WebSVN – HelenOS-historic – Diff – /kernel/trunk/generic/src/proc/scheduler.c


/*
 * Copyright (C) 2001-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */
 
/** @addtogroup genericproc
 * @{
 */
 
/**
 * @file
 * @brief   Scheduler and load balancing.
 *
 * This file contains the scheduler and kcpulb kernel thread which
 * performs load-balancing of per-CPU run queues.
 */
 
#include <proc/scheduler.h>
#include <proc/thread.h>
#include <proc/task.h>
#include <mm/frame.h>
#include <mm/page.h>
#include <mm/as.h>
#include <time/delay.h>
#include <arch/asm.h>
#include <arch/faddr.h>
#include <atomic.h>
#include <synch/spinlock.h>
#include <config.h>
#include <context.h>
#include <func.h>
#include <arch.h>
#include <adt/list.h>
#include <panic.h>
#include <typedefs.h>
#include <cpu.h>
#include <print.h>
#include <debug.h>
 
static void before_task_runs(void);
static void before_thread_runs(void);
static void after_thread_ran(void);
static void scheduler_separated_stack(void);
 
atomic_t nrdy;  /**< Number of ready threads in the system. */
 
/** Carry out actions before new task runs. */
void before_task_runs(void)
{
    before_task_runs_arch();
}
 
/** Take actions before new thread runs.
 *
 * Perform actions that need to be
 * taken before the newly selected
 * tread is passed control.
 *
 * THREAD->lock is locked on entry
 *
 */
void before_thread_runs(void)
{
    before_thread_runs_arch();
#ifdef CONFIG_FPU_LAZY
    if(THREAD==CPU->fpu_owner)
        fpu_enable();
    else
        fpu_disable();
#else
    fpu_enable();
    if (THREAD->fpu_context_exists)
        fpu_context_restore(THREAD->saved_fpu_context);
    else {
        fpu_init();
        THREAD->fpu_context_exists=1;
    }
#endif
}
 
/** Take actions after THREAD had run.
 *
 * Perform actions that need to be
 * taken after the running thread
 * had been preempted by the scheduler.
 *
 * THREAD->lock is locked on entry
 *
 */
void after_thread_ran(void)
{
    after_thread_ran_arch();
}
 
#ifdef CONFIG_FPU_LAZY
void scheduler_fpu_lazy_request(void)
{
restart:
    fpu_enable();
    spinlock_lock(&CPU->lock);
 
    /* Save old context */
    if (CPU->fpu_owner != NULL) {  
        spinlock_lock(&CPU->fpu_owner->lock);
        fpu_context_save(CPU->fpu_owner->saved_fpu_context);
        /* don't prevent migration */
        CPU->fpu_owner->fpu_context_engaged=0;
        spinlock_unlock(&CPU->fpu_owner->lock);
        CPU->fpu_owner = NULL;
    }
 
    spinlock_lock(&THREAD->lock);
    if (THREAD->fpu_context_exists) {
        fpu_context_restore(THREAD->saved_fpu_context);
    } else {
        /* Allocate FPU context */
        if (!THREAD->saved_fpu_context) {
            /* Might sleep */
            spinlock_unlock(&THREAD->lock);
            spinlock_unlock(&CPU->lock);
            THREAD->saved_fpu_context = slab_alloc(fpu_context_slab,
                                   0);
            /* We may have switched CPUs during slab_alloc */
            goto restart;
        }
        fpu_init();
        THREAD->fpu_context_exists=1;
    }
    CPU->fpu_owner=THREAD;
    THREAD->fpu_context_engaged = 1;
    spinlock_unlock(&THREAD->lock);
 
    spinlock_unlock(&CPU->lock);
}
#endif
 
/** Initialize scheduler
 *
 * Initialize kernel scheduler.
 *
 */
void scheduler_init(void)
{
}
 
/** Get thread to be scheduled
 *
 * Get the optimal thread to be scheduled
 * according to thread accounting and scheduler
 * policy.
 *
 * @return Thread to be scheduled.
 *
 */
static thread_t *find_best_thread(void)
{
    thread_t *t;
    runq_t *r;
    int i;
 
    ASSERT(CPU != NULL);
 
loop:
    interrupts_enable();
   
    if (atomic_get(&CPU->nrdy) == 0) {
        /*
         * For there was nothing to run, the CPU goes to sleep
         * until a hardware interrupt or an IPI comes.
         * This improves energy saving and hyperthreading.
         */
 
        /*
         * An interrupt might occur right now and wake up a thread.
         * In such case, the CPU will continue to go to sleep
         * even though there is a runnable thread.
         */
 
         cpu_sleep();
         goto loop;
    }
 
    interrupts_disable();
   
    for (i = 0; i<RQ_COUNT; i++) {
        r = &CPU->rq[i];
        spinlock_lock(&r->lock);
        if (r->n == 0) {
            /*
             * If this queue is empty, try a lower-priority queue.
             */
            spinlock_unlock(&r->lock);
            continue;
        }
 
        atomic_dec(&CPU->nrdy);
        atomic_dec(&nrdy);
        r->n--;
 
        /*
         * Take the first thread from the queue.
         */
        t = list_get_instance(r->rq_head.next, thread_t, rq_link);
        list_remove(&t->rq_link);
 
        spinlock_unlock(&r->lock);
 
        spinlock_lock(&t->lock);
        t->cpu = CPU;
 
        t->ticks = us2ticks((i+1)*10000);
        t->priority = i;    /* correct rq index */
 
        /*
         * Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge.
         */
        t->flags &= ~X_STOLEN;
        spinlock_unlock(&t->lock);
 
        return t;
    }
    goto loop;
 
}
 
/** Prevent rq starvation
 *
 * Prevent low priority threads from starving in rq's.
 *
 * When the function decides to relink rq's, it reconnects
 * respective pointers so that in result threads with 'pri'
 * greater or equal start are moved to a higher-priority queue.
 *
 * @param start Threshold priority.
 *
 */
static void relink_rq(int start)
{
    link_t head;
    runq_t *r;
    int i, n;
 
    list_initialize(&head);
    spinlock_lock(&CPU->lock);
    if (CPU->needs_relink > NEEDS_RELINK_MAX) {
        for (i = start; i<RQ_COUNT-1; i++) {
            /* remember and empty rq[i + 1] */
            r = &CPU->rq[i + 1];
            spinlock_lock(&r->lock);
            list_concat(&head, &r->rq_head);
            n = r->n;
            r->n = 0;
            spinlock_unlock(&r->lock);
       
            /* append rq[i + 1] to rq[i] */
            r = &CPU->rq[i];
            spinlock_lock(&r->lock);
            list_concat(&r->rq_head, &head);
            r->n += n;
            spinlock_unlock(&r->lock);
        }
        CPU->needs_relink = 0;
    }
    spinlock_unlock(&CPU->lock);
 
}
 
/** The scheduler
 *
 * The thread scheduling procedure.
 * Passes control directly to
 * scheduler_separated_stack().
 *
 */
void scheduler(void)
{
    volatile ipl_t ipl;
 
    ASSERT(CPU != NULL);
 
    ipl = interrupts_disable();
 
    if (atomic_get(&haltstate))
        halt();
   
    if (THREAD) {
        spinlock_lock(&THREAD->lock);
#ifndef CONFIG_FPU_LAZY
        fpu_context_save(THREAD->saved_fpu_context);
#endif
        if (!context_save(&THREAD->saved_context)) {
            /*
             * This is the place where threads leave scheduler();
             */
            spinlock_unlock(&THREAD->lock);
            interrupts_restore(THREAD->saved_context.ipl);
           
            return;
        }
 
        /*
         * Interrupt priority level of preempted thread is recorded here
         * to facilitate scheduler() invocations from interrupts_disable()'d
         * code (e.g. waitq_sleep_timeout()).
         */
        THREAD->saved_context.ipl = ipl;
    }
 
    /*
     * Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM
     * and preemption counter. At this point THE could be coming either
     * from THREAD's or CPU's stack.
     */
    the_copy(THE, (the_t *) CPU->stack);
 
    /*
     * We may not keep the old stack.
     * Reason: If we kept the old stack and got blocked, for instance, in
     * find_best_thread(), the old thread could get rescheduled by another
     * CPU and overwrite the part of its own stack that was also used by
     * the scheduler on this CPU.
     *
     * Moreover, we have to bypass the compiler-generated POP sequence
     * which is fooled by SP being set to the very top of the stack.
     * Therefore the scheduler() function continues in
     * scheduler_separated_stack().
     */
    context_save(&CPU->saved_context);
    context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (uintptr_t) CPU->stack, CPU_STACK_SIZE);
    context_restore(&CPU->saved_context);
    /* not reached */
}
 
/** Scheduler stack switch wrapper
 *
 * Second part of the scheduler() function
 * using new stack. Handling the actual context
 * switch to a new thread.
 *
 * Assume THREAD->lock is held.
 */
void scheduler_separated_stack(void)
{
    int priority;
   
    ASSERT(CPU != NULL);
   
    if (THREAD) {
        /* must be run after the switch to scheduler stack */
        after_thread_ran();
 
        switch (THREAD->state) {
            case Running:
            spinlock_unlock(&THREAD->lock);
            thread_ready(THREAD);
            break;
 
            case Exiting:
repeat:
                if (THREAD->detached) {
                thread_destroy(THREAD);
            } else {
                /*
                 * The thread structure is kept allocated until somebody
                 * calls thread_detach() on it.
                 */
                if (!spinlock_trylock(&THREAD->join_wq.lock)) {
                    /*
                     * Avoid deadlock.
                     */
                    spinlock_unlock(&THREAD->lock);
                    delay(10);
                    spinlock_lock(&THREAD->lock);
                    goto repeat;
                }
                _waitq_wakeup_unsafe(&THREAD->join_wq, false);
                spinlock_unlock(&THREAD->join_wq.lock);
               
                THREAD->state = Undead;
                spinlock_unlock(&THREAD->lock);
            }
            break;
           
            case Sleeping:
            /*
             * Prefer the thread after it's woken up.
             */
            THREAD->priority = -1;
 
            /*
             * We need to release wq->lock which we locked in waitq_sleep().
             * Address of wq->lock is kept in THREAD->sleep_queue.
             */
            spinlock_unlock(&THREAD->sleep_queue->lock);
 
            /*
             * Check for possible requests for out-of-context invocation.
             */
            if (THREAD->call_me) {
                THREAD->call_me(THREAD->call_me_with);
                THREAD->call_me = NULL;
                THREAD->call_me_with = NULL;
            }
 
            spinlock_unlock(&THREAD->lock);
 
            break;
 
            default:
            /*
             * Entering state is unexpected.
             */
            panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]);
            break;
        }
 
        THREAD = NULL;
    }
 
    THREAD = find_best_thread();
   
    spinlock_lock(&THREAD->lock);
    priority = THREAD->priority;
    spinlock_unlock(&THREAD->lock);
 
    relink_rq(priority);       
 
    /*
     * If both the old and the new task are the same, lots of work is avoided.
     */
    if (TASK != THREAD->task) {
        as_t *as1 = NULL;
        as_t *as2;
 
        if (TASK) {
            spinlock_lock(&TASK->lock);
            as1 = TASK->as;
            spinlock_unlock(&TASK->lock);
        }
 
        spinlock_lock(&THREAD->task->lock);
        as2 = THREAD->task->as;
        spinlock_unlock(&THREAD->task->lock);
       
        /*
         * Note that it is possible for two tasks to share one address space.
         */
        if (as1 != as2) {
            /*
             * Both tasks and address spaces are different.
             * Replace the old one with the new one.
             */
            as_switch(as1, as2);
        }
        TASK = THREAD->task;
        before_task_runs();
    }
 
    spinlock_lock(&THREAD->lock);  
    THREAD->state = Running;
 
#ifdef SCHEDULER_VERBOSE
    printf("cpu%d: tid %d (priority=%d,ticks=%lld,nrdy=%ld)\n", CPU->id, THREAD->tid, THREAD->priority, THREAD->ticks, atomic_get(&CPU->nrdy));
#endif  
 
    /*
     * Some architectures provide late kernel PA2KA(identity)
     * mapping in a page fault handler. However, the page fault
     * handler uses the kernel stack of the running thread and
     * therefore cannot be used to map it. The kernel stack, if
     * necessary, is to be mapped in before_thread_runs(). This
     * function must be executed before the switch to the new stack.
     */
    before_thread_runs();
 
    /*
     * Copy the knowledge of CPU, TASK, THREAD and preemption counter to thread's stack.
     */
    the_copy(THE, (the_t *) THREAD->kstack);
   
    context_restore(&THREAD->saved_context);
    /* not reached */
}
 
#ifdef CONFIG_SMP
/** Load balancing thread
 *
 * SMP load balancing thread, supervising thread supplies
 * for the CPU it's wired to.
 *
 * @param arg Generic thread argument (unused).
 *
 */
void kcpulb(void *arg)
{
    thread_t *t;
    int count, average, i, j, k = 0;
    ipl_t ipl;
 
    /*
     * Detach kcpulb as nobody will call thread_join_timeout() on it.
     */
    thread_detach(THREAD);
   
loop:
    /*
     * Work in 1s intervals.
     */
    thread_sleep(1);
 
not_satisfied:
    /*
     * Calculate the number of threads that will be migrated/stolen from
     * other CPU's. Note that situation can have changed between two
     * passes. Each time get the most up to date counts.
     */
    average = atomic_get(&nrdy) / config.cpu_active + 1;
    count = average - atomic_get(&CPU->nrdy);
 
    if (count <= 0)
        goto satisfied;
 
    /*
     * Searching least priority queues on all CPU's first and most priority queues on all CPU's last.
     */
    for (j=RQ_COUNT-1; j >= 0; j--) {
        for (i=0; i < config.cpu_active; i++) {
            link_t *l;
            runq_t *r;
            cpu_t *cpu;
 
            cpu = &cpus[(i + k) % config.cpu_active];
 
            /*
             * Not interested in ourselves.
             * Doesn't require interrupt disabling for kcpulb is X_WIRED.
             */
            if (CPU == cpu)
                continue;
            if (atomic_get(&cpu->nrdy) <= average)
                continue;
 
            ipl = interrupts_disable();
            r = &cpu->rq[j];
            spinlock_lock(&r->lock);
            if (r->n == 0) {
                spinlock_unlock(&r->lock);
                interrupts_restore(ipl);
                continue;
            }
       
            t = NULL;
            l = r->rq_head.prev;    /* search rq from the back */
            while (l != &r->rq_head) {
                t = list_get_instance(l, thread_t, rq_link);
                /*
                 * We don't want to steal CPU-wired threads neither threads already stolen.
                 * The latter prevents threads from migrating between CPU's without ever being run.
                 * We don't want to steal threads whose FPU context is still in CPU.
                 */
                spinlock_lock(&t->lock);
                if ( (!(t->flags & (X_WIRED | X_STOLEN))) && (!(t->fpu_context_engaged)) ) {
                    /*
                     * Remove t from r.
                     */
                    spinlock_unlock(&t->lock);
                   
                    atomic_dec(&cpu->nrdy);
                    atomic_dec(&nrdy);
 
                    r->n--;
                    list_remove(&t->rq_link);
 
                    break;
                }
                spinlock_unlock(&t->lock);
                l = l->prev;
                t = NULL;
            }
            spinlock_unlock(&r->lock);
 
            if (t) {
                /*
                 * Ready t on local CPU
                 */
                spinlock_lock(&t->lock);
#ifdef KCPULB_VERBOSE
                printf("kcpulb%d: TID %d -> cpu%d, nrdy=%ld, avg=%nd\n", CPU->id, t->tid, CPU->id, atomic_get(&CPU->nrdy), atomic_get(&nrdy) / config.cpu_active);
#endif
                t->flags |= X_STOLEN;
                t->state = Entering;
                spinlock_unlock(&t->lock);
   
                thread_ready(t);
 
                interrupts_restore(ipl);
   
                if (--count == 0)
                    goto satisfied;
                   
                /*
                 * We are not satisfied yet, focus on another CPU next time.
                 */
                k++;
               
                continue;
            }
            interrupts_restore(ipl);
        }
    }
 
    if (atomic_get(&CPU->nrdy)) {
        /*
         * Be a little bit light-weight and let migrated threads run.
         */
        scheduler();
    } else {
        /*
         * We failed to migrate a single thread.
         * Give up this turn.
         */
        goto loop;
    }
       
    goto not_satisfied;
 
satisfied:
    goto loop;
}
 
#endif /* CONFIG_SMP */
 
 
/** Print information about threads & scheduler queues */
void sched_print_list(void)
{
    ipl_t ipl;
    int cpu,i;
    runq_t *r;
    thread_t *t;
    link_t *cur;
 
    /* We are going to mess with scheduler structures,
     * let's not be interrupted */
    ipl = interrupts_disable();
    for (cpu=0;cpu < config.cpu_count; cpu++) {
 
        if (!cpus[cpu].active)
            continue;
 
        spinlock_lock(&cpus[cpu].lock);
        printf("cpu%d: address=%p, nrdy=%ld, needs_relink=%ld\n",
               cpus[cpu].id, &cpus[cpu], atomic_get(&cpus[cpu].nrdy), cpus[cpu].needs_relink);
       
        for (i=0; i<RQ_COUNT; i++) {
            r = &cpus[cpu].rq[i];
            spinlock_lock(&r->lock);
            if (!r->n) {
                spinlock_unlock(&r->lock);
                continue;
            }
            printf("\trq[%d]: ", i);
            for (cur=r->rq_head.next; cur!=&r->rq_head; cur=cur->next) {
                t = list_get_instance(cur, thread_t, rq_link);
                printf("%d(%s) ", t->tid,
                       thread_states[t->state]);
            }
            printf("\n");
            spinlock_unlock(&r->lock);
        }
        spinlock_unlock(&cpus[cpu].lock);
    }
   
    interrupts_restore(ipl);
}
 
/** @}
 */
 

Rev 1757	Rev 1780
1	/*	1	/*
2	* Copyright (C) 2001-2004 Jakub Jermar	2	* Copyright (C) 2001-2004 Jakub Jermar
3	* All rights reserved.	3	* All rights reserved.
4	*	4	*
5	* Redistribution and use in source and binary forms, with or without	5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions	6	* modification, are permitted provided that the following conditions
7	* are met:	7	* are met:
8	*	8	*
9	* - Redistributions of source code must retain the above copyright	9	* - Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.	10	* notice, this list of conditions and the following disclaimer.
11	* - Redistributions in binary form must reproduce the above copyright	11	* - Redistributions in binary form must reproduce the above copyright
12	* notice, this list of conditions and the following disclaimer in the	12	* notice, this list of conditions and the following disclaimer in the
13	* documentation and/or other materials provided with the distribution.	13	* documentation and/or other materials provided with the distribution.
14	* - The name of the author may not be used to endorse or promote products	14	* - The name of the author may not be used to endorse or promote products
15	* derived from this software without specific prior written permission.	15	* derived from this software without specific prior written permission.
16	*	16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR	17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES	18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.	19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,	20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT	21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,	22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY	23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF	25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27	*/	27	*/
28		28
29	/** @addtogroup genericproc	29	/** @addtogroup genericproc
30	* @{	30	* @{
31	*/	31	*/
32		32
33	/**	33	/**
34	* @file	34	* @file
35	* @brief Scheduler and load balancing.	35	* @brief Scheduler and load balancing.
36	*	36	*
37	* This file contains the scheduler and kcpulb kernel thread which	37	* This file contains the scheduler and kcpulb kernel thread which
38	* performs load-balancing of per-CPU run queues.	38	* performs load-balancing of per-CPU run queues.
39	*/	39	*/
40		40
41	#include <proc/scheduler.h>	41	#include <proc/scheduler.h>
42	#include <proc/thread.h>	42	#include <proc/thread.h>
43	#include <proc/task.h>	43	#include <proc/task.h>
44	#include <mm/frame.h>	44	#include <mm/frame.h>
45	#include <mm/page.h>	45	#include <mm/page.h>
46	#include <mm/as.h>	46	#include <mm/as.h>
47	#include <time/delay.h>	47	#include <time/delay.h>
48	#include <arch/asm.h>	48	#include <arch/asm.h>
49	#include <arch/faddr.h>	49	#include <arch/faddr.h>
50	#include <atomic.h>	50	#include <atomic.h>
51	#include <synch/spinlock.h>	51	#include <synch/spinlock.h>
52	#include <config.h>	52	#include <config.h>
53	#include <context.h>	53	#include <context.h>
54	#include <func.h>	54	#include <func.h>
55	#include <arch.h>	55	#include <arch.h>
56	#include <adt/list.h>	56	#include <adt/list.h>
57	#include <panic.h>	57	#include <panic.h>
58	#include <typedefs.h>	58	#include <typedefs.h>
59	#include <cpu.h>	59	#include <cpu.h>
60	#include <print.h>	60	#include <print.h>
61	#include <debug.h>	61	#include <debug.h>
62		62
63	static void before_task_runs(void);	63	static void before_task_runs(void);
64	static void before_thread_runs(void);	64	static void before_thread_runs(void);
65	static void after_thread_ran(void);	65	static void after_thread_ran(void);
66	static void scheduler_separated_stack(void);	66	static void scheduler_separated_stack(void);
67		67
68	atomic_t nrdy; /*< Number of ready threads in the system. /	68	atomic_t nrdy; /*< Number of ready threads in the system. /
69		69
70	/** Carry out actions before new task runs. */	70	/** Carry out actions before new task runs. */
71	void before_task_runs(void)	71	void before_task_runs(void)
72	{	72	{
73	before_task_runs_arch();	73	before_task_runs_arch();
74	}	74	}
75		75
76	/** Take actions before new thread runs.	76	/** Take actions before new thread runs.
77	*	77	*
78	* Perform actions that need to be	78	* Perform actions that need to be
79	* taken before the newly selected	79	* taken before the newly selected
80	* tread is passed control.	80	* tread is passed control.
81	*	81	*
82	* THREAD->lock is locked on entry	82	* THREAD->lock is locked on entry
83	*	83	*
84	*/	84	*/
85	void before_thread_runs(void)	85	void before_thread_runs(void)
86	{	86	{
87	before_thread_runs_arch();	87	before_thread_runs_arch();
88	#ifdef CONFIG_FPU_LAZY	88	#ifdef CONFIG_FPU_LAZY
89	if(THREAD==CPU->fpu_owner)	89	if(THREAD==CPU->fpu_owner)
90	fpu_enable();	90	fpu_enable();
91	else	91	else
92	fpu_disable();	92	fpu_disable();
93	#else	93	#else
94	fpu_enable();	94	fpu_enable();
95	if (THREAD->fpu_context_exists)	95	if (THREAD->fpu_context_exists)
96	fpu_context_restore(THREAD->saved_fpu_context);	96	fpu_context_restore(THREAD->saved_fpu_context);
97	else {	97	else {
98	fpu_init();	98	fpu_init();
99	THREAD->fpu_context_exists=1;	99	THREAD->fpu_context_exists=1;
100	}	100	}
101	#endif	101	#endif
102	}	102	}
103		103
104	/** Take actions after THREAD had run.	104	/** Take actions after THREAD had run.
105	*	105	*
106	* Perform actions that need to be	106	* Perform actions that need to be
107	* taken after the running thread	107	* taken after the running thread
108	* had been preempted by the scheduler.	108	* had been preempted by the scheduler.
109	*	109	*
110	* THREAD->lock is locked on entry	110	* THREAD->lock is locked on entry
111	*	111	*
112	*/	112	*/
113	void after_thread_ran(void)	113	void after_thread_ran(void)
114	{	114	{
115	after_thread_ran_arch();	115	after_thread_ran_arch();
116	}	116	}
117		117
118	#ifdef CONFIG_FPU_LAZY	118	#ifdef CONFIG_FPU_LAZY
119	void scheduler_fpu_lazy_request(void)	119	void scheduler_fpu_lazy_request(void)
120	{	120	{
121	restart:	121	restart:
122	fpu_enable();	122	fpu_enable();
123	spinlock_lock(&CPU->lock);	123	spinlock_lock(&CPU->lock);
124		124
125	/* Save old context */	125	/* Save old context */
126	if (CPU->fpu_owner != NULL) {	126	if (CPU->fpu_owner != NULL) {
127	spinlock_lock(&CPU->fpu_owner->lock);	127	spinlock_lock(&CPU->fpu_owner->lock);
128	fpu_context_save(CPU->fpu_owner->saved_fpu_context);	128	fpu_context_save(CPU->fpu_owner->saved_fpu_context);
129	/* don't prevent migration */	129	/* don't prevent migration */
130	CPU->fpu_owner->fpu_context_engaged=0;	130	CPU->fpu_owner->fpu_context_engaged=0;
131	spinlock_unlock(&CPU->fpu_owner->lock);	131	spinlock_unlock(&CPU->fpu_owner->lock);
132	CPU->fpu_owner = NULL;	132	CPU->fpu_owner = NULL;
133	}	133	}
134		134
135	spinlock_lock(&THREAD->lock);	135	spinlock_lock(&THREAD->lock);
136	if (THREAD->fpu_context_exists) {	136	if (THREAD->fpu_context_exists) {
137	fpu_context_restore(THREAD->saved_fpu_context);	137	fpu_context_restore(THREAD->saved_fpu_context);
138	} else {	138	} else {
139	/* Allocate FPU context */	139	/* Allocate FPU context */
140	if (!THREAD->saved_fpu_context) {	140	if (!THREAD->saved_fpu_context) {
141	/* Might sleep */	141	/* Might sleep */
142	spinlock_unlock(&THREAD->lock);	142	spinlock_unlock(&THREAD->lock);
143	spinlock_unlock(&CPU->lock);	143	spinlock_unlock(&CPU->lock);
144	THREAD->saved_fpu_context = slab_alloc(fpu_context_slab,	144	THREAD->saved_fpu_context = slab_alloc(fpu_context_slab,
145	0);	145	0);
146	/* We may have switched CPUs during slab_alloc */	146	/* We may have switched CPUs during slab_alloc */
147	goto restart;	147	goto restart;
148	}	148	}
149	fpu_init();	149	fpu_init();
150	THREAD->fpu_context_exists=1;	150	THREAD->fpu_context_exists=1;
151	}	151	}
152	CPU->fpu_owner=THREAD;	152	CPU->fpu_owner=THREAD;
153	THREAD->fpu_context_engaged = 1;	153	THREAD->fpu_context_engaged = 1;
154	spinlock_unlock(&THREAD->lock);	154	spinlock_unlock(&THREAD->lock);
155		155
156	spinlock_unlock(&CPU->lock);	156	spinlock_unlock(&CPU->lock);
157	}	157	}
158	#endif	158	#endif
159		159
160	/** Initialize scheduler	160	/** Initialize scheduler
161	*	161	*
162	* Initialize kernel scheduler.	162	* Initialize kernel scheduler.
163	*	163	*
164	*/	164	*/
165	void scheduler_init(void)	165	void scheduler_init(void)
166	{	166	{
167	}	167	}
168		168
169	/** Get thread to be scheduled	169	/** Get thread to be scheduled
170	*	170	*
171	* Get the optimal thread to be scheduled	171	* Get the optimal thread to be scheduled
172	* according to thread accounting and scheduler	172	* according to thread accounting and scheduler
173	* policy.	173	* policy.
174	*	174	*
175	* @return Thread to be scheduled.	175	* @return Thread to be scheduled.
176	*	176	*
177	*/	177	*/
178	static thread_t *find_best_thread(void)	178	static thread_t *find_best_thread(void)
179	{	179	{
180	thread_t *t;	180	thread_t *t;
181	runq_t *r;	181	runq_t *r;
182	int i;	182	int i;
183		183
184	ASSERT(CPU != NULL);	184	ASSERT(CPU != NULL);
185		185
186	loop:	186	loop:
187	interrupts_enable();	187	interrupts_enable();
188		188
189	if (atomic_get(&CPU->nrdy) == 0) {	189	if (atomic_get(&CPU->nrdy) == 0) {
190	/*	190	/*
191	* For there was nothing to run, the CPU goes to sleep	191	* For there was nothing to run, the CPU goes to sleep
192	* until a hardware interrupt or an IPI comes.	192	* until a hardware interrupt or an IPI comes.
193	* This improves energy saving and hyperthreading.	193	* This improves energy saving and hyperthreading.
194	*/	194	*/
195		195
196	/*	196	/*
197	* An interrupt might occur right now and wake up a thread.	197	* An interrupt might occur right now and wake up a thread.
198	* In such case, the CPU will continue to go to sleep	198	* In such case, the CPU will continue to go to sleep
199	* even though there is a runnable thread.	199	* even though there is a runnable thread.
200	*/	200	*/
201		201
202	cpu_sleep();	202	cpu_sleep();
203	goto loop;	203	goto loop;
204	}	204	}
205		205
206	interrupts_disable();	206	interrupts_disable();
207		207
208	for (i = 0; i<RQ_COUNT; i++) {	208	for (i = 0; i<RQ_COUNT; i++) {
209	r = &CPU->rq[i];	209	r = &CPU->rq[i];
210	spinlock_lock(&r->lock);	210	spinlock_lock(&r->lock);
211	if (r->n == 0) {	211	if (r->n == 0) {
212	/*	212	/*
213	* If this queue is empty, try a lower-priority queue.	213	* If this queue is empty, try a lower-priority queue.
214	*/	214	*/
215	spinlock_unlock(&r->lock);	215	spinlock_unlock(&r->lock);
216	continue;	216	continue;
217	}	217	}
218		218
219	atomic_dec(&CPU->nrdy);	219	atomic_dec(&CPU->nrdy);
220	atomic_dec(&nrdy);	220	atomic_dec(&nrdy);
221	r->n--;	221	r->n--;
222		222
223	/*	223	/*
224	* Take the first thread from the queue.	224	* Take the first thread from the queue.
225	*/	225	*/
226	t = list_get_instance(r->rq_head.next, thread_t, rq_link);	226	t = list_get_instance(r->rq_head.next, thread_t, rq_link);
227	list_remove(&t->rq_link);	227	list_remove(&t->rq_link);
228		228
229	spinlock_unlock(&r->lock);	229	spinlock_unlock(&r->lock);
230		230
231	spinlock_lock(&t->lock);	231	spinlock_lock(&t->lock);
232	t->cpu = CPU;	232	t->cpu = CPU;
233		233
234	t->ticks = us2ticks((i+1)*10000);	234	t->ticks = us2ticks((i+1)*10000);
235	t->priority = i; /* correct rq index */	235	t->priority = i; /* correct rq index */
236		236
237	/*	237	/*
238	* Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge.	238	* Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge.
239	*/	239	*/
240	t->flags &= ~X_STOLEN;	240	t->flags &= ~X_STOLEN;
241	spinlock_unlock(&t->lock);	241	spinlock_unlock(&t->lock);
242		242
243	return t;	243	return t;
244	}	244	}
245	goto loop;	245	goto loop;
246		246
247	}	247	}
248		248
249	/** Prevent rq starvation	249	/** Prevent rq starvation
250	*	250	*
251	* Prevent low priority threads from starving in rq's.	251	* Prevent low priority threads from starving in rq's.
252	*	252	*
253	* When the function decides to relink rq's, it reconnects	253	* When the function decides to relink rq's, it reconnects
254	* respective pointers so that in result threads with 'pri'	254	* respective pointers so that in result threads with 'pri'
255	* greater or equal start are moved to a higher-priority queue.	255	* greater or equal start are moved to a higher-priority queue.
256	*	256	*
257	* @param start Threshold priority.	257	* @param start Threshold priority.
258	*	258	*
259	*/	259	*/
260	static void relink_rq(int start)	260	static void relink_rq(int start)
261	{	261	{
262	link_t head;	262	link_t head;
263	runq_t *r;	263	runq_t *r;
264	int i, n;	264	int i, n;
265		265
266	list_initialize(&head);	266	list_initialize(&head);
267	spinlock_lock(&CPU->lock);	267	spinlock_lock(&CPU->lock);
268	if (CPU->needs_relink > NEEDS_RELINK_MAX) {	268	if (CPU->needs_relink > NEEDS_RELINK_MAX) {
269	for (i = start; i<RQ_COUNT-1; i++) {	269	for (i = start; i<RQ_COUNT-1; i++) {
270	/* remember and empty rq[i + 1] */	270	/* remember and empty rq[i + 1] */
271	r = &CPU->rq[i + 1];	271	r = &CPU->rq[i + 1];
272	spinlock_lock(&r->lock);	272	spinlock_lock(&r->lock);
273	list_concat(&head, &r->rq_head);	273	list_concat(&head, &r->rq_head);
274	n = r->n;	274	n = r->n;
275	r->n = 0;	275	r->n = 0;
276	spinlock_unlock(&r->lock);	276	spinlock_unlock(&r->lock);
277		277
278	/* append rq[i + 1] to rq[i] */	278	/* append rq[i + 1] to rq[i] */
279	r = &CPU->rq[i];	279	r = &CPU->rq[i];
280	spinlock_lock(&r->lock);	280	spinlock_lock(&r->lock);
281	list_concat(&r->rq_head, &head);	281	list_concat(&r->rq_head, &head);
282	r->n += n;	282	r->n += n;
283	spinlock_unlock(&r->lock);	283	spinlock_unlock(&r->lock);
284	}	284	}
285	CPU->needs_relink = 0;	285	CPU->needs_relink = 0;
286	}	286	}
287	spinlock_unlock(&CPU->lock);	287	spinlock_unlock(&CPU->lock);
288		288
289	}	289	}
290		290
291	/** The scheduler	291	/** The scheduler
292	*	292	*
293	* The thread scheduling procedure.	293	* The thread scheduling procedure.
294	* Passes control directly to	294	* Passes control directly to
295	* scheduler_separated_stack().	295	* scheduler_separated_stack().
296	*	296	*
297	*/	297	*/
298	void scheduler(void)	298	void scheduler(void)
299	{	299	{
300	volatile ipl_t ipl;	300	volatile ipl_t ipl;
301		301
302	ASSERT(CPU != NULL);	302	ASSERT(CPU != NULL);
303		303
304	ipl = interrupts_disable();	304	ipl = interrupts_disable();
305		305
306	if (atomic_get(&haltstate))	306	if (atomic_get(&haltstate))
307	halt();	307	halt();
308		308
309	if (THREAD) {	309	if (THREAD) {
310	spinlock_lock(&THREAD->lock);	310	spinlock_lock(&THREAD->lock);
311	#ifndef CONFIG_FPU_LAZY	311	#ifndef CONFIG_FPU_LAZY
312	fpu_context_save(THREAD->saved_fpu_context);	312	fpu_context_save(THREAD->saved_fpu_context);
313	#endif	313	#endif
314	if (!context_save(&THREAD->saved_context)) {	314	if (!context_save(&THREAD->saved_context)) {
315	/*	315	/*
316	* This is the place where threads leave scheduler();	316	* This is the place where threads leave scheduler();
317	*/	317	*/
318	spinlock_unlock(&THREAD->lock);	318	spinlock_unlock(&THREAD->lock);
319	interrupts_restore(THREAD->saved_context.ipl);	319	interrupts_restore(THREAD->saved_context.ipl);
320		320
321	return;	321	return;
322	}	322	}
323		323
324	/*	324	/*
325	* Interrupt priority level of preempted thread is recorded here	325	* Interrupt priority level of preempted thread is recorded here
326	* to facilitate scheduler() invocations from interrupts_disable()'d	326	* to facilitate scheduler() invocations from interrupts_disable()'d
327	* code (e.g. waitq_sleep_timeout()).	327	* code (e.g. waitq_sleep_timeout()).
328	*/	328	*/
329	THREAD->saved_context.ipl = ipl;	329	THREAD->saved_context.ipl = ipl;
330	}	330	}
331		331
332	/*	332	/*
333	* Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM	333	* Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM
334	* and preemption counter. At this point THE could be coming either	334	* and preemption counter. At this point THE could be coming either
335	* from THREAD's or CPU's stack.	335	* from THREAD's or CPU's stack.
336	*/	336	*/
337	the_copy(THE, (the_t *) CPU->stack);	337	the_copy(THE, (the_t *) CPU->stack);
338		338
339	/*	339	/*
340	* We may not keep the old stack.	340	* We may not keep the old stack.
341	* Reason: If we kept the old stack and got blocked, for instance, in	341	* Reason: If we kept the old stack and got blocked, for instance, in
342	* find_best_thread(), the old thread could get rescheduled by another	342	* find_best_thread(), the old thread could get rescheduled by another
343	* CPU and overwrite the part of its own stack that was also used by	343	* CPU and overwrite the part of its own stack that was also used by
344	* the scheduler on this CPU.	344	* the scheduler on this CPU.
345	*	345	*
346	* Moreover, we have to bypass the compiler-generated POP sequence	346	* Moreover, we have to bypass the compiler-generated POP sequence
347	* which is fooled by SP being set to the very top of the stack.	347	* which is fooled by SP being set to the very top of the stack.
348	* Therefore the scheduler() function continues in	348	* Therefore the scheduler() function continues in
349	* scheduler_separated_stack().	349	* scheduler_separated_stack().
350	*/	350	*/
351	context_save(&CPU->saved_context);	351	context_save(&CPU->saved_context);
352	context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (__address) CPU->stack, CPU_STACK_SIZE);	352	context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (uintptr_t) CPU->stack, CPU_STACK_SIZE);
353	context_restore(&CPU->saved_context);	353	context_restore(&CPU->saved_context);
354	/* not reached */	354	/* not reached */
355	}	355	}
356		356
357	/** Scheduler stack switch wrapper	357	/** Scheduler stack switch wrapper
358	*	358	*
359	* Second part of the scheduler() function	359	* Second part of the scheduler() function
360	* using new stack. Handling the actual context	360	* using new stack. Handling the actual context
361	* switch to a new thread.	361	* switch to a new thread.
362	*	362	*
363	* Assume THREAD->lock is held.	363	* Assume THREAD->lock is held.
364	*/	364	*/
365	void scheduler_separated_stack(void)	365	void scheduler_separated_stack(void)
366	{	366	{
367	int priority;	367	int priority;
368		368
369	ASSERT(CPU != NULL);	369	ASSERT(CPU != NULL);
370		370
371	if (THREAD) {	371	if (THREAD) {
372	/* must be run after the switch to scheduler stack */	372	/* must be run after the switch to scheduler stack */
373	after_thread_ran();	373	after_thread_ran();
374		374
375	switch (THREAD->state) {	375	switch (THREAD->state) {
376	case Running:	376	case Running:
377	spinlock_unlock(&THREAD->lock);	377	spinlock_unlock(&THREAD->lock);
378	thread_ready(THREAD);	378	thread_ready(THREAD);
379	break;	379	break;
380		380
381	case Exiting:	381	case Exiting:
382	repeat:	382	repeat:
383	if (THREAD->detached) {	383	if (THREAD->detached) {
384	thread_destroy(THREAD);	384	thread_destroy(THREAD);
385	} else {	385	} else {
386	/*	386	/*
387	* The thread structure is kept allocated until somebody	387	* The thread structure is kept allocated until somebody
388	* calls thread_detach() on it.	388	* calls thread_detach() on it.
389	*/	389	*/
390	if (!spinlock_trylock(&THREAD->join_wq.lock)) {	390	if (!spinlock_trylock(&THREAD->join_wq.lock)) {
391	/*	391	/*
392	* Avoid deadlock.	392	* Avoid deadlock.
393	*/	393	*/
394	spinlock_unlock(&THREAD->lock);	394	spinlock_unlock(&THREAD->lock);
395	delay(10);	395	delay(10);
396	spinlock_lock(&THREAD->lock);	396	spinlock_lock(&THREAD->lock);
397	goto repeat;	397	goto repeat;
398	}	398	}
399	_waitq_wakeup_unsafe(&THREAD->join_wq, false);	399	_waitq_wakeup_unsafe(&THREAD->join_wq, false);
400	spinlock_unlock(&THREAD->join_wq.lock);	400	spinlock_unlock(&THREAD->join_wq.lock);
401		401
402	THREAD->state = Undead;	402	THREAD->state = Undead;
403	spinlock_unlock(&THREAD->lock);	403	spinlock_unlock(&THREAD->lock);
404	}	404	}
405	break;	405	break;
406		406
407	case Sleeping:	407	case Sleeping:
408	/*	408	/*
409	* Prefer the thread after it's woken up.	409	* Prefer the thread after it's woken up.
410	*/	410	*/
411	THREAD->priority = -1;	411	THREAD->priority = -1;
412		412
413	/*	413	/*
414	* We need to release wq->lock which we locked in waitq_sleep().	414	* We need to release wq->lock which we locked in waitq_sleep().
415	* Address of wq->lock is kept in THREAD->sleep_queue.	415	* Address of wq->lock is kept in THREAD->sleep_queue.
416	*/	416	*/
417	spinlock_unlock(&THREAD->sleep_queue->lock);	417	spinlock_unlock(&THREAD->sleep_queue->lock);
418		418
419	/*	419	/*
420	* Check for possible requests for out-of-context invocation.	420	* Check for possible requests for out-of-context invocation.
421	*/	421	*/
422	if (THREAD->call_me) {	422	if (THREAD->call_me) {
423	THREAD->call_me(THREAD->call_me_with);	423	THREAD->call_me(THREAD->call_me_with);
424	THREAD->call_me = NULL;	424	THREAD->call_me = NULL;
425	THREAD->call_me_with = NULL;	425	THREAD->call_me_with = NULL;
426	}	426	}
427		427
428	spinlock_unlock(&THREAD->lock);	428	spinlock_unlock(&THREAD->lock);
429		429
430	break;	430	break;
431		431
432	default:	432	default:
433	/*	433	/*
434	* Entering state is unexpected.	434	* Entering state is unexpected.
435	*/	435	*/
436	panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]);	436	panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]);
437	break;	437	break;
438	}	438	}
439		439
440	THREAD = NULL;	440	THREAD = NULL;
441	}	441	}
442		442
443	THREAD = find_best_thread();	443	THREAD = find_best_thread();
444		444
445	spinlock_lock(&THREAD->lock);	445	spinlock_lock(&THREAD->lock);
446	priority = THREAD->priority;	446	priority = THREAD->priority;
447	spinlock_unlock(&THREAD->lock);	447	spinlock_unlock(&THREAD->lock);
448		448
449	relink_rq(priority);	449	relink_rq(priority);
450		450
451	/*	451	/*
452	* If both the old and the new task are the same, lots of work is avoided.	452	* If both the old and the new task are the same, lots of work is avoided.
453	*/	453	*/
454	if (TASK != THREAD->task) {	454	if (TASK != THREAD->task) {
455	as_t *as1 = NULL;	455	as_t *as1 = NULL;
456	as_t *as2;	456	as_t *as2;
457		457
458	if (TASK) {	458	if (TASK) {
459	spinlock_lock(&TASK->lock);	459	spinlock_lock(&TASK->lock);
460	as1 = TASK->as;	460	as1 = TASK->as;
461	spinlock_unlock(&TASK->lock);	461	spinlock_unlock(&TASK->lock);
462	}	462	}
463		463
464	spinlock_lock(&THREAD->task->lock);	464	spinlock_lock(&THREAD->task->lock);
465	as2 = THREAD->task->as;	465	as2 = THREAD->task->as;
466	spinlock_unlock(&THREAD->task->lock);	466	spinlock_unlock(&THREAD->task->lock);
467		467
468	/*	468	/*
469	* Note that it is possible for two tasks to share one address space.	469	* Note that it is possible for two tasks to share one address space.
470	*/	470	*/
471	if (as1 != as2) {	471	if (as1 != as2) {
472	/*	472	/*
473	* Both tasks and address spaces are different.	473	* Both tasks and address spaces are different.
474	* Replace the old one with the new one.	474	* Replace the old one with the new one.
475	*/	475	*/
476	as_switch(as1, as2);	476	as_switch(as1, as2);
477	}	477	}
478	TASK = THREAD->task;	478	TASK = THREAD->task;
479	before_task_runs();	479	before_task_runs();
480	}	480	}
481		481
482	spinlock_lock(&THREAD->lock);	482	spinlock_lock(&THREAD->lock);
483	THREAD->state = Running;	483	THREAD->state = Running;
484		484
485	#ifdef SCHEDULER_VERBOSE	485	#ifdef SCHEDULER_VERBOSE
486	printf("cpu%d: tid %d (priority=%d,ticks=%lld,nrdy=%ld)\n", CPU->id, THREAD->tid, THREAD->priority, THREAD->ticks, atomic_get(&CPU->nrdy));	486	printf("cpu%d: tid %d (priority=%d,ticks=%lld,nrdy=%ld)\n", CPU->id, THREAD->tid, THREAD->priority, THREAD->ticks, atomic_get(&CPU->nrdy));
487	#endif	487	#endif
488		488
489	/*	489	/*
490	* Some architectures provide late kernel PA2KA(identity)	490	* Some architectures provide late kernel PA2KA(identity)
491	* mapping in a page fault handler. However, the page fault	491	* mapping in a page fault handler. However, the page fault
492	* handler uses the kernel stack of the running thread and	492	* handler uses the kernel stack of the running thread and
493	* therefore cannot be used to map it. The kernel stack, if	493	* therefore cannot be used to map it. The kernel stack, if
494	* necessary, is to be mapped in before_thread_runs(). This	494	* necessary, is to be mapped in before_thread_runs(). This
495	* function must be executed before the switch to the new stack.	495	* function must be executed before the switch to the new stack.
496	*/	496	*/
497	before_thread_runs();	497	before_thread_runs();
498		498
499	/*	499	/*
500	* Copy the knowledge of CPU, TASK, THREAD and preemption counter to thread's stack.	500	* Copy the knowledge of CPU, TASK, THREAD and preemption counter to thread's stack.

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(root)/kernel/trunk/generic/src/proc/scheduler.c – Rev 1757 → 1780