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

/*
 * Copyright (c) 2000-2004 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
 * under the License.
 * 
 * @APPLE_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					||
				myprocessor->processor_set->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				&&
			myprocessor->processor_set->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					||
				myprocessor->processor_set->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					||
				myprocessor->processor_set->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					&&
			myprocessor->processor_set->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						||
				myprocessor->processor_set->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) {
				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 if the thread is in the right pset,
		 *	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->processor_set == processor->processor_set	&&
			(thread->bound_processor == PROCESSOR_NULL	||
			 thread->bound_processor == processor)				&&
			run_queue_remove(thread) != RUN_QUEUE_NULL			) {
			/*
			 *	Hah, got it!!
			 */
			thread_unlock(thread);

			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_PREEMPT;
		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->sched_mode &= ~TH_MODE_PREEMPT;
			}
			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(self, myprocessor)) != AST_NONE)
				ast_on(preempt);
		}
	}
	splx(s);
}
Commit	Line	Data
1c79356b	1	/*
91447636	2	* Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
1c79356b A	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
37839358 A	6	* The contents of this file constitute Original Code as defined in and
	7	* are subject to the Apple Public Source License Version 1.1 (the
	8	* "License"). You may not use this file except in compliance with the
	9	* License. Please obtain a copy of the License at
	10	* http://www.apple.com/publicsource and read it before using this file.
e5568f75	11	*
37839358 A	12	* This Original Code and all software distributed under the License are
37839358 A	13	* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
1c79356b A	14	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
1c79356b A	15	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
37839358 A	16	* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
	17	* License for the specific language governing rights and limitations
	18	* under the License.
1c79356b A	19	*
	20	* @APPLE_LICENSE_HEADER_END@
	21	*/
	22	/*
	23	* @OSF_COPYRIGHT@
	24	*/
	25	/*
	26	* Mach Operating System
	27	* Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
	28	* All Rights Reserved.
	29	*
	30	* Permission to use, copy, modify and distribute this software and its
	31	* documentation is hereby granted, provided that both the copyright
	32	* notice and this permission notice appear in all copies of the
	33	* software, derivative works or modified versions, and any portions
	34	* thereof, and that both notices appear in supporting documentation.
	35	*
	36	* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
	37	* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
	38	* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
	39	*
	40	* Carnegie Mellon requests users of this software to return to
	41	*
	42	* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
	43	* School of Computer Science
	44	* Carnegie Mellon University
	45	* Pittsburgh PA 15213-3890
	46	*
	47	* any improvements or extensions that they make and grant Carnegie Mellon
	48	* the rights to redistribute these changes.
	49	*/
	50	/*
	51	*/
	52
1c79356b A	53	#include <mach/boolean.h>
	54	#include <mach/thread_switch.h>
	55	#include <ipc/ipc_port.h>
	56	#include <ipc/ipc_space.h>
	57	#include <kern/counters.h>
1c79356b A	58	#include <kern/ipc_kobject.h>
	59	#include <kern/processor.h>
	60	#include <kern/sched.h>
	61	#include <kern/sched_prim.h>
	62	#include <kern/spl.h>
	63	#include <kern/task.h>
	64	#include <kern/thread.h>
1c79356b A	65	#include <mach/policy.h>
	66
	67	#include <kern/syscall_subr.h>
	68	#include <mach/mach_host_server.h>
	69	#include <mach/mach_syscalls.h>
	70
1c79356b A	71	/*
	72	* swtch and swtch_pri both attempt to context switch (logic in
	73	* thread_block no-ops the context switch if nothing would happen).
	74	* A boolean is returned that indicates whether there is anything
	75	* else runnable.
	76	*
	77	* This boolean can be used by a thread waiting on a
	78	* lock or condition: If FALSE is returned, the thread is justified
	79	* in becoming a resource hog by continuing to spin because there's
	80	* nothing else useful that the processor could do. If TRUE is
	81	* returned, the thread should make one more check on the
	82	* lock and then be a good citizen and really suspend.
	83	*/
	84
91447636	85	static void
0b4e3aa0	86	swtch_continue(void)
1c79356b	87	{
0b4e3aa0 A	88	register processor_t myprocessor;
0b4e3aa0 A	89	boolean_t result;
1c79356b	90
91447636	91	disable_preemption();
1c79356b	92	myprocessor = current_processor();
0b4e3aa0 A	93	result = myprocessor->runq.count > 0 \|\|
0b4e3aa0 A	94	myprocessor->processor_set->runq.count > 0;
91447636	95	enable_preemption();
1c79356b	96
0b4e3aa0 A	97	thread_syscall_return(result);
	98	/NOTREACHED/
	99	}
1c79356b A	100
1c79356b A	101	boolean_t
91447636 A	102	swtch(
91447636 A	103	__unused struct swtch_args *args)
1c79356b A	104	{
	105	register processor_t myprocessor;
	106	boolean_t result;
	107
91447636	108	disable_preemption();
1c79356b	109	myprocessor = current_processor();
0b4e3aa0	110	if ( myprocessor->runq.count == 0 &&
1c79356b A	111	myprocessor->processor_set->runq.count == 0 ) {
	112	mp_enable_preemption();
	113
	114	return (FALSE);
	115	}
91447636	116	enable_preemption();
1c79356b A	117
	118	counter(c_swtch_block++);
	119
91447636	120	thread_block_reason((thread_continue_t)swtch_continue, NULL, AST_YIELD);
1c79356b	121
91447636	122	disable_preemption();
1c79356b	123	myprocessor = current_processor();
0b4e3aa0 A	124	result = myprocessor->runq.count > 0 \|\|
0b4e3aa0 A	125	myprocessor->processor_set->runq.count > 0;
91447636	126	enable_preemption();
1c79356b A	127
	128	return (result);
	129	}
	130
91447636	131	static void
0b4e3aa0 A	132	swtch_pri_continue(void)
	133	{
	134	register processor_t myprocessor;
	135	boolean_t result;
	136
91447636	137	thread_depress_abort_internal(current_thread());
0b4e3aa0	138
91447636	139	disable_preemption();
0b4e3aa0 A	140	myprocessor = current_processor();
	141	result = myprocessor->runq.count > 0 \|\|
	142	myprocessor->processor_set->runq.count > 0;
	143	mp_enable_preemption();
	144
	145	thread_syscall_return(result);
	146	/NOTREACHED/
	147	}
	148
1c79356b A	149	boolean_t
1c79356b A	150	swtch_pri(
91447636	151	__unused struct swtch_pri_args *args)
1c79356b	152	{
1c79356b A	153	register processor_t myprocessor;
1c79356b A	154	boolean_t result;
1c79356b	155
91447636	156	disable_preemption();
1c79356b	157	myprocessor = current_processor();
0b4e3aa0	158	if ( myprocessor->runq.count == 0 &&
1c79356b	159	myprocessor->processor_set->runq.count == 0 ) {
0b4e3aa0	160	mp_enable_preemption();
1c79356b A	161
	162	return (FALSE);
	163	}
91447636	164	enable_preemption();
0b4e3aa0 A	165
	166	counter(c_swtch_pri_block++);
	167
91447636	168	thread_depress_abstime(std_quantum);
1c79356b	169
91447636	170	thread_block_reason((thread_continue_t)swtch_pri_continue, NULL, AST_YIELD);
1c79356b	171
91447636	172	thread_depress_abort_internal(current_thread());
1c79356b	173
91447636	174	disable_preemption();
1c79356b	175	myprocessor = current_processor();
0b4e3aa0 A	176	result = myprocessor->runq.count > 0 \|\|
0b4e3aa0 A	177	myprocessor->processor_set->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
	238	if (thread == self) {
	239	thread_deallocate_internal(thread);
	240	thread = THREAD_NULL;
	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	/*
	260	* Check if the thread is in the right pset,
	261	* is not bound to a different processor,
	262	* and that realtime is not involved.
	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 &&
	270	thread->processor_set == processor->processor_set &&
	271	(thread->bound_processor == PROCESSOR_NULL \|\|
	272	thread->bound_processor == processor) &&
	273	run_queue_remove(thread) != RUN_QUEUE_NULL ) {
	274	/*
	275	* Hah, got it!!
	276	*/
	277	thread_unlock(thread);
	278
	279	thread_deallocate_internal(thread);
	280
	281	if (option == SWITCH_OPTION_WAIT)
	282	assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE,
	283	option_time, 1000*NSEC_PER_USEC);
	284	else
	285	if (option == SWITCH_OPTION_DEPRESS)
	286	thread_depress_ms(option_time);
	287
	288	self->saved.swtch.option = option;
	289
	290	thread_run(self, (thread_continue_t)thread_switch_continue, NULL, thread);
	291	/* NOTREACHED */
	292	}
	293
	294	thread_unlock(thread);
	295	splx(s);
	296
	297	thread_deallocate(thread);
	298	}
	299
	300	if (option == SWITCH_OPTION_WAIT)
	301	assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE, option_time, 1000*NSEC_PER_USEC);
	302	else
	303	if (option == SWITCH_OPTION_DEPRESS)
	304	thread_depress_ms(option_time);
	305
	306	self->saved.swtch.option = option;
	307
	308	thread_block_reason((thread_continue_t)thread_switch_continue, NULL, AST_YIELD);
	309
310	if (option == SWITCH_OPTION_DEPRESS)
311	thread_depress_abort_internal(self);
312
313	return (KERN_SUCCESS);
314	}
1c79356b	315
91447636 A	316	/*
	317	* Depress thread's priority to lowest possible for the specified interval,
	318	* with a value of zero resulting in no timeout being scheduled.
	319	*/
	320	void
	321	thread_depress_abstime(
	322	uint64_t interval)
	323	{
	324	register thread_t self = current_thread();
	325	uint64_t deadline;
	326	spl_t s;
	327
	328	s = splsched();
	329	thread_lock(self);
	330	if (!(self->sched_mode & TH_MODE_ISDEPRESSED)) {
	331	processor_t myprocessor = self->last_processor;
	332
	333	self->sched_pri = DEPRESSPRI;
	334	myprocessor->current_pri = self->sched_pri;
	335	self->sched_mode &= ~TH_MODE_PREEMPT;
	336	self->sched_mode \|= TH_MODE_DEPRESS;
	337
	338	if (interval != 0) {
	339	clock_absolutetime_interval_to_deadline(interval, &deadline);
	340	if (!timer_call_enter(&self->depress_timer, deadline))
	341	self->depress_timer_active++;
	342	}
	343	}
	344	thread_unlock(self);
	345	splx(s);
	346	}
	347
	348	void
	349	thread_depress_ms(
	350	mach_msg_timeout_t interval)
	351	{
	352	uint64_t abstime;
	353
	354	clock_interval_to_absolutetime_interval(
	355	interval, 1000*NSEC_PER_USEC, &abstime);
	356	thread_depress_abstime(abstime);
	357	}
	358
	359	/*
	360	* Priority depression expiration.
	361	*/
	362	void
	363	thread_depress_expire(
	364	void *p0,
	365	__unused void *p1)
	366	{
	367	thread_t thread = p0;
	368	spl_t s;
	369
	370	s = splsched();
	371	thread_lock(thread);
	372	if (--thread->depress_timer_active == 0) {
	373	thread->sched_mode &= ~TH_MODE_ISDEPRESSED;
	374	compute_priority(thread, FALSE);
	375	}
	376	thread_unlock(thread);
	377	splx(s);
	378	}
	379
380	/*
381	* Prematurely abort priority depression if there is one.
382	*/
383	kern_return_t
384	thread_depress_abort_internal(
385	thread_t thread)
386	{
387	kern_return_t result = KERN_NOT_DEPRESSED;
388	spl_t s;
389
390	s = splsched();
391	thread_lock(thread);
392	if (!(thread->sched_mode & TH_MODE_POLLDEPRESS)) {
393	if (thread->sched_mode & TH_MODE_ISDEPRESSED) {
394	thread->sched_mode &= ~TH_MODE_ISDEPRESSED;
395	compute_priority(thread, FALSE);
396	result = KERN_SUCCESS;
397	}
398
399	if (timer_call_cancel(&thread->depress_timer))
400	thread->depress_timer_active--;
401	}
402	thread_unlock(thread);
403	splx(s);
404
405	return (result);
406	}
407
408	void
409	thread_poll_yield(
410	thread_t self)
411	{
412	spl_t s;
413
414	assert(self == current_thread());
415
416	s = splsched();
417	if (!(self->sched_mode & (TH_MODE_REALTIME\|TH_MODE_TIMESHARE))) {
418	uint64_t total_computation, abstime;
419
420	abstime = mach_absolute_time();
421	total_computation = abstime - self->computation_epoch;
422	total_computation += self->computation_metered;
423	if (total_computation >= max_poll_computation) {
424	processor_t myprocessor = current_processor();
425	ast_t preempt;
426
427	thread_lock(self);
428	if (!(self->sched_mode & TH_MODE_ISDEPRESSED)) {
429	self->sched_pri = DEPRESSPRI;
430	myprocessor->current_pri = self->sched_pri;
431	self->sched_mode &= ~TH_MODE_PREEMPT;
432	}
433	self->computation_epoch = abstime;
434	self->computation_metered = 0;
435	self->sched_mode \|= TH_MODE_POLLDEPRESS;
436
437	abstime += (total_computation >> sched_poll_yield_shift);
438	if (!timer_call_enter(&self->depress_timer, abstime))
439	self->depress_timer_active++;
440	thread_unlock(self);
441
442	if ((preempt = csw_check(self, myprocessor)) != AST_NONE)
443	ast_on(preempt);
444	}
445	}
446	splx(s);
1c79356b	447	}