
extern boolean_t	thread_run_queue_remove(thread_t thread);
thread_t thread_run_queue_remove_for_handoff(thread_t thread);

/* Put a thread back in the run queue after being yanked */
extern void thread_run_queue_reinsert(thread_t thread, integer_t options);

extern void		thread_timer_expire(
					void			*thread,
					void			*p1);

extern boolean_t	thread_eager_preemption(
						thread_t thread);

extern boolean_t sched_generic_direct_dispatch_to_idle_processors;

/* Set the maximum interrupt level for the thread */
__private_extern__ wait_interrupt_t thread_interrupt_level(
						wait_interrupt_t interruptible);

__private_extern__ wait_result_t thread_mark_wait_locked(
						thread_t		 thread,
						wait_interrupt_t interruptible);

/* Wake up locked thread directly, passing result */
__private_extern__ kern_return_t clear_wait_internal(
						thread_t		thread,
						wait_result_t	result);

extern void sched_stats_handle_csw(
							processor_t processor, 
							int reasons, 
							int selfpri, 
							int otherpri);

extern void sched_stats_handle_runq_change(
									struct runq_stats *stats, 
									int old_count);


#if DEBUG

#define	SCHED_STATS_CSW(processor, reasons, selfpri, otherpri) 		\
do { 								\
	if (__builtin_expect(sched_stats_active, 0)) { 	\
		sched_stats_handle_csw((processor), 		\
				(reasons), (selfpri), (otherpri)); 	\
	}							\
} while (0) 


#define SCHED_STATS_RUNQ_CHANGE(stats, old_count)		\
do { 								\
	if (__builtin_expect(sched_stats_active, 0)) { 	\
		sched_stats_handle_runq_change((stats), 	\
								(old_count));		\
	}							\
} while (0) 

#else /* DEBUG */

#define SCHED_STATS_CSW(processor, reasons, selfpri, otherpri) do { }while(0)
#define SCHED_STATS_RUNQ_CHANGE(stats, old_count) do { }while(0)

#endif /* DEBUG */

extern uint32_t sched_debug_flags;
#define SCHED_DEBUG_FLAG_PLATFORM_TRACEPOINTS	0x00000001
#define SCHED_DEBUG_FLAG_CHOOSE_PROCESSOR_TRACEPOINTS	0x00000002

#define SCHED_DEBUG_PLATFORM_KERNEL_DEBUG_CONSTANT(...) do {						\
		if (__improbable(sched_debug_flags & SCHED_DEBUG_FLAG_PLATFORM_TRACEPOINTS)) { \
			KERNEL_DEBUG_CONSTANT(__VA_ARGS__);							\
		}																\
	} while(0)

#define SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(...) do {						\
		if (__improbable(sched_debug_flags & SCHED_DEBUG_FLAG_CHOOSE_PROCESSOR_TRACEPOINTS)) { \
			KERNEL_DEBUG_CONSTANT(__VA_ARGS__);							\
		}																\
	} while(0)

#define THREAD_URGENCY_NONE		0	/* indicates that there is no currently runnable */
#define THREAD_URGENCY_BACKGROUND	1	/* indicates that the thread is marked as a "background" thread */
#define THREAD_URGENCY_NORMAL		2	/* indicates that the thread is marked as a "normal" thread */
#define THREAD_URGENCY_REAL_TIME	3	/* indicates that the thread is marked as a "real-time" or urgent thread */
#define	THREAD_URGENCY_MAX		4	/* Marker */
/* Returns the "urgency" of a thread (provided by scheduler) */
extern int	thread_get_urgency(
					thread_t	thread,
    				   	uint64_t	*rt_period,
					uint64_t	*rt_deadline);

/* Tells the "urgency" of the just scheduled thread (provided by CPU PM) */
extern void	thread_tell_urgency(
    					int		urgency,
					uint64_t	rt_period,
					uint64_t	rt_deadline,
					uint64_t	sched_latency,
				    thread_t nthread);

/* Tells if there are "active" RT threads in the system (provided by CPU PM) */
extern void	active_rt_threads(
    					boolean_t	active);

/* Returns the perfcontrol attribute for the thread */
extern perfcontrol_class_t thread_get_perfcontrol_class(
					thread_t	thread);

/* Generic routine for Non-AMP schedulers to calculate parallelism */
extern uint32_t sched_qos_max_parallelism(int qos, uint64_t options);

#endif /* MACH_KERNEL_PRIVATE */

__BEGIN_DECLS

#ifdef	XNU_KERNEL_PRIVATE

/* Toggles a global override to turn off CPU Throttling */
extern void	sys_override_cpu_throttle(boolean_t enable_override);

/*
 ****************** Only exported until BSD stops using ********************
 */

extern void			thread_vm_bind_group_add(void);

/* Wake up thread directly, passing result */
extern kern_return_t clear_wait(
						thread_t		thread,
						wait_result_t	result);

/* Start thread running */
extern void		thread_bootstrap_return(void) __attribute__((noreturn));

/* Return from exception (BSD-visible interface) */
extern void		thread_exception_return(void) __dead2;

#define SCHED_STRING_MAX_LENGTH (48)
/* String declaring the name of the current scheduler */
extern char sched_string[SCHED_STRING_MAX_LENGTH];

extern thread_t port_name_to_thread_for_ulock(mach_port_name_t	thread_name);

/* Attempt to context switch to a specific runnable thread */
extern wait_result_t thread_handoff_deallocate(thread_t thread);

__attribute__((nonnull(1, 2)))
extern void thread_handoff_parameter(thread_t thread,
		thread_continue_t continuation, void *parameter) __dead2;

extern struct waitq	*assert_wait_queue(event_t event);

extern kern_return_t thread_wakeup_one_with_pri(event_t event, int priority);

extern thread_t thread_wakeup_identify(event_t event, int priority);

#endif	/* XNU_KERNEL_PRIVATE */

#ifdef KERNEL_PRIVATE
/* Set pending block hint for a particular object before we go into a wait state */
extern void		thread_set_pending_block_hint(
							thread_t			thread,
							block_hint_t			block_hint);

#define QOS_PARALLELISM_COUNT_LOGICAL   0x1
#define QOS_PARALLELISM_REALTIME        0x2
extern uint32_t qos_max_parallelism(int qos, uint64_t options);
#endif /* KERNEL_PRIVATE */

#if XNU_KERNEL_PRIVATE
extern void		thread_yield_with_continuation(
						thread_continue_t	continuation,
						void				*parameter) __dead2;
#endif

/* Context switch */
extern wait_result_t	thread_block(
							thread_continue_t	continuation);

extern wait_result_t	thread_block_parameter(
							thread_continue_t	continuation,
							void				*parameter);

/* Declare thread will wait on a particular event */
extern wait_result_t	assert_wait(
							event_t				event,
							wait_interrupt_t	interruptible);

/* Assert that the thread intends to wait with a timeout */
extern wait_result_t	assert_wait_timeout(
							event_t				event,
							wait_interrupt_t	interruptible,
							uint32_t			interval,
							uint32_t			scale_factor);

/* Assert that the thread intends to wait with an urgency, timeout and leeway */
extern wait_result_t	assert_wait_timeout_with_leeway(
							event_t				event,
							wait_interrupt_t	interruptible,
							wait_timeout_urgency_t	urgency,
							uint32_t			interval,
							uint32_t			leeway,
							uint32_t			scale_factor);

extern wait_result_t	assert_wait_deadline(
							event_t				event,
							wait_interrupt_t	interruptible,
							uint64_t			deadline);

/* Assert that the thread intends to wait with an urgency, deadline, and leeway */
extern wait_result_t	assert_wait_deadline_with_leeway(
							event_t				event,
							wait_interrupt_t	interruptible,
							wait_timeout_urgency_t	urgency,
							uint64_t			deadline,
							uint64_t			leeway);

/* Wake up thread (or threads) waiting on a particular event */
extern kern_return_t	thread_wakeup_prim(
							event_t				event,
							boolean_t			one_thread,
							wait_result_t			result);

#define thread_wakeup(x)					\
			thread_wakeup_prim((x), FALSE, THREAD_AWAKENED)
#define thread_wakeup_with_result(x, z)		\
			thread_wakeup_prim((x), FALSE, (z))
#define thread_wakeup_one(x)				\
			thread_wakeup_prim((x), TRUE, THREAD_AWAKENED)

/* Wakeup the specified thread if it is waiting on this event */
extern kern_return_t thread_wakeup_thread(event_t event, thread_t thread);

extern boolean_t preemption_enabled(void);

#ifdef MACH_KERNEL_PRIVATE

/*
 * Scheduler algorithm indirection. If only one algorithm is
 * enabled at compile-time, a direction function call is used.
 * If more than one is enabled, calls are dispatched through
 * a function pointer table.
 */

#if   !defined(CONFIG_SCHED_TRADITIONAL) && !defined(CONFIG_SCHED_PROTO) && !defined(CONFIG_SCHED_GRRR) && !defined(CONFIG_SCHED_MULTIQ)
#error Enable at least one scheduler algorithm in osfmk/conf/MASTER.XXX
#endif

#if DEBUG
#define SCHED(f) (sched_current_dispatch->f)
#else /* DEBUG */

/* 
 * For DEV & REL kernels, use a static dispatch table instead of 
 * using the indirect function table.
 */
extern const struct sched_dispatch_table sched_dualq_dispatch;
#define SCHED(f) (sched_dualq_dispatch.f)

#endif /* DEBUG */

struct sched_dispatch_table {
	const char *sched_name;
	void	(*init)(void);				/* Init global state */
	void	(*timebase_init)(void);		/* Timebase-dependent initialization */
	void	(*processor_init)(processor_t processor);	/* Per-processor scheduler init */
	void	(*pset_init)(processor_set_t pset);	/* Per-processor set scheduler init */

	void	(*maintenance_continuation)(void);	/* Function called regularly */

	/*
	 * Choose a thread of greater or equal priority from the per-processor
	 * runqueue for timeshare/fixed threads
	 */
	thread_t	(*choose_thread)(
								  processor_t		processor,
								  int				priority,
								  ast_t reason);

	/* True if scheduler supports stealing threads */
	boolean_t   steal_thread_enabled;

	/*
	 * Steal a thread from another processor in the pset so that it can run
	 * immediately
	 */
	thread_t	(*steal_thread)(
								processor_set_t		pset);

	/*
	 * Compute priority for a timeshare thread based on base priority.
	 */
	int (*compute_timeshare_priority)(thread_t thread);

	/*
	 * Pick the best processor for a thread (any kind of thread) to run on.
	 */
	processor_t	(*choose_processor)(
										 processor_set_t		pset,
										 processor_t			processor,
										 thread_t			thread);
	/*
	 * Enqueue a timeshare or fixed priority thread onto the per-processor
	 * runqueue
	 */
	boolean_t (*processor_enqueue)(
								 processor_t			processor,
								 thread_t			thread,
								 integer_t			options);

	/* Migrate threads away in preparation for processor shutdown */
	void (*processor_queue_shutdown)(
									 processor_t			processor);

	/* Remove the specific thread from the per-processor runqueue */
	boolean_t	(*processor_queue_remove)(
									processor_t		processor,
									thread_t		thread);

	/*
	 * Does the per-processor runqueue have any timeshare or fixed priority
	 * threads on it? Called without pset lock held, so should
	 * not assume immutability while executing.
	 */
	boolean_t	(*processor_queue_empty)(processor_t		processor);

	/*
	 * Would this priority trigger an urgent preemption if it's sitting
	 * on the per-processor runqueue?
	 */
	boolean_t	(*priority_is_urgent)(int priority);

	/*
	 * Does the per-processor runqueue contain runnable threads that
	 * should cause the currently-running thread to be preempted?
	 */
	ast_t		(*processor_csw_check)(processor_t processor);

	/*
	 * Does the per-processor runqueue contain a runnable thread
	 * of > or >= priority, as a preflight for choose_thread() or other
	 * thread selection
	 */
	boolean_t	(*processor_queue_has_priority)(processor_t		processor,
												int				priority,
												boolean_t		gte);

	/* Quantum size for the specified non-realtime thread. */
	uint32_t	(*initial_quantum_size)(thread_t thread);
	
	/* Scheduler mode for a new thread */
	sched_mode_t	(*initial_thread_sched_mode)(task_t parent_task);

	/*
	 * Is it safe to call update_priority, which may change a thread's
	 * runqueue or other state. This can be used to throttle changes
	 * to dynamic priority.
	 */
	boolean_t	(*can_update_priority)(thread_t thread);

	/*
	 * Update both scheduled priority and other persistent state.
	 * Side effects may including migration to another processor's runqueue.
	 */
	void		(*update_priority)(thread_t thread);

	/* Lower overhead update to scheduled priority and state. */
	void		(*lightweight_update_priority)(thread_t thread);

	/* Callback for non-realtime threads when the quantum timer fires */
	void		(*quantum_expire)(thread_t thread);

	/*
	 * Runnable threads on per-processor runqueue. Should only
	 * be used for relative comparisons of load between processors.
	 */
	int			(*processor_runq_count)(processor_t	processor);

	/* Aggregate runcount statistics for per-processor runqueue */
	uint64_t    (*processor_runq_stats_count_sum)(processor_t   processor);

	boolean_t	(*processor_bound_count)(processor_t processor);

	void		(*thread_update_scan)(sched_update_scan_context_t scan_context);

	/*
	* Use processor->next_thread to pin a thread to an idle
	* processor. If FALSE, threads are enqueued and can
	* be stolen by other processors.
	*/
	boolean_t   direct_dispatch_to_idle_processors;

	/* Supports more than one pset */
	boolean_t   multiple_psets_enabled;
	/* Supports scheduler groups */
	boolean_t   sched_groups_enabled;

	/* Supports avoid-processor */
	boolean_t   avoid_processor_enabled;

	/* Returns true if this processor should avoid running this thread. */
	bool    (*thread_avoid_processor)(processor_t processor, thread_t thread);

	/*
	 * Invoked when a processor is about to choose the idle thread
	 * Used to send IPIs to a processor which would be preferred to be idle instead.
	 * Called with pset lock held, returns pset lock unlocked.
	 */
	void    (*processor_balance)(processor_t processor, processor_set_t pset);
	rt_queue_t	(*rt_runq)(processor_set_t pset);
	void	(*rt_init)(processor_set_t pset);
	void	(*rt_queue_shutdown)(processor_t processor);
	void	(*rt_runq_scan)(sched_update_scan_context_t scan_context);
	int64_t	(*rt_runq_count_sum)(void);

	uint32_t (*qos_max_parallelism)(int qos, uint64_t options);
	void	(*check_spill)(processor_set_t pset, thread_t thread);
	sched_ipi_type_t (*ipi_policy)(processor_t dst, thread_t thread, boolean_t dst_idle, sched_ipi_event_t event);
	bool    (*thread_should_yield)(processor_t processor, thread_t thread);
};

#if defined(CONFIG_SCHED_TRADITIONAL)
extern const struct sched_dispatch_table sched_traditional_dispatch;
extern const struct sched_dispatch_table sched_traditional_with_pset_runqueue_dispatch;
#endif

#if defined(CONFIG_SCHED_MULTIQ)
extern const struct sched_dispatch_table sched_multiq_dispatch;
extern const struct sched_dispatch_table sched_dualq_dispatch;
#endif

#if defined(CONFIG_SCHED_PROTO)
extern const struct sched_dispatch_table sched_proto_dispatch;
#endif

#if defined(CONFIG_SCHED_GRRR)
extern const struct sched_dispatch_table sched_grrr_dispatch;
#endif

/*
 * It is an error to invoke any scheduler-related code
 * before this is set up
 */
extern const struct sched_dispatch_table *sched_current_dispatch;

#endif	/* MACH_KERNEL_PRIVATE */

__END_DECLS

#endif	/* _KERN_SCHED_PRIM_H_ */