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1 jermar 1
/*
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 * Copyright (C) 2001-2004 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include <time/clock.h>
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#include <time/timeout.h>
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#include <arch/types.h>
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#include <config.h>
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#include <synch/spinlock.h>
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#include <synch/waitq.h>
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#include <func.h>
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#include <proc/scheduler.h>
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#include <cpu.h>
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#include <arch.h>
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#include <adt/list.h>
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#include <atomic.h>
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#include <proc/thread.h>
1 jermar 42
 
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/** Clock routine
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 *
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 * Clock routine executed from clock interrupt handler
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 * (assuming interrupts_disable()'d). Runs expired timeouts
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 * and preemptive scheduling.
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 *
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 */
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void clock(void)
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{
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	link_t *l;
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	timeout_t *h;
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	timeout_handler_t f;
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	void *arg;
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	/*
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	 * To avoid lock ordering problems,
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	 * run all expired timeouts as you visit them.
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	 */
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	spinlock_lock(&CPU->timeoutlock);
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	while ((l = CPU->timeout_active_head.next) != &CPU->timeout_active_head) {
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		h = list_get_instance(l, timeout_t, link);
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		spinlock_lock(&h->lock);
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		if (h->ticks-- != 0) {
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			spinlock_unlock(&h->lock);
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			break;
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		}
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		list_remove(l);
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		f = h->handler;
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		arg = h->arg;
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		timeout_reinitialize(h);
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		spinlock_unlock(&h->lock);	
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		spinlock_unlock(&CPU->timeoutlock);
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		f(arg);
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		spinlock_lock(&CPU->timeoutlock);
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	}
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	spinlock_unlock(&CPU->timeoutlock);
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	/*
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	 * Do CPU usage accounting and find out whether to preempt THREAD.
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	 */
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	if (THREAD) {
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		__u64 ticks;
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		spinlock_lock(&CPU->lock);
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		CPU->needs_relink++;
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		spinlock_unlock(&CPU->lock);	
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		spinlock_lock(&THREAD->lock);
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		if ((ticks = THREAD->ticks))
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			THREAD->ticks--;
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		spinlock_unlock(&THREAD->lock);
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		if (!ticks && !PREEMPTION_DISABLED) {
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			scheduler();
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		}
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	}
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}