[apple/xnu.git] / osfmk / kern / syscall_subr.c

/*
 * Copyright (c) 2000-2008 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * 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
 * 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, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * @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.
 */
/*
 */

#include <mach/boolean.h>
#include <mach/thread_switch.h>
#include <ipc/ipc_port.h>
#include <ipc/ipc_space.h>
#include <kern/counters.h>
#include <kern/ipc_kobject.h>
#include <kern/processor.h>
#include <kern/sched.h>
#include <kern/sched_prim.h>
#include <kern/spl.h>
#include <kern/task.h>
#include <kern/thread.h>
#include <mach/policy.h>

#include <kern/syscall_subr.h>
#include <mach/mach_host_server.h>
#include <mach/mach_syscalls.h>

/*
 *	swtch and swtch_pri both attempt to context switch (logic in
 *	thread_block no-ops the context switch if nothing would happen).
 *	A boolean is returned that indicates whether there is anything
 *	else runnable.
 *
 *	This boolean can be used by a thread waiting on a
 *	lock or condition:  If FALSE is returned, the thread is justified
 *	in becoming a resource hog by continuing to spin because there's
 *	nothing else useful that the processor could do.  If TRUE is
 *	returned, the thread should make one more check on the
 *	lock and then be a good citizen and really suspend.
 */

static void
swtch_continue(void)
{
	register processor_t	myprocessor;
    boolean_t				result;

    disable_preemption();
	myprocessor = current_processor();
	result = myprocessor->runq.count > 0 || rt_runq.count > 0;
	enable_preemption();

	thread_syscall_return(result);
	/*NOTREACHED*/
}

boolean_t
swtch(
	__unused struct swtch_args *args)
{
	register processor_t	myprocessor;
	boolean_t				result;

	disable_preemption();
	myprocessor = current_processor();
	if (myprocessor->runq.count == 0 &&	rt_runq.count == 0) {
		mp_enable_preemption();

		return (FALSE);
	}
	enable_preemption();

	counter(c_swtch_block++);

	thread_block_reason((thread_continue_t)swtch_continue, NULL, AST_YIELD);

	disable_preemption();
	myprocessor = current_processor();
	result = myprocessor->runq.count > 0 || rt_runq.count > 0;
	enable_preemption();

	return (result);
}

static void
swtch_pri_continue(void)
{
	register processor_t	myprocessor;
    boolean_t				result;

	thread_depress_abort_internal(current_thread());

    disable_preemption();
	myprocessor = current_processor();
	result = myprocessor->runq.count > 0 || rt_runq.count > 0;
	mp_enable_preemption();

	thread_syscall_return(result);
	/*NOTREACHED*/
}

boolean_t
swtch_pri(
__unused	struct swtch_pri_args *args)
{
	register processor_t	myprocessor;
	boolean_t				result;

	disable_preemption();
	myprocessor = current_processor();
	if (myprocessor->runq.count == 0 && rt_runq.count == 0) {
		mp_enable_preemption();

		return (FALSE);
	}
	enable_preemption();

	counter(c_swtch_pri_block++);

	thread_depress_abstime(std_quantum);

	thread_block_reason((thread_continue_t)swtch_pri_continue, NULL, AST_YIELD);

	thread_depress_abort_internal(current_thread());

	disable_preemption();
	myprocessor = current_processor();
	result = myprocessor->runq.count > 0 || rt_runq.count > 0;
	enable_preemption();

	return (result);
}

static void
thread_switch_continue(void)
{
	register thread_t	self = current_thread();
	int					option = self->saved.swtch.option;

	if (option == SWITCH_OPTION_DEPRESS)
		thread_depress_abort_internal(self);

	thread_syscall_return(KERN_SUCCESS);
	/*NOTREACHED*/
}

/*
 *	thread_switch:
 *
 *	Context switch.  User may supply thread hint.
 */
kern_return_t
thread_switch(
	struct thread_switch_args *args)
{
	register thread_t		thread, self = current_thread();
	mach_port_name_t		thread_name = args->thread_name;
	int						option = args->option;
	mach_msg_timeout_t		option_time = args->option_time;

    /*
     *	Process option.
     */
    switch (option) {

	case SWITCH_OPTION_NONE:
	case SWITCH_OPTION_DEPRESS:
	case SWITCH_OPTION_WAIT:
	    break;

	default:
	    return (KERN_INVALID_ARGUMENT);
    }

	/*
	 * Translate the port name if supplied.
	 */
    if (thread_name != MACH_PORT_NULL) {
		ipc_port_t			port;

		if (ipc_port_translate_send(self->task->itk_space,
									thread_name, &port) == KERN_SUCCESS) {
			ip_reference(port);
			ip_unlock(port);

			thread = convert_port_to_thread(port);
			ipc_port_release(port);

			if (thread == self) {
				(void)thread_deallocate_internal(thread);
				thread = THREAD_NULL;
			}
		}
		else
			thread = THREAD_NULL;
	}
	else
		thread = THREAD_NULL;

	/*
	 * Try to handoff if supplied.
	 */
	if (thread != THREAD_NULL) {
		processor_t		processor;
		spl_t			s;

		s = splsched();
		thread_lock(thread);

		/*
		 *	Check that the thread is not bound
		 *	to a different processor, and that realtime
		 *	is not involved.
		 *
		 *	Next, pull it off its run queue.  If it
		 *	doesn't come, it's not eligible.
		 */
		processor = current_processor();
		if (processor->current_pri < BASEPRI_RTQUEUES			&&
			thread->sched_pri < BASEPRI_RTQUEUES				&&
			(thread->bound_processor == PROCESSOR_NULL	||
			 thread->bound_processor == processor)				&&
				run_queue_remove(thread)							) {
			/*
			 *	Hah, got it!!
			 */
			thread_unlock(thread);

			(void)thread_deallocate_internal(thread);

			if (option == SWITCH_OPTION_WAIT)
				assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE,
														option_time, 1000*NSEC_PER_USEC);
			else
			if (option == SWITCH_OPTION_DEPRESS)
				thread_depress_ms(option_time);

			self->saved.swtch.option = option;

			thread_run(self, (thread_continue_t)thread_switch_continue, NULL, thread);
			/* NOTREACHED */
		}

		thread_unlock(thread);
		splx(s);

		thread_deallocate(thread);
	}
		
	if (option == SWITCH_OPTION_WAIT)
		assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE, option_time, 1000*NSEC_PER_USEC);
	else
	if (option == SWITCH_OPTION_DEPRESS)
		thread_depress_ms(option_time);
	  
	self->saved.swtch.option = option;

	thread_block_reason((thread_continue_t)thread_switch_continue, NULL, AST_YIELD);

	if (option == SWITCH_OPTION_DEPRESS)
		thread_depress_abort_internal(self);

    return (KERN_SUCCESS);
}

/*
 * Depress thread's priority to lowest possible for the specified interval,
 * with a value of zero resulting in no timeout being scheduled.
 */
void
thread_depress_abstime(
	uint64_t				interval)
{
	register thread_t		self = current_thread();
	uint64_t				deadline;
    spl_t					s;

    s = splsched();
    thread_lock(self);
	if (!(self->sched_mode & TH_MODE_ISDEPRESSED)) {
		processor_t		myprocessor = self->last_processor;

		self->sched_pri = DEPRESSPRI;
		myprocessor->current_pri = self->sched_pri;
		self->sched_mode |= TH_MODE_DEPRESS;

		if (interval != 0) {
			clock_absolutetime_interval_to_deadline(interval, &deadline);
			if (!timer_call_enter(&self->depress_timer, deadline))
				self->depress_timer_active++;
		}
	}
	thread_unlock(self);
    splx(s);
}

void
thread_depress_ms(
	mach_msg_timeout_t		interval)
{
	uint64_t		abstime;

	clock_interval_to_absolutetime_interval(
							interval, 1000*NSEC_PER_USEC, &abstime);
	thread_depress_abstime(abstime);
}

/*
 *	Priority depression expiration.
 */
void
thread_depress_expire(
	void			*p0,
	__unused void	*p1)
{
	thread_t		thread = p0;
    spl_t			s;

    s = splsched();
    thread_lock(thread);
	if (--thread->depress_timer_active == 0) {
		thread->sched_mode &= ~TH_MODE_ISDEPRESSED;
		compute_priority(thread, FALSE);
	}
    thread_unlock(thread);
    splx(s);
}

/*
 *	Prematurely abort priority depression if there is one.
 */
kern_return_t
thread_depress_abort_internal(
	thread_t				thread)
{
    kern_return_t 			result = KERN_NOT_DEPRESSED;
    spl_t					s;

    s = splsched();
    thread_lock(thread);
	if (!(thread->sched_mode & TH_MODE_POLLDEPRESS)) {
		if (thread->sched_mode & TH_MODE_ISDEPRESSED) {
			thread->sched_mode &= ~TH_MODE_ISDEPRESSED;
			compute_priority(thread, FALSE);
			result = KERN_SUCCESS;
		}

		if (timer_call_cancel(&thread->depress_timer))
			thread->depress_timer_active--;
	}
	thread_unlock(thread);
    splx(s);

    return (result);
}

void
thread_poll_yield(
	thread_t		self)
{
	spl_t			s;

	assert(self == current_thread());

	s = splsched();
	if (!(self->sched_mode & (TH_MODE_REALTIME|TH_MODE_TIMESHARE))) {
		uint64_t			total_computation, abstime;

		abstime = mach_absolute_time();
		total_computation = abstime - self->computation_epoch;
		total_computation += self->computation_metered;
		if (total_computation >= max_poll_computation) {
			processor_t		myprocessor = current_processor();
			ast_t			preempt;

			thread_lock(self);
			if (!(self->sched_mode & TH_MODE_ISDEPRESSED)) {
				self->sched_pri = DEPRESSPRI;
				myprocessor->current_pri = self->sched_pri;
			}
			self->computation_epoch = abstime;
			self->computation_metered = 0;
			self->sched_mode |= TH_MODE_POLLDEPRESS;

			abstime += (total_computation >> sched_poll_yield_shift);
			if (!timer_call_enter(&self->depress_timer, abstime))
				self->depress_timer_active++;
			thread_unlock(self);

			if ((preempt = csw_check(myprocessor)) != AST_NONE)
				ast_on(preempt);
		}
	}
	splx(s);
}


void
thread_yield_internal(
	mach_msg_timeout_t	ms)
{
	processor_t	myprocessor;

	disable_preemption();
	myprocessor = current_processor();
	if (myprocessor->runq.count == 0 && rt_runq.count == 0) {
		mp_enable_preemption();

		return;
	}
	enable_preemption();

	thread_depress_ms(ms);

	thread_block_reason(THREAD_CONTINUE_NULL, NULL, AST_YIELD);

	thread_depress_abort_internal(current_thread());
}
Commit	Line	Data
1c79356b	1	/*
c910b4d9	2	* Copyright (c) 2000-2008 Apple Inc. All rights reserved.
1c79356b	3	*
2d21ac55	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
1c79356b	5	*
2d21ac55 A	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
8f6c56a5	14	*
2d21ac55 A	15	* Please obtain a copy of the License at
	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
	17	*
	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
8f6c56a5 A	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
8f6c56a5 A	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
2d21ac55 A	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
	24	* limitations under the License.
8f6c56a5	25	*
2d21ac55	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
1c79356b A	27	*/
	28	/*
	29	* @OSF_COPYRIGHT@
	30	*/
	31	/*
	32	* Mach Operating System
	33	* Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
	34	* All Rights Reserved.
	35	*
	36	* Permission to use, copy, modify and distribute this software and its
	37	* documentation is hereby granted, provided that both the copyright
	38	* notice and this permission notice appear in all copies of the
	39	* software, derivative works or modified versions, and any portions
	40	* thereof, and that both notices appear in supporting documentation.
	41	*
	42	* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
	43	* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
	44	* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
	45	*
	46	* Carnegie Mellon requests users of this software to return to
	47	*
	48	* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
	49	* School of Computer Science
	50	* Carnegie Mellon University
	51	* Pittsburgh PA 15213-3890
	52	*
	53	* any improvements or extensions that they make and grant Carnegie Mellon
	54	* the rights to redistribute these changes.
	55	*/
	56	/*
	57	*/
	58
1c79356b A	59	#include <mach/boolean.h>
	60	#include <mach/thread_switch.h>
	61	#include <ipc/ipc_port.h>
	62	#include <ipc/ipc_space.h>
	63	#include <kern/counters.h>
1c79356b A	64	#include <kern/ipc_kobject.h>
	65	#include <kern/processor.h>
	66	#include <kern/sched.h>
	67	#include <kern/sched_prim.h>
	68	#include <kern/spl.h>
	69	#include <kern/task.h>
	70	#include <kern/thread.h>
1c79356b A	71	#include <mach/policy.h>
	72
	73	#include <kern/syscall_subr.h>
	74	#include <mach/mach_host_server.h>
	75	#include <mach/mach_syscalls.h>
	76
1c79356b A	77	/*
	78	* swtch and swtch_pri both attempt to context switch (logic in
	79	* thread_block no-ops the context switch if nothing would happen).
	80	* A boolean is returned that indicates whether there is anything
	81	* else runnable.
	82	*
	83	* This boolean can be used by a thread waiting on a
	84	* lock or condition: If FALSE is returned, the thread is justified
	85	* in becoming a resource hog by continuing to spin because there's
	86	* nothing else useful that the processor could do. If TRUE is
	87	* returned, the thread should make one more check on the
	88	* lock and then be a good citizen and really suspend.
	89	*/
	90
91447636	91	static void
0b4e3aa0	92	swtch_continue(void)
1c79356b	93	{
0b4e3aa0 A	94	register processor_t myprocessor;
0b4e3aa0 A	95	boolean_t result;
1c79356b	96
91447636	97	disable_preemption();
1c79356b	98	myprocessor = current_processor();
2d21ac55	99	result = myprocessor->runq.count > 0 \|\| rt_runq.count > 0;
91447636	100	enable_preemption();
1c79356b	101
0b4e3aa0 A	102	thread_syscall_return(result);
	103	/NOTREACHED/
	104	}
1c79356b A	105
1c79356b A	106	boolean_t
91447636 A	107	swtch(
91447636 A	108	__unused struct swtch_args *args)
1c79356b A	109	{
	110	register processor_t myprocessor;
	111	boolean_t result;
	112
91447636	113	disable_preemption();
1c79356b	114	myprocessor = current_processor();
2d21ac55	115	if (myprocessor->runq.count == 0 && rt_runq.count == 0) {
1c79356b A	116	mp_enable_preemption();
	117
	118	return (FALSE);
	119	}
91447636	120	enable_preemption();
1c79356b A	121
	122	counter(c_swtch_block++);
	123
91447636	124	thread_block_reason((thread_continue_t)swtch_continue, NULL, AST_YIELD);
1c79356b	125
91447636	126	disable_preemption();
1c79356b	127	myprocessor = current_processor();
2d21ac55	128	result = myprocessor->runq.count > 0 \|\| rt_runq.count > 0;
91447636	129	enable_preemption();
1c79356b A	130
	131	return (result);
	132	}
	133
91447636	134	static void
0b4e3aa0 A	135	swtch_pri_continue(void)
	136	{
	137	register processor_t myprocessor;
	138	boolean_t result;
	139
91447636	140	thread_depress_abort_internal(current_thread());
0b4e3aa0	141
91447636	142	disable_preemption();
0b4e3aa0	143	myprocessor = current_processor();
2d21ac55	144	result = myprocessor->runq.count > 0 \|\| rt_runq.count > 0;
0b4e3aa0 A	145	mp_enable_preemption();
	146
	147	thread_syscall_return(result);
	148	/NOTREACHED/
	149	}
	150
1c79356b A	151	boolean_t
1c79356b A	152	swtch_pri(
91447636	153	__unused struct swtch_pri_args *args)
1c79356b	154	{
1c79356b A	155	register processor_t myprocessor;
1c79356b A	156	boolean_t result;
1c79356b	157
91447636	158	disable_preemption();
1c79356b	159	myprocessor = current_processor();
2d21ac55	160	if (myprocessor->runq.count == 0 && rt_runq.count == 0) {
0b4e3aa0	161	mp_enable_preemption();
1c79356b A	162
	163	return (FALSE);
	164	}
91447636	165	enable_preemption();
0b4e3aa0 A	166
	167	counter(c_swtch_pri_block++);
	168
91447636	169	thread_depress_abstime(std_quantum);
1c79356b	170
91447636	171	thread_block_reason((thread_continue_t)swtch_pri_continue, NULL, AST_YIELD);
1c79356b	172
91447636	173	thread_depress_abort_internal(current_thread());
1c79356b	174
91447636	175	disable_preemption();
1c79356b	176	myprocessor = current_processor();
2d21ac55	177	result = myprocessor->runq.count > 0 \|\| rt_runq.count > 0;
91447636	178	enable_preemption();
1c79356b A	179
	180	return (result);
	181	}
	182
91447636 A	183	static void
	184	thread_switch_continue(void)
	185	{
	186	register thread_t self = current_thread();
	187	int option = self->saved.swtch.option;
	188
	189	if (option == SWITCH_OPTION_DEPRESS)
	190	thread_depress_abort_internal(self);
	191
	192	thread_syscall_return(KERN_SUCCESS);
	193	/NOTREACHED/
	194	}
	195
1c79356b A	196	/*
	197	* thread_switch:
	198	*
	199	* Context switch. User may supply thread hint.
	200	*/
	201	kern_return_t
	202	thread_switch(
91447636	203	struct thread_switch_args *args)
1c79356b	204	{
91447636 A	205	register thread_t thread, self = current_thread();
	206	mach_port_name_t thread_name = args->thread_name;
	207	int option = args->option;
	208	mach_msg_timeout_t option_time = args->option_time;
1c79356b A	209
	210	/*
	211	* Process option.
	212	*/
	213	switch (option) {
	214
	215	case SWITCH_OPTION_NONE:
	216	case SWITCH_OPTION_DEPRESS:
	217	case SWITCH_OPTION_WAIT:
	218	break;
	219
	220	default:
	221	return (KERN_INVALID_ARGUMENT);
	222	}
	223
91447636 A	224	/*
	225	* Translate the port name if supplied.
	226	*/
1c79356b A	227	if (thread_name != MACH_PORT_NULL) {
	228	ipc_port_t port;
	229
91447636	230	if (ipc_port_translate_send(self->task->itk_space,
1c79356b A	231	thread_name, &port) == KERN_SUCCESS) {
	232	ip_reference(port);
	233	ip_unlock(port);
	234
91447636	235	thread = convert_port_to_thread(port);
1c79356b	236	ipc_port_release(port);
91447636 A	237
91447636 A	238	if (thread == self) {
2d21ac55	239	(void)thread_deallocate_internal(thread);
91447636 A	240	thread = THREAD_NULL;
91447636 A	241	}
1c79356b	242	}
91447636 A	243	else
91447636 A	244	thread = THREAD_NULL;
1c79356b	245	}
91447636 A	246	else
	247	thread = THREAD_NULL;
	248
	249	/*
	250	* Try to handoff if supplied.
	251	*/
	252	if (thread != THREAD_NULL) {
	253	processor_t processor;
	254	spl_t s;
	255
	256	s = splsched();
	257	thread_lock(thread);
	258
	259	/*
2d21ac55 A	260	* Check that the thread is not bound
	261	* to a different processor, and that realtime
	262	* is not involved.
91447636 A	263	*
	264	* Next, pull it off its run queue. If it
	265	* doesn't come, it's not eligible.
	266	*/
	267	processor = current_processor();
	268	if (processor->current_pri < BASEPRI_RTQUEUES &&
	269	thread->sched_pri < BASEPRI_RTQUEUES &&
91447636 A	270	(thread->bound_processor == PROCESSOR_NULL \|\|
91447636 A	271	thread->bound_processor == processor) &&
2d21ac55	272	run_queue_remove(thread) ) {
91447636 A	273	/*
	274	* Hah, got it!!
	275	*/
	276	thread_unlock(thread);
	277
2d21ac55	278	(void)thread_deallocate_internal(thread);
91447636 A	279
	280	if (option == SWITCH_OPTION_WAIT)
	281	assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE,
	282	option_time, 1000*NSEC_PER_USEC);
	283	else
	284	if (option == SWITCH_OPTION_DEPRESS)
	285	thread_depress_ms(option_time);
	286
	287	self->saved.swtch.option = option;
	288
	289	thread_run(self, (thread_continue_t)thread_switch_continue, NULL, thread);
	290	/* NOTREACHED */
	291	}
	292
	293	thread_unlock(thread);
	294	splx(s);
	295
	296	thread_deallocate(thread);
	297	}
	298
	299	if (option == SWITCH_OPTION_WAIT)
	300	assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE, option_time, 1000*NSEC_PER_USEC);
	301	else
	302	if (option == SWITCH_OPTION_DEPRESS)
	303	thread_depress_ms(option_time);
	304
	305	self->saved.swtch.option = option;
	306
	307	thread_block_reason((thread_continue_t)thread_switch_continue, NULL, AST_YIELD);
	308
	309	if (option == SWITCH_OPTION_DEPRESS)
	310	thread_depress_abort_internal(self);
	311
	312	return (KERN_SUCCESS);
	313	}
1c79356b	314
91447636 A	315	/*
	316	* Depress thread's priority to lowest possible for the specified interval,
	317	* with a value of zero resulting in no timeout being scheduled.
	318	*/
	319	void
	320	thread_depress_abstime(
	321	uint64_t interval)
	322	{
	323	register thread_t self = current_thread();
	324	uint64_t deadline;
	325	spl_t s;
	326
	327	s = splsched();
	328	thread_lock(self);
	329	if (!(self->sched_mode & TH_MODE_ISDEPRESSED)) {
	330	processor_t myprocessor = self->last_processor;
	331
	332	self->sched_pri = DEPRESSPRI;
	333	myprocessor->current_pri = self->sched_pri;
91447636 A	334	self->sched_mode \|= TH_MODE_DEPRESS;
	335
	336	if (interval != 0) {
	337	clock_absolutetime_interval_to_deadline(interval, &deadline);
	338	if (!timer_call_enter(&self->depress_timer, deadline))
	339	self->depress_timer_active++;
	340	}
	341	}
	342	thread_unlock(self);
	343	splx(s);
	344	}
	345
	346	void
	347	thread_depress_ms(
	348	mach_msg_timeout_t interval)
	349	{
	350	uint64_t abstime;
	351
	352	clock_interval_to_absolutetime_interval(
	353	interval, 1000*NSEC_PER_USEC, &abstime);
	354	thread_depress_abstime(abstime);
	355	}
	356
	357	/*
	358	* Priority depression expiration.
	359	*/
	360	void
	361	thread_depress_expire(
	362	void *p0,
	363	__unused void *p1)
	364	{
	365	thread_t thread = p0;
	366	spl_t s;
	367
	368	s = splsched();
	369	thread_lock(thread);
	370	if (--thread->depress_timer_active == 0) {
	371	thread->sched_mode &= ~TH_MODE_ISDEPRESSED;
	372	compute_priority(thread, FALSE);
	373	}
	374	thread_unlock(thread);
	375	splx(s);
	376	}
	377
	378	/*
	379	* Prematurely abort priority depression if there is one.
	380	*/
	381	kern_return_t
	382	thread_depress_abort_internal(
	383	thread_t thread)
	384	{
	385	kern_return_t result = KERN_NOT_DEPRESSED;
	386	spl_t s;
	387
	388	s = splsched();
	389	thread_lock(thread);
	390	if (!(thread->sched_mode & TH_MODE_POLLDEPRESS)) {
	391	if (thread->sched_mode & TH_MODE_ISDEPRESSED) {
	392	thread->sched_mode &= ~TH_MODE_ISDEPRESSED;
	393	compute_priority(thread, FALSE);
	394	result = KERN_SUCCESS;
	395	}
	396
	397	if (timer_call_cancel(&thread->depress_timer))
398	thread->depress_timer_active--;
399	}
400	thread_unlock(thread);
401	splx(s);
402
403	return (result);
404	}
405
406	void
407	thread_poll_yield(
408	thread_t self)
409	{
410	spl_t s;
411
412	assert(self == current_thread());
413
414	s = splsched();
415	if (!(self->sched_mode & (TH_MODE_REALTIME\|TH_MODE_TIMESHARE))) {
416	uint64_t total_computation, abstime;
417
418	abstime = mach_absolute_time();
419	total_computation = abstime - self->computation_epoch;
420	total_computation += self->computation_metered;
421	if (total_computation >= max_poll_computation) {
422	processor_t myprocessor = current_processor();
423	ast_t preempt;
424
425	thread_lock(self);
426	if (!(self->sched_mode & TH_MODE_ISDEPRESSED)) {
427	self->sched_pri = DEPRESSPRI;
428	myprocessor->current_pri = self->sched_pri;
91447636 A	429	}
	430	self->computation_epoch = abstime;
	431	self->computation_metered = 0;
	432	self->sched_mode \|= TH_MODE_POLLDEPRESS;
	433
	434	abstime += (total_computation >> sched_poll_yield_shift);
	435	if (!timer_call_enter(&self->depress_timer, abstime))
	436	self->depress_timer_active++;
	437	thread_unlock(self);
	438
c910b4d9	439	if ((preempt = csw_check(myprocessor)) != AST_NONE)
91447636 A	440	ast_on(preempt);
	441	}
	442	}
	443	splx(s);
1c79356b	444	}
2d21ac55 A	445
	446
	447	void
	448	thread_yield_internal(
	449	mach_msg_timeout_t ms)
	450	{
	451	processor_t myprocessor;
	452
	453	disable_preemption();
	454	myprocessor = current_processor();
	455	if (myprocessor->runq.count == 0 && rt_runq.count == 0) {
	456	mp_enable_preemption();
	457
	458	return;
	459	}
	460	enable_preemption();
	461
	462	thread_depress_ms(ms);
	463
	464	thread_block_reason(THREAD_CONTINUE_NULL, NULL, AST_YIELD);
	465
	466	thread_depress_abort_internal(current_thread());
	467	}
	468