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NetBSD/lib/libpthread/pthread_run.c

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/* $NetBSD: pthread_run.c,v 1.12 2003/09/16 13:51:35 cl Exp $ */
/*-
* Copyright (c) 2001 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Nathan J. Williams.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: pthread_run.c,v 1.12 2003/09/16 13:51:35 cl Exp $");
#include <ucontext.h>
#include "pthread.h"
#include "pthread_int.h"
#ifdef PTHREAD_RUN_DEBUG
#define SDPRINTF(x) DPRINTF(x)
#else
#define SDPRINTF(x)
#endif
extern pthread_spin_t pthread__runqueue_lock;
extern struct pthread_queue_t pthread__runqueue;
extern struct pthread_queue_t pthread__idlequeue;
extern pthread_spin_t pthread__deadqueue_lock;
extern struct pthread_queue_t pthread__reidlequeue;
__strong_alias(__libc_thr_yield,sched_yield)
int
sched_yield(void)
{
pthread_t self, next;
extern int pthread__started;
if (pthread__started) {
self = pthread__self();
SDPRINTF(("(sched_yield %p) yielding\n", self));
pthread_spinlock(self, &pthread__runqueue_lock);
self->pt_state = PT_STATE_RUNNABLE;
PTQ_INSERT_TAIL(&pthread__runqueue, self, pt_runq);
/*
* There will always be at least one thread on the runqueue,
* because we just put ourselves there.
*/
next = PTQ_FIRST(&pthread__runqueue);
PTQ_REMOVE(&pthread__runqueue, next, pt_runq);
next->pt_state = PT_STATE_RUNNING;
if (next != self)
pthread__locked_switch(self, next,
&pthread__runqueue_lock);
else
pthread_spinunlock(self, &pthread__runqueue_lock);
}
return 0;
}
/* Go do another thread, without putting us on the run queue. */
void
pthread__block(pthread_t self, pthread_spin_t *queuelock)
{
pthread_t next;
next = pthread__next(self);
next->pt_state = PT_STATE_RUNNING;
SDPRINTF(("(calling locked_switch %p, %p) spinlock %d, %d\n",
self, next, self->pt_spinlocks, next->pt_spinlocks));
pthread__locked_switch(self, next, queuelock);
SDPRINTF(("(back from locked_switch %p, %p) spinlock %d, %d\n",
self, next, self->pt_spinlocks, next->pt_spinlocks));
}
/* Get the next thread to switch to. Will never return NULL. */
pthread_t
pthread__next(pthread_t self)
{
pthread_t next;
pthread_spinlock(self, &pthread__runqueue_lock);
next = PTQ_FIRST(&pthread__runqueue);
if (next) {
pthread__assert(next->pt_type == PT_THREAD_NORMAL);
PTQ_REMOVE(&pthread__runqueue, next, pt_runq);
} else {
next = PTQ_FIRST(&pthread__idlequeue);
pthread__assert(next != 0);
PTQ_REMOVE(&pthread__idlequeue, next, pt_runq);
pthread__assert(next->pt_type == PT_THREAD_IDLE);
SDPRINTF(("(next %p) returning idle thread %p\n", self, next));
}
pthread_spinunlock(self, &pthread__runqueue_lock);
return next;
}
/* Put a thread back on the run queue */
void
pthread__sched(pthread_t self, pthread_t thread)
{
SDPRINTF(("(sched %p) scheduling %p\n", self, thread));
thread->pt_state = PT_STATE_RUNNABLE;
pthread__assert(thread->pt_type == PT_THREAD_NORMAL);
pthread__assert(thread->pt_spinlocks == 0);
#ifdef PTHREAD__DEBUG
thread->rescheds++;
#endif
pthread_spinlock(self, &pthread__runqueue_lock);
PTQ_INSERT_TAIL(&pthread__runqueue, thread, pt_runq);
pthread_spinunlock(self, &pthread__runqueue_lock);
}
/* Put a bunch of sleeping threads on the run queue */
void
pthread__sched_sleepers(pthread_t self, struct pthread_queue_t *threadq)
{
pthread_t thread;
pthread_spinlock(self, &pthread__runqueue_lock);
PTQ_FOREACH(thread, threadq, pt_sleep) {
SDPRINTF(("(sched_sleepers %p) scheduling %p\n", self, thread));
thread->pt_state = PT_STATE_RUNNABLE;
pthread__assert(thread->pt_type == PT_THREAD_NORMAL);
pthread__assert(thread->pt_spinlocks == 0);
#ifdef PTHREAD__DEBUG
thread->rescheds++;
#endif
PTQ_INSERT_TAIL(&pthread__runqueue, thread, pt_runq);
}
pthread_spinunlock(self, &pthread__runqueue_lock);
}
/* Make a thread a candidate idle thread. */
void
pthread__sched_idle(pthread_t self, pthread_t thread)
{
SDPRINTF(("(sched_idle %p) idling %p\n", self, thread));
thread->pt_state = PT_STATE_RUNNABLE;
thread->pt_flags &= ~PT_FLAG_IDLED;
thread->pt_trapuc = NULL;
_INITCONTEXT_U(thread->pt_uc);
thread->pt_uc->uc_stack = thread->pt_stack;
thread->pt_uc->uc_link = NULL;
makecontext(thread->pt_uc, pthread__idle, 0);
pthread_spinlock(self, &pthread__runqueue_lock);
PTQ_INSERT_TAIL(&pthread__idlequeue, thread, pt_runq);
pthread_spinunlock(self, &pthread__runqueue_lock);
}
void
pthread__sched_idle2(pthread_t self)
{
pthread_t idlethread, qhead, next;
/* XXXconcurrency: only reidle threads on same vp */
qhead = NULL;
pthread_spinlock(self, &pthread__deadqueue_lock);
idlethread = PTQ_FIRST(&pthread__reidlequeue);
while (idlethread != NULL) {
SDPRINTF(("(sched_idle2 %p) reidling %p\n", self, idlethread));
next = PTQ_NEXT(idlethread, pt_runq);
if (idlethread->pt_next == NULL) {
PTQ_REMOVE(&pthread__reidlequeue, idlethread, pt_runq);
idlethread->pt_next = qhead;
qhead = idlethread;
} else {
SDPRINTF(("(sched_idle2 %p) %p is in a preemption loop\n", self, idlethread));
}
idlethread = next;
}
pthread_spinunlock(self, &pthread__deadqueue_lock);
if (qhead)
pthread__sched_bulk(self, qhead);
}
/*
* Put a series of threads, linked by their pt_next fields, onto the
* run queue.
*/
void
pthread__sched_bulk(pthread_t self, pthread_t qhead)
{
pthread_t next;
pthread_spinlock(self, &pthread__runqueue_lock);
for ( ; qhead && (qhead != self) ; qhead = next) {
next = qhead->pt_next;
pthread__assert(qhead->pt_spinlocks == 0);
pthread__assert(qhead->pt_type != PT_THREAD_UPCALL);
if (qhead->pt_type == PT_THREAD_NORMAL) {
qhead->pt_state = PT_STATE_RUNNABLE;
qhead->pt_next = NULL;
qhead->pt_parent = NULL;
#ifdef PTHREAD__DEBUG
qhead->rescheds++;
#endif
SDPRINTF(("(bulk %p) scheduling %p\n", self, qhead));
pthread__assert(PTQ_LAST(&pthread__runqueue, pthread_queue_t) != qhead);
pthread__assert(PTQ_FIRST(&pthread__runqueue) != qhead);
PTQ_INSERT_TAIL(&pthread__runqueue, qhead, pt_runq);
} else if (qhead->pt_type == PT_THREAD_IDLE) {
qhead->pt_state = PT_STATE_RUNNABLE;
qhead->pt_flags &= ~PT_FLAG_IDLED;
qhead->pt_next = NULL;
qhead->pt_parent = NULL;
qhead->pt_trapuc = NULL;
_INITCONTEXT_U(qhead->pt_uc);
qhead->pt_uc->uc_stack = qhead->pt_stack;
qhead->pt_uc->uc_link = NULL;
makecontext(qhead->pt_uc, pthread__idle, 0);
SDPRINTF(("(bulk %p) idling %p\n", self, qhead));
PTQ_INSERT_TAIL(&pthread__idlequeue, qhead, pt_runq);
}
}
pthread_spinunlock(self, &pthread__runqueue_lock);
}
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