xnu-3247.10.11.tar.gz

[apple/xnu.git] / osfmk / mach / thread_policy.h

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 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
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 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
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#ifndef _MACH_THREAD_POLICY_H_
#define _MACH_THREAD_POLICY_H_

#include <mach/mach_types.h>

/*
 * These are the calls for accessing the policy parameters
 * of a particular thread.
 *
 * The extra 'get_default' parameter to the second call is
 * IN/OUT as follows:
 * 1) if asserted on the way in it indicates that the default
 * values should be returned, not the ones currently set, in
 * this case 'get_default' will always be asserted on return;
 * 2) if unasserted on the way in, the current settings are
 * desired and if still unasserted on return, then the info
 * returned reflects the current settings, otherwise if
 * 'get_default' returns asserted, it means that there are no
 * current settings due to other parameters taking precedence,
 * and the default ones are being returned instead.
 */

typedef natural_t	thread_policy_flavor_t;
typedef integer_t	*thread_policy_t;

/*
kern_return_t	thread_policy_set(
					thread_t					thread,
					thread_policy_flavor_t		flavor,
					thread_policy_t				policy_info,
					mach_msg_type_number_t		count);

kern_return_t	thread_policy_get(
					thread_t					thread,
					thread_policy_flavor_t		flavor,
					thread_policy_t				policy_info,
					mach_msg_type_number_t		*count,
					boolean_t					*get_default);
*/

/*
 * Defined flavors.
 */
/*
 * THREAD_STANDARD_POLICY:
 *
 * This is the standard (fair) scheduling mode, assigned to new
 * threads.  The thread will be given processor time in a manner
 * which apportions approximately equal share to long running
 * computations.
 *
 * Parameters:
 *	[none]
 */

#define THREAD_STANDARD_POLICY			1

struct thread_standard_policy {
	natural_t		no_data;
};

typedef struct thread_standard_policy	thread_standard_policy_data_t;
typedef struct thread_standard_policy	*thread_standard_policy_t;

#define THREAD_STANDARD_POLICY_COUNT	0

/*
 * THREAD_EXTENDED_POLICY:
 *
 * Extended form of THREAD_STANDARD_POLICY, which supplies a
 * hint indicating whether this is a long running computation.
 *
 * Parameters:
 *
 * timeshare: TRUE (the default) results in identical scheduling
 * behavior as THREAD_STANDARD_POLICY.
 */

#define THREAD_EXTENDED_POLICY			1

struct thread_extended_policy {
	boolean_t		timeshare;
};

typedef struct thread_extended_policy	thread_extended_policy_data_t;
typedef struct thread_extended_policy	*thread_extended_policy_t;

#define THREAD_EXTENDED_POLICY_COUNT	((mach_msg_type_number_t) \
	(sizeof (thread_extended_policy_data_t) / sizeof (integer_t)))

/*
 * THREAD_TIME_CONSTRAINT_POLICY:
 *
 * This scheduling mode is for threads which have real time
 * constraints on their execution.
 *
 * Parameters:
 *
 * period: This is the nominal amount of time between separate
 * processing arrivals, specified in absolute time units.  A
 * value of 0 indicates that there is no inherent periodicity in
 * the computation.
 *
 * computation: This is the nominal amount of computation
 * time needed during a separate processing arrival, specified
 * in absolute time units.
 *
 * constraint: This is the maximum amount of real time that
 * may elapse from the start of a separate processing arrival
 * to the end of computation for logically correct functioning,
 * specified in absolute time units.  Must be (>= computation).
 * Note that latency = (constraint - computation).
 *
 * preemptible: This indicates that the computation may be
 * interrupted, subject to the constraint specified above.
 */

#define THREAD_TIME_CONSTRAINT_POLICY	2

struct thread_time_constraint_policy {
	uint32_t		period;
	uint32_t		computation;
	uint32_t		constraint;
	boolean_t		preemptible;
};

typedef struct thread_time_constraint_policy	\
									thread_time_constraint_policy_data_t;
typedef struct thread_time_constraint_policy	\
									*thread_time_constraint_policy_t;

#define THREAD_TIME_CONSTRAINT_POLICY_COUNT	((mach_msg_type_number_t) \
	(sizeof (thread_time_constraint_policy_data_t) / sizeof (integer_t)))

/*
 * THREAD_PRECEDENCE_POLICY:
 *
 * This may be used to indicate the relative value of the
 * computation compared to the other threads in the task.
 *
 * Parameters:
 *
 * importance: The importance is specified as a signed value.
 */

#define THREAD_PRECEDENCE_POLICY		3

struct thread_precedence_policy {
	integer_t		importance;
};

typedef struct thread_precedence_policy		thread_precedence_policy_data_t;
typedef struct thread_precedence_policy		*thread_precedence_policy_t;

#define THREAD_PRECEDENCE_POLICY_COUNT	((mach_msg_type_number_t) \
	(sizeof (thread_precedence_policy_data_t) / sizeof (integer_t)))

/*
 * THREAD_AFFINITY_POLICY:
 *
 * This policy is experimental.
 * This may be used to express affinity relationships 
 * between threads in the task. Threads with the same affinity tag will
 * be scheduled to share an L2 cache if possible. That is, affinity tags
 * are a hint to the scheduler for thread placement. 
 *
 * The namespace of affinity tags is generally local to one task. However,
 * a child task created after the assignment of affinity tags by its parent
 * will share that namespace. In particular, a family of forked processes
 * may be created with a shared affinity namespace.
 *
 * Parameters:
 * tag: The affinity set identifier.
 */

#define THREAD_AFFINITY_POLICY		4

struct thread_affinity_policy {
	integer_t	affinity_tag;
};

#define THREAD_AFFINITY_TAG_NULL		0

typedef struct thread_affinity_policy		thread_affinity_policy_data_t;
typedef struct thread_affinity_policy		*thread_affinity_policy_t;

#define THREAD_AFFINITY_POLICY_COUNT	((mach_msg_type_number_t) \
	(sizeof (thread_affinity_policy_data_t) / sizeof (integer_t)))

/*
 * THREAD_BACKGROUND_POLICY:
 */

#define THREAD_BACKGROUND_POLICY	5

struct thread_background_policy {
	integer_t	priority;
};

typedef struct thread_background_policy		thread_background_policy_data_t;
typedef struct thread_background_policy 	*thread_background_policy_t;

#define THREAD_BACKGROUND_POLICY_COUNT	((mach_msg_type_number_t) \
	(sizeof (thread_background_policy_data_t) / sizeof (integer_t)))


#define THREAD_LATENCY_QOS_POLICY	7
typedef integer_t	thread_latency_qos_t;

struct thread_latency_qos_policy {
	thread_latency_qos_t thread_latency_qos_tier;
};

typedef struct thread_latency_qos_policy	thread_latency_qos_policy_data_t;
typedef struct thread_latency_qos_policy 	*thread_latency_qos_policy_t;

#define THREAD_LATENCY_QOS_POLICY_COUNT	((mach_msg_type_number_t)	\
	    (sizeof (thread_latency_qos_policy_data_t) / sizeof (integer_t)))

#define THREAD_THROUGHPUT_QOS_POLICY	8
typedef integer_t	thread_throughput_qos_t;

struct thread_throughput_qos_policy {
	thread_throughput_qos_t thread_throughput_qos_tier;
};

typedef struct thread_throughput_qos_policy	thread_throughput_qos_policy_data_t;
typedef struct thread_throughput_qos_policy 	*thread_throughput_qos_policy_t;

#define THREAD_THROUGHPUT_QOS_POLICY_COUNT	((mach_msg_type_number_t) \
	    (sizeof (thread_throughput_qos_policy_data_t) / sizeof (integer_t)))

#ifdef PRIVATE

/*
 * THREAD_POLICY_STATE:
 */
#define THREAD_POLICY_STATE		6

#define THREAD_POLICY_STATE_FLAG_STATIC_PARAM   0x1

struct thread_policy_state {
	integer_t requested;
	integer_t effective;
	integer_t pending;
	integer_t flags;
	integer_t reserved[12];
};

typedef struct thread_policy_state		thread_policy_state_data_t;
typedef struct thread_policy_state		*thread_policy_state_t;

#define THREAD_POLICY_STATE_COUNT	((mach_msg_type_number_t) \
	(sizeof (thread_policy_state_data_t) / sizeof (integer_t)))

/*
 * THREAD_QOS_POLICY:
 */
#define THREAD_QOS_POLICY               9
#define THREAD_QOS_POLICY_OVERRIDE      10

#define THREAD_QOS_UNSPECIFIED          0
#define THREAD_QOS_DEFAULT              THREAD_QOS_UNSPECIFIED  /* Temporary rename */
#define THREAD_QOS_MAINTENANCE          1
#define THREAD_QOS_BACKGROUND           2
#define THREAD_QOS_UTILITY              3
#define THREAD_QOS_LEGACY               4       /* i.e. default workq threads */
#define THREAD_QOS_USER_INITIATED       5
#define THREAD_QOS_USER_INTERACTIVE     6

#define THREAD_QOS_LAST                 7

#define THREAD_QOS_MIN_TIER_IMPORTANCE	(-15)

/*
 * Overrides are inputs to the task/thread policy engine that
 * temporarily elevate the effective QoS of a thread without changing
 * its steady-state (and round-trip-able) requested QoS. The
 * interfaces into the kernel allow the caller to associate a resource
 * and type that describe the reason/lifecycle of the override. For
 * instance, a contended pthread_mutex_t held by a UTILITY thread
 * might get an override to USER_INTERACTIVE, with the resource
 * being the userspace address of the pthread_mutex_t. When the
 * owning thread releases that resource, it can call into the
 * task policy subsystem to drop the override because of that resource,
 * although if more contended locks are held by the thread, the
 * effective QoS may remain overridden for longer.
 *
 * THREAD_QOS_OVERRIDE_TYPE_PTHREAD_MUTEX is used for contended
 * pthread_mutex_t's via the pthread kext. The holder gets an override
 * with resource=&mutex and a count of 1 by the initial contender.
 * Subsequent contenders raise the QoS value, until the holder
 * decrements the count to 0 and the override is released.
 *
 * THREAD_QOS_OVERRIDE_TYPE_PTHREAD_RWLOCK is unimplemented and has no
 * specified semantics.
 *
 * THREAD_QOS_OVERRIDE_TYPE_PTHREAD_EXPLICIT_OVERRIDE are explicitly
 * paired start/end overrides on a target thread. The resource can
 * either be a memory allocation in userspace, or the pthread_t of the
 * overrider if no allocation was used.
 *
 * THREAD_QOS_OVERRIDE_TYPE_DISPATCH_ASYNCHRONOUS_OVERRIDE are used to
 * override the QoS of a thread currently draining a serial dispatch
 * queue, so that it can get to a block of higher QoS than its
 * predecessors. The override is applied by a thread enqueueing work
 * with resource=&queue, and reset by the thread that was overriden
 * once it has drained the queue. Since the ++ and reset are
 * asynchronous, there is the possibility of a ++ after the target
 * thread has issued a reset, in which case the workqueue thread may
 * issue a reset-all in its outermost scope before deciding whether it
 * should return to dequeueing work from the global concurrent queues,
 * or return to the kernel.
 */

#define THREAD_QOS_OVERRIDE_TYPE_UNKNOWN					(0)
#define THREAD_QOS_OVERRIDE_TYPE_PTHREAD_MUTEX				(1)
#define THREAD_QOS_OVERRIDE_TYPE_PTHREAD_RWLOCK				(2)
#define THREAD_QOS_OVERRIDE_TYPE_PTHREAD_EXPLICIT_OVERRIDE	(3)
#define THREAD_QOS_OVERRIDE_TYPE_DISPATCH_ASYNCHRONOUS_OVERRIDE	(4)

/* A special resource value to indicate a resource wildcard */
#define THREAD_QOS_OVERRIDE_RESOURCE_WILDCARD (~((user_addr_t)0))

struct thread_qos_policy {
	integer_t qos_tier;
	integer_t tier_importance;
};

typedef struct thread_qos_policy       thread_qos_policy_data_t;
typedef struct thread_qos_policy      *thread_qos_policy_t;

#define THREAD_QOS_POLICY_COUNT    ((mach_msg_type_number_t) \
        (sizeof (thread_qos_policy_data_t) / sizeof (integer_t)))

#endif /* PRIVATE */

#endif	/* _MACH_THREAD_POLICY_H_ */