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

/*
 * Copyright (c) 2000-2005 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
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 * @APPLE_LICENSE_HEADER_END@
 */

#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)))

#endif	/* _MACH_THREAD_POLICY_H_ */