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), (__address) 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 1705	Rev 1708
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		29
30	/** @addtogroup genericproc	30	/** @addtogroup genericproc
31	* @{	31	* @{
32	*/	32	*/
33		33
34	/**	34	/**
35	* @file	35	* @file
36	* @brief Scheduler and load balancing.	36	* @brief Scheduler and load balancing.
37	*	37	*
38	* This file contains the scheduler and kcpulb kernel thread which	38	* This file contains the scheduler and kcpulb kernel thread which
39	* performs load-balancing of per-CPU run queues.	39	* performs load-balancing of per-CPU run queues.
40	*/	40	*/
41		41
42	#include <proc/scheduler.h>	42	#include <proc/scheduler.h>
43	#include <proc/thread.h>	43	#include <proc/thread.h>
44	#include <proc/task.h>	44	#include <proc/task.h>
45	#include <mm/frame.h>	45	#include <mm/frame.h>
46	#include <mm/page.h>	46	#include <mm/page.h>
47	#include <mm/as.h>	47	#include <mm/as.h>
48	#include <time/delay.h>	48	#include <time/delay.h>
49	#include <arch/asm.h>	49	#include <arch/asm.h>
50	#include <arch/faddr.h>	50	#include <arch/faddr.h>
51	#include <atomic.h>	51	#include <atomic.h>
52	#include <synch/spinlock.h>	52	#include <synch/spinlock.h>
53	#include <config.h>	53	#include <config.h>
54	#include <context.h>	54	#include <context.h>
55	#include <func.h>	55	#include <func.h>
56	#include <arch.h>	56	#include <arch.h>
57	#include <adt/list.h>	57	#include <adt/list.h>
58	#include <panic.h>	58	#include <panic.h>
59	#include <typedefs.h>	59	#include <typedefs.h>
60	#include <cpu.h>	60	#include <cpu.h>
61	#include <print.h>	61	#include <print.h>
62	#include <debug.h>	62	#include <debug.h>
63		63
64	static void before_task_runs(void);	64	static void before_task_runs(void);
65	static void before_thread_runs(void);	65	static void before_thread_runs(void);
66	static void after_thread_ran(void);	66	static void after_thread_ran(void);
67	static void scheduler_separated_stack(void);	67	static void scheduler_separated_stack(void);
68		68
69	atomic_t nrdy; /*< Number of ready threads in the system. /	69	atomic_t nrdy; /*< Number of ready threads in the system. /
70		70
71	/** Carry out actions before new task runs. */	71	/** Carry out actions before new task runs. */
72	void before_task_runs(void)	72	void before_task_runs(void)
73	{	73	{
74	before_task_runs_arch();	74	before_task_runs_arch();
75	}	75	}
76		76
77	/** Take actions before new thread runs.	77	/** Take actions before new thread runs.
78	*	78	*
79	* Perform actions that need to be	79	* Perform actions that need to be
80	* taken before the newly selected	80	* taken before the newly selected
81	* tread is passed control.	81	* tread is passed control.
82	*	82	*
83	* THREAD->lock is locked on entry	83	* THREAD->lock is locked on entry
84	*	84	*
85	*/	85	*/
86	void before_thread_runs(void)	86	void before_thread_runs(void)
87	{	87	{
88	before_thread_runs_arch();	88	before_thread_runs_arch();
89	#ifdef CONFIG_FPU_LAZY	89	#ifdef CONFIG_FPU_LAZY
90	if(THREAD==CPU->fpu_owner)	90	if(THREAD==CPU->fpu_owner)
91	fpu_enable();	91	fpu_enable();
92	else	92	else
93	fpu_disable();	93	fpu_disable();
94	#else	94	#else
95	fpu_enable();	95	fpu_enable();
96	if (THREAD->fpu_context_exists)	96	if (THREAD->fpu_context_exists)
97	fpu_context_restore(THREAD->saved_fpu_context);	97	fpu_context_restore(THREAD->saved_fpu_context);
98	else {	98	else {
99	fpu_init();	99	fpu_init();
100	THREAD->fpu_context_exists=1;	100	THREAD->fpu_context_exists=1;
101	}	101	}
102	#endif	102	#endif
103	}	103	}
104		104
105	/** Take actions after THREAD had run.	105	/** Take actions after THREAD had run.
106	*	106	*
107	* Perform actions that need to be	107	* Perform actions that need to be
108	* taken after the running thread	108	* taken after the running thread
109	* had been preempted by the scheduler.	109	* had been preempted by the scheduler.
110	*	110	*
111	* THREAD->lock is locked on entry	111	* THREAD->lock is locked on entry
112	*	112	*
113	*/	113	*/
114	void after_thread_ran(void)	114	void after_thread_ran(void)
115	{	115	{
116	after_thread_ran_arch();	116	after_thread_ran_arch();
117	}	117	}
118		118
119	#ifdef CONFIG_FPU_LAZY	119	#ifdef CONFIG_FPU_LAZY
120	void scheduler_fpu_lazy_request(void)	120	void scheduler_fpu_lazy_request(void)
121	{	121	{
122	restart:	122	restart:
123	fpu_enable();	123	fpu_enable();
124	spinlock_lock(&CPU->lock);	124	spinlock_lock(&CPU->lock);
125		125
126	/* Save old context */	126	/* Save old context */
127	if (CPU->fpu_owner != NULL) {	127	if (CPU->fpu_owner != NULL) {
128	spinlock_lock(&CPU->fpu_owner->lock);	128	spinlock_lock(&CPU->fpu_owner->lock);
129	fpu_context_save(CPU->fpu_owner->saved_fpu_context);	129	fpu_context_save(CPU->fpu_owner->saved_fpu_context);
130	/* don't prevent migration */	130	/* don't prevent migration */
131	CPU->fpu_owner->fpu_context_engaged=0;	131	CPU->fpu_owner->fpu_context_engaged=0;
132	spinlock_unlock(&CPU->fpu_owner->lock);	132	spinlock_unlock(&CPU->fpu_owner->lock);
133	CPU->fpu_owner = NULL;	133	CPU->fpu_owner = NULL;
134	}	134	}
135		135
136	spinlock_lock(&THREAD->lock);	136	spinlock_lock(&THREAD->lock);
137	if (THREAD->fpu_context_exists) {	137	if (THREAD->fpu_context_exists) {
138	fpu_context_restore(THREAD->saved_fpu_context);	138	fpu_context_restore(THREAD->saved_fpu_context);
139	} else {	139	} else {
140	/* Allocate FPU context */	140	/* Allocate FPU context */
141	if (!THREAD->saved_fpu_context) {	141	if (!THREAD->saved_fpu_context) {
142	/* Might sleep */	142	/* Might sleep */
143	spinlock_unlock(&THREAD->lock);	143	spinlock_unlock(&THREAD->lock);
144	spinlock_unlock(&CPU->lock);	144	spinlock_unlock(&CPU->lock);
145	THREAD->saved_fpu_context = slab_alloc(fpu_context_slab,	145	THREAD->saved_fpu_context = slab_alloc(fpu_context_slab,
146	0);	146	0);
147	/* We may have switched CPUs during slab_alloc */	147	/* We may have switched CPUs during slab_alloc */
148	goto restart;	148	goto restart;
149	}	149	}
150	fpu_init();	150	fpu_init();
151	THREAD->fpu_context_exists=1;	151	THREAD->fpu_context_exists=1;
152	}	152	}
153	CPU->fpu_owner=THREAD;	153	CPU->fpu_owner=THREAD;
154	THREAD->fpu_context_engaged = 1;	154	THREAD->fpu_context_engaged = 1;
155	spinlock_unlock(&THREAD->lock);	155	spinlock_unlock(&THREAD->lock);
156		156
157	spinlock_unlock(&CPU->lock);	157	spinlock_unlock(&CPU->lock);
158	}	158	}
159	#endif	159	#endif
160		160
161	/** Initialize scheduler	161	/** Initialize scheduler
162	*	162	*
163	* Initialize kernel scheduler.	163	* Initialize kernel scheduler.
164	*	164	*
165	*/	165	*/
166	void scheduler_init(void)	166	void scheduler_init(void)
167	{	167	{
168	}	168	}
169		169
170	/** Get thread to be scheduled	170	/** Get thread to be scheduled
171	*	171	*
172	* Get the optimal thread to be scheduled	172	* Get the optimal thread to be scheduled
173	* according to thread accounting and scheduler	173	* according to thread accounting and scheduler
174	* policy.	174	* policy.
175	*	175	*
176	* @return Thread to be scheduled.	176	* @return Thread to be scheduled.
177	*	177	*
178	*/	178	*/
179	static thread_t *find_best_thread(void)	179	static thread_t *find_best_thread(void)
180	{	180	{
181	thread_t *t;	181	thread_t *t;
182	runq_t *r;	182	runq_t *r;
183	int i;	183	int i;
184		184
185	ASSERT(CPU != NULL);	185	ASSERT(CPU != NULL);
186		186
187	loop:	187	loop:
188	interrupts_enable();	188	interrupts_enable();
189		189
190	if (atomic_get(&CPU->nrdy) == 0) {	190	if (atomic_get(&CPU->nrdy) == 0) {
191	/*	191	/*
192	* For there was nothing to run, the CPU goes to sleep	192	* For there was nothing to run, the CPU goes to sleep
193	* until a hardware interrupt or an IPI comes.	193	* until a hardware interrupt or an IPI comes.
194	* This improves energy saving and hyperthreading.	194	* This improves energy saving and hyperthreading.
195	*/	195	*/
196		196
197	/*	197	/*
198	* An interrupt might occur right now and wake up a thread.	198	* An interrupt might occur right now and wake up a thread.
199	* In such case, the CPU will continue to go to sleep	199	* In such case, the CPU will continue to go to sleep
200	* even though there is a runnable thread.	200	* even though there is a runnable thread.
201	*/	201	*/
202		202
203	cpu_sleep();	203	cpu_sleep();
204	goto loop;	204	goto loop;
205	}	205	}
206		206
207	interrupts_disable();	207	interrupts_disable();
208		208
209	for (i = 0; i<RQ_COUNT; i++) {	209	for (i = 0; i<RQ_COUNT; i++) {
210	r = &CPU->rq[i];	210	r = &CPU->rq[i];
211	spinlock_lock(&r->lock);	211	spinlock_lock(&r->lock);
212	if (r->n == 0) {	212	if (r->n == 0) {
213	/*	213	/*
214	* If this queue is empty, try a lower-priority queue.	214	* If this queue is empty, try a lower-priority queue.
215	*/	215	*/
216	spinlock_unlock(&r->lock);	216	spinlock_unlock(&r->lock);
217	continue;	217	continue;
218	}	218	}
219		219
220	atomic_dec(&CPU->nrdy);	220	atomic_dec(&CPU->nrdy);
221	atomic_dec(&nrdy);	221	atomic_dec(&nrdy);
222	r->n--;	222	r->n--;
223		223
224	/*	224	/*
225	* Take the first thread from the queue.	225	* Take the first thread from the queue.
226	*/	226	*/
227	t = list_get_instance(r->rq_head.next, thread_t, rq_link);	227	t = list_get_instance(r->rq_head.next, thread_t, rq_link);
228	list_remove(&t->rq_link);	228	list_remove(&t->rq_link);
229		229
230	spinlock_unlock(&r->lock);	230	spinlock_unlock(&r->lock);
231		231
232	spinlock_lock(&t->lock);	232	spinlock_lock(&t->lock);
233	t->cpu = CPU;	233	t->cpu = CPU;
234		234
235	t->ticks = us2ticks((i+1)*10000);	235	t->ticks = us2ticks((i+1)*10000);
236	t->priority = i; /* correct rq index */	236	t->priority = i; /* correct rq index */
237		237
238	/*	238	/*
239	* Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge.	239	* Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge.
240	*/	240	*/
241	t->flags &= ~X_STOLEN;	241	t->flags &= ~X_STOLEN;
242	spinlock_unlock(&t->lock);	242	spinlock_unlock(&t->lock);
243		243
244	return t;	244	return t;
245	}	245	}
246	goto loop;	246	goto loop;
247		247
248	}	248	}
249		249
250	/** Prevent rq starvation	250	/** Prevent rq starvation
251	*	251	*
252	* Prevent low priority threads from starving in rq's.	252	* Prevent low priority threads from starving in rq's.
253	*	253	*
254	* When the function decides to relink rq's, it reconnects	254	* When the function decides to relink rq's, it reconnects
255	* respective pointers so that in result threads with 'pri'	255	* respective pointers so that in result threads with 'pri'
256	* greater or equal @start are moved to a higher-priority queue.	256	* greater or equal start are moved to a higher-priority queue.
257	*	257	*
258	* @param start Threshold priority.	258	* @param start Threshold priority.
259	*	259	*
260	*/	260	*/
261	static void relink_rq(int start)	261	static void relink_rq(int start)
262	{	262	{
263	link_t head;	263	link_t head;
264	runq_t *r;	264	runq_t *r;
265	int i, n;	265	int i, n;
266		266
267	list_initialize(&head);	267	list_initialize(&head);
268	spinlock_lock(&CPU->lock);	268	spinlock_lock(&CPU->lock);
269	if (CPU->needs_relink > NEEDS_RELINK_MAX) {	269	if (CPU->needs_relink > NEEDS_RELINK_MAX) {
270	for (i = start; i<RQ_COUNT-1; i++) {	270	for (i = start; i<RQ_COUNT-1; i++) {
271	/* remember and empty rq[i + 1] */	271	/* remember and empty rq[i + 1] */
272	r = &CPU->rq[i + 1];	272	r = &CPU->rq[i + 1];
273	spinlock_lock(&r->lock);	273	spinlock_lock(&r->lock);
274	list_concat(&head, &r->rq_head);	274	list_concat(&head, &r->rq_head);
275	n = r->n;	275	n = r->n;
276	r->n = 0;	276	r->n = 0;
277	spinlock_unlock(&r->lock);	277	spinlock_unlock(&r->lock);
278		278
279	/* append rq[i + 1] to rq[i] */	279	/* append rq[i + 1] to rq[i] */
280	r = &CPU->rq[i];	280	r = &CPU->rq[i];
281	spinlock_lock(&r->lock);	281	spinlock_lock(&r->lock);
282	list_concat(&r->rq_head, &head);	282	list_concat(&r->rq_head, &head);
283	r->n += n;	283	r->n += n;
284	spinlock_unlock(&r->lock);	284	spinlock_unlock(&r->lock);
285	}	285	}
286	CPU->needs_relink = 0;	286	CPU->needs_relink = 0;
287	}	287	}
288	spinlock_unlock(&CPU->lock);	288	spinlock_unlock(&CPU->lock);
289		289
290	}	290	}
291		291
292	/** The scheduler	292	/** The scheduler
293	*	293	*
294	* The thread scheduling procedure.	294	* The thread scheduling procedure.
295	* Passes control directly to	295	* Passes control directly to
296	* scheduler_separated_stack().	296	* scheduler_separated_stack().
297	*	297	*
298	*/	298	*/
299	void scheduler(void)	299	void scheduler(void)
300	{	300	{
301	volatile ipl_t ipl;	301	volatile ipl_t ipl;
302		302
303	ASSERT(CPU != NULL);	303	ASSERT(CPU != NULL);
304		304
305	ipl = interrupts_disable();	305	ipl = interrupts_disable();
306		306
307	if (atomic_get(&haltstate))	307	if (atomic_get(&haltstate))
308	halt();	308	halt();
309		309
310	if (THREAD) {	310	if (THREAD) {
311	spinlock_lock(&THREAD->lock);	311	spinlock_lock(&THREAD->lock);
312	#ifndef CONFIG_FPU_LAZY	312	#ifndef CONFIG_FPU_LAZY
313	fpu_context_save(THREAD->saved_fpu_context);	313	fpu_context_save(THREAD->saved_fpu_context);
314	#endif	314	#endif
315	if (!context_save(&THREAD->saved_context)) {	315	if (!context_save(&THREAD->saved_context)) {
316	/*	316	/*
317	* This is the place where threads leave scheduler();	317	* This is the place where threads leave scheduler();
318	*/	318	*/
319	spinlock_unlock(&THREAD->lock);	319	spinlock_unlock(&THREAD->lock);
320	interrupts_restore(THREAD->saved_context.ipl);	320	interrupts_restore(THREAD->saved_context.ipl);
321		321
322	return;	322	return;
323	}	323	}
324		324
325	/*	325	/*
326	* Interrupt priority level of preempted thread is recorded here	326	* Interrupt priority level of preempted thread is recorded here
327	* to facilitate scheduler() invocations from interrupts_disable()'d	327	* to facilitate scheduler() invocations from interrupts_disable()'d
328	* code (e.g. waitq_sleep_timeout()).	328	* code (e.g. waitq_sleep_timeout()).
329	*/	329	*/
330	THREAD->saved_context.ipl = ipl;	330	THREAD->saved_context.ipl = ipl;
331	}	331	}
332		332
333	/*	333	/*
334	* Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM	334	* Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM
335	* and preemption counter. At this point THE could be coming either	335	* and preemption counter. At this point THE could be coming either
336	* from THREAD's or CPU's stack.	336	* from THREAD's or CPU's stack.
337	*/	337	*/
338	the_copy(THE, (the_t *) CPU->stack);	338	the_copy(THE, (the_t *) CPU->stack);
339		339
340	/*	340	/*
341	* We may not keep the old stack.	341	* We may not keep the old stack.
342	* Reason: If we kept the old stack and got blocked, for instance, in	342	* Reason: If we kept the old stack and got blocked, for instance, in
343	* find_best_thread(), the old thread could get rescheduled by another	343	* find_best_thread(), the old thread could get rescheduled by another
344	* CPU and overwrite the part of its own stack that was also used by	344	* CPU and overwrite the part of its own stack that was also used by
345	* the scheduler on this CPU.	345	* the scheduler on this CPU.
346	*	346	*
347	* Moreover, we have to bypass the compiler-generated POP sequence	347	* Moreover, we have to bypass the compiler-generated POP sequence
348	* which is fooled by SP being set to the very top of the stack.	348	* which is fooled by SP being set to the very top of the stack.
349	* Therefore the scheduler() function continues in	349	* Therefore the scheduler() function continues in
350	* scheduler_separated_stack().	350	* scheduler_separated_stack().
351	*/	351	*/
352	context_save(&CPU->saved_context);	352	context_save(&CPU->saved_context);
353	context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (__address) CPU->stack, CPU_STACK_SIZE);	353	context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (__address) CPU->stack, CPU_STACK_SIZE);
354	context_restore(&CPU->saved_context);	354	context_restore(&CPU->saved_context);
355	/* not reached */	355	/* not reached */
356	}	356	}
357		357
358	/** Scheduler stack switch wrapper	358	/** Scheduler stack switch wrapper
359	*	359	*
360	* Second part of the scheduler() function	360	* Second part of the scheduler() function
361	* using new stack. Handling the actual context	361	* using new stack. Handling the actual context
362	* switch to a new thread.	362	* switch to a new thread.
363	*	363	*
364	* Assume THREAD->lock is held.	364	* Assume THREAD->lock is held.
365	*/	365	*/
366	void scheduler_separated_stack(void)	366	void scheduler_separated_stack(void)
367	{	367	{
368	int priority;	368	int priority;
369		369
370	ASSERT(CPU != NULL);	370	ASSERT(CPU != NULL);
371		371
372	if (THREAD) {	372	if (THREAD) {
373	/* must be run after the switch to scheduler stack */	373	/* must be run after the switch to scheduler stack */
374	after_thread_ran();	374	after_thread_ran();
375		375
376	switch (THREAD->state) {	376	switch (THREAD->state) {
377	case Running:	377	case Running:
378	spinlock_unlock(&THREAD->lock);	378	spinlock_unlock(&THREAD->lock);
379	thread_ready(THREAD);	379	thread_ready(THREAD);
380	break;	380	break;
381		381
382	case Exiting:	382	case Exiting:
383	repeat:	383	repeat:
384	if (THREAD->detached) {	384	if (THREAD->detached) {
385	thread_destroy(THREAD);	385	thread_destroy(THREAD);
386	} else {	386	} else {
387	/*	387	/*
388	* The thread structure is kept allocated until somebody	388	* The thread structure is kept allocated until somebody
389	* calls thread_detach() on it.	389	* calls thread_detach() on it.
390	*/	390	*/
391	if (!spinlock_trylock(&THREAD->join_wq.lock)) {	391	if (!spinlock_trylock(&THREAD->join_wq.lock)) {
392	/*	392	/*
393	* Avoid deadlock.	393	* Avoid deadlock.
394	*/	394	*/
395	spinlock_unlock(&THREAD->lock);	395	spinlock_unlock(&THREAD->lock);
396	delay(10);	396	delay(10);
397	spinlock_lock(&THREAD->lock);	397	spinlock_lock(&THREAD->lock);
398	goto repeat;	398	goto repeat;
399	}	399	}
400	_waitq_wakeup_unsafe(&THREAD->join_wq, false);	400	_waitq_wakeup_unsafe(&THREAD->join_wq, false);
401	spinlock_unlock(&THREAD->join_wq.lock);	401	spinlock_unlock(&THREAD->join_wq.lock);
402		402
403	THREAD->state = Undead;	403	THREAD->state = Undead;
404	spinlock_unlock(&THREAD->lock);	404	spinlock_unlock(&THREAD->lock);
405	}	405	}
406	break;	406	break;
407		407
408	case Sleeping:	408	case Sleeping:
409	/*	409	/*
410	* Prefer the thread after it's woken up.	410	* Prefer the thread after it's woken up.
411	*/	411	*/
412	THREAD->priority = -1;	412	THREAD->priority = -1;
413		413
414	/*	414	/*
415	* We need to release wq->lock which we locked in waitq_sleep().	415	* We need to release wq->lock which we locked in waitq_sleep().
416	* Address of wq->lock is kept in THREAD->sleep_queue.	416	* Address of wq->lock is kept in THREAD->sleep_queue.
417	*/	417	*/
418	spinlock_unlock(&THREAD->sleep_queue->lock);	418	spinlock_unlock(&THREAD->sleep_queue->lock);
419		419
420	/*	420	/*
421	* Check for possible requests for out-of-context invocation.	421	* Check for possible requests for out-of-context invocation.
422	*/	422	*/
423	if (THREAD->call_me) {	423	if (THREAD->call_me) {
424	THREAD->call_me(THREAD->call_me_with);	424	THREAD->call_me(THREAD->call_me_with);
425	THREAD->call_me = NULL;	425	THREAD->call_me = NULL;
426	THREAD->call_me_with = NULL;	426	THREAD->call_me_with = NULL;
427	}	427	}
428		428
429	spinlock_unlock(&THREAD->lock);	429	spinlock_unlock(&THREAD->lock);
430		430
431	break;	431	break;
432		432
433	default:	433	default:
434	/*	434	/*
435	* Entering state is unexpected.	435	* Entering state is unexpected.
436	*/	436	*/
437	panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]);	437	panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]);
438	break;	438	break;
439	}	439	}
440		440
441	THREAD = NULL;	441	THREAD = NULL;
442	}	442	}
443		443
444	THREAD = find_best_thread();	444	THREAD = find_best_thread();
445		445
446	spinlock_lock(&THREAD->lock);	446	spinlock_lock(&THREAD->lock);
447	priority = THREAD->priority;	447	priority = THREAD->priority;
448	spinlock_unlock(&THREAD->lock);	448	spinlock_unlock(&THREAD->lock);
449		449
450	relink_rq(priority);	450	relink_rq(priority);
451		451
452	/*	452	/*
453	* If both the old and the new task are the same, lots of work is avoided.	453	* If both the old and the new task are the same, lots of work is avoided.
454	*/	454	*/
455	if (TASK != THREAD->task) {	455	if (TASK != THREAD->task) {
456	as_t *as1 = NULL;	456	as_t *as1 = NULL;
457	as_t *as2;	457	as_t *as2;
458		458
459	if (TASK) {	459	if (TASK) {
460	spinlock_lock(&TASK->lock);	460	spinlock_lock(&TASK->lock);
461	as1 = TASK->as;	461	as1 = TASK->as;
462	spinlock_unlock(&TASK->lock);	462	spinlock_unlock(&TASK->lock);
463	}	463	}
464		464
465	spinlock_lock(&THREAD->task->lock);	465	spinlock_lock(&THREAD->task->lock);
466	as2 = THREAD->task->as;	466	as2 = THREAD->task->as;
467	spinlock_unlock(&THREAD->task->lock);	467	spinlock_unlock(&THREAD->task->lock);
468		468
469	/*	469	/*
470	* Note that it is possible for two tasks to share one address space.	470	* Note that it is possible for two tasks to share one address space.
471	*/	471	*/
472	if (as1 != as2) {	472	if (as1 != as2) {
473	/*	473	/*
474	* Both tasks and address spaces are different.	474	* Both tasks and address spaces are different.
475	* Replace the old one with the new one.	475	* Replace the old one with the new one.
476	*/	476	*/
477	as_switch(as1, as2);	477	as_switch(as1, as2);
478	}	478	}
479	TASK = THREAD->task;	479	TASK = THREAD->task;
480	before_task_runs();	480	before_task_runs();
481	}	481	}
482		482
483	spinlock_lock(&THREAD->lock);	483	spinlock_lock(&THREAD->lock);
484	THREAD->state = Running;	484	THREAD->state = Running;
485		485
486	#ifdef SCHEDULER_VERBOSE	486	#ifdef SCHEDULER_VERBOSE
487	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	printf("cpu%d: tid %d (priority=%d,ticks=%lld,nrdy=%ld)\n", CPU->id, THREAD->tid, THREAD->priority, THREAD->ticks, atomic_get(&CPU->nrdy));
488	#endif	488	#endif
489		489
490	/*	490	/*
491	* Some architectures provide late kernel PA2KA(identity)	491	* Some architectures provide late kernel PA2KA(identity)
492	* mapping in a page fault handler. However, the page fault	492	* mapping in a page fault handler. However, the page fault
493	* handler uses the kernel stack of the running thread and	493	* handler uses the kernel stack of the running thread and
494	* therefore cannot be used to map it. The kernel stack, if	494	* therefore cannot be used to map it. The kernel stack, if
495	* necessary, is to be mapped in before_thread_runs(). This	495	* necessary, is to be mapped in before_thread_runs(). This
496	* function must be executed before the switch to the new stack.	496	* function must be executed before the switch to the new stack.
497	*/	497	*/
498	before_thread_runs();	498	before_thread_runs();
499		499
500	/*	500	/*

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/proc/scheduler.c @ 1705 – Rev 1705 → 1708