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.
 */
 
/**
 * @file    scheduler.c
 * @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 1571	Rev 1576
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	* @file scheduler.c	30	* @file scheduler.c
31	* @brief Scheduler and load balancing.	31	* @brief Scheduler and load balancing.
32	*	32	*
33	* This file contains the scheduler and kcpulb kernel thread which	33	* This file contains the scheduler and kcpulb kernel thread which
34	* performs load-balancing of per-CPU run queues.	34	* performs load-balancing of per-CPU run queues.
35	*/	35	*/
36		36
37	#include <proc/scheduler.h>	37	#include <proc/scheduler.h>
38	#include <proc/thread.h>	38	#include <proc/thread.h>
39	#include <proc/task.h>	39	#include <proc/task.h>
40	#include <mm/frame.h>	40	#include <mm/frame.h>
41	#include <mm/page.h>	41	#include <mm/page.h>
42	#include <mm/as.h>	42	#include <mm/as.h>
43	#include <time/delay.h>	43	#include <time/delay.h>
44	#include <arch/asm.h>	44	#include <arch/asm.h>
45	#include <arch/faddr.h>	45	#include <arch/faddr.h>
46	#include <atomic.h>	46	#include <atomic.h>
47	#include <synch/spinlock.h>	47	#include <synch/spinlock.h>
48	#include <config.h>	48	#include <config.h>
49	#include <context.h>	49	#include <context.h>
50	#include <func.h>	50	#include <func.h>
51	#include <arch.h>	51	#include <arch.h>
52	#include <adt/list.h>	52	#include <adt/list.h>
53	#include <panic.h>	53	#include <panic.h>
54	#include <typedefs.h>	54	#include <typedefs.h>
55	#include <cpu.h>	55	#include <cpu.h>
56	#include <print.h>	56	#include <print.h>
57	#include <debug.h>	57	#include <debug.h>
58		58
59	static void before_task_runs(void);	59	static void before_task_runs(void);
60	static void before_thread_runs(void);	60	static void before_thread_runs(void);
61	static void after_thread_ran(void);	61	static void after_thread_ran(void);
62	static void scheduler_separated_stack(void);	62	static void scheduler_separated_stack(void);
63		63
64	atomic_t nrdy; /*< Number of ready threads in the system. /	64	atomic_t nrdy; /*< Number of ready threads in the system. /
65		65
66	/** Carry out actions before new task runs. */	66	/** Carry out actions before new task runs. */
67	void before_task_runs(void)	67	void before_task_runs(void)
68	{	68	{
69	before_task_runs_arch();	69	before_task_runs_arch();
70	}	70	}
71		71
72	/** Take actions before new thread runs.	72	/** Take actions before new thread runs.
73	*	73	*
74	* Perform actions that need to be	74	* Perform actions that need to be
75	* taken before the newly selected	75	* taken before the newly selected
76	* tread is passed control.	76	* tread is passed control.
77	*	77	*
78	* THREAD->lock is locked on entry	78	* THREAD->lock is locked on entry
79	*	79	*
80	*/	80	*/
81	void before_thread_runs(void)	81	void before_thread_runs(void)
82	{	82	{
83	before_thread_runs_arch();	83	before_thread_runs_arch();
84	#ifdef CONFIG_FPU_LAZY	84	#ifdef CONFIG_FPU_LAZY
85	if(THREAD==CPU->fpu_owner)	85	if(THREAD==CPU->fpu_owner)
86	fpu_enable();	86	fpu_enable();
87	else	87	else
88	fpu_disable();	88	fpu_disable();
89	#else	89	#else
90	fpu_enable();	90	fpu_enable();
91	if (THREAD->fpu_context_exists)	91	if (THREAD->fpu_context_exists)
92	fpu_context_restore(THREAD->saved_fpu_context);	92	fpu_context_restore(THREAD->saved_fpu_context);
93	else {	93	else {
94	fpu_init();	94	fpu_init();
95	THREAD->fpu_context_exists=1;	95	THREAD->fpu_context_exists=1;
96	}	96	}
97	#endif	97	#endif
98	}	98	}
99		99
100	/** Take actions after THREAD had run.	100	/** Take actions after THREAD had run.
101	*	101	*
102	* Perform actions that need to be	102	* Perform actions that need to be
103	* taken after the running thread	103	* taken after the running thread
104	* had been preempted by the scheduler.	104	* had been preempted by the scheduler.
105	*	105	*
106	* THREAD->lock is locked on entry	106	* THREAD->lock is locked on entry
107	*	107	*
108	*/	108	*/
109	void after_thread_ran(void)	109	void after_thread_ran(void)
110	{	110	{
111	after_thread_ran_arch();	111	after_thread_ran_arch();
112	}	112	}
113		113
114	#ifdef CONFIG_FPU_LAZY	114	#ifdef CONFIG_FPU_LAZY
115	void scheduler_fpu_lazy_request(void)	115	void scheduler_fpu_lazy_request(void)
116	{	116	{
117	restart:	117	restart:
118	fpu_enable();	118	fpu_enable();
119	spinlock_lock(&CPU->lock);	119	spinlock_lock(&CPU->lock);
120		120
121	/* Save old context */	121	/* Save old context */
122	if (CPU->fpu_owner != NULL) {	122	if (CPU->fpu_owner != NULL) {
123	spinlock_lock(&CPU->fpu_owner->lock);	123	spinlock_lock(&CPU->fpu_owner->lock);
124	fpu_context_save(CPU->fpu_owner->saved_fpu_context);	124	fpu_context_save(CPU->fpu_owner->saved_fpu_context);
125	/* don't prevent migration */	125	/* don't prevent migration */
126	CPU->fpu_owner->fpu_context_engaged=0;	126	CPU->fpu_owner->fpu_context_engaged=0;
127	spinlock_unlock(&CPU->fpu_owner->lock);	127	spinlock_unlock(&CPU->fpu_owner->lock);
128	CPU->fpu_owner = NULL;	128	CPU->fpu_owner = NULL;
129	}	129	}
130		130
131	spinlock_lock(&THREAD->lock);	131	spinlock_lock(&THREAD->lock);
132	if (THREAD->fpu_context_exists) {	132	if (THREAD->fpu_context_exists) {
133	fpu_context_restore(THREAD->saved_fpu_context);	133	fpu_context_restore(THREAD->saved_fpu_context);
134	} else {	134	} else {
135	/* Allocate FPU context */	135	/* Allocate FPU context */
136	if (!THREAD->saved_fpu_context) {	136	if (!THREAD->saved_fpu_context) {
137	/* Might sleep */	137	/* Might sleep */
138	spinlock_unlock(&THREAD->lock);	138	spinlock_unlock(&THREAD->lock);
139	spinlock_unlock(&CPU->lock);	139	spinlock_unlock(&CPU->lock);
140	THREAD->saved_fpu_context = slab_alloc(fpu_context_slab,	140	THREAD->saved_fpu_context = slab_alloc(fpu_context_slab,
141	0);	141	0);
142	/* We may have switched CPUs during slab_alloc */	142	/* We may have switched CPUs during slab_alloc */
143	goto restart;	143	goto restart;
144	}	144	}
145	fpu_init();	145	fpu_init();
146	THREAD->fpu_context_exists=1;	146	THREAD->fpu_context_exists=1;
147	}	147	}
148	CPU->fpu_owner=THREAD;	148	CPU->fpu_owner=THREAD;
149	THREAD->fpu_context_engaged = 1;	149	THREAD->fpu_context_engaged = 1;
150	spinlock_unlock(&THREAD->lock);	150	spinlock_unlock(&THREAD->lock);
151		151
152	spinlock_unlock(&CPU->lock);	152	spinlock_unlock(&CPU->lock);
153	}	153	}
154	#endif	154	#endif
155		155
156	/** Initialize scheduler	156	/** Initialize scheduler
157	*	157	*
158	* Initialize kernel scheduler.	158	* Initialize kernel scheduler.
159	*	159	*
160	*/	160	*/
161	void scheduler_init(void)	161	void scheduler_init(void)
162	{	162	{
163	}	163	}
164		164
165	/** Get thread to be scheduled	165	/** Get thread to be scheduled
166	*	166	*
167	* Get the optimal thread to be scheduled	167	* Get the optimal thread to be scheduled
168	* according to thread accounting and scheduler	168	* according to thread accounting and scheduler
169	* policy.	169	* policy.
170	*	170	*
171	* @return Thread to be scheduled.	171	* @return Thread to be scheduled.
172	*	172	*
173	*/	173	*/
174	static thread_t *find_best_thread(void)	174	static thread_t *find_best_thread(void)
175	{	175	{
176	thread_t *t;	176	thread_t *t;
177	runq_t *r;	177	runq_t *r;
178	int i;	178	int i;
179		179
180	ASSERT(CPU != NULL);	180	ASSERT(CPU != NULL);
181		181
182	loop:	182	loop:
183	interrupts_enable();	183	interrupts_enable();
184		184
185	if (atomic_get(&CPU->nrdy) == 0) {	185	if (atomic_get(&CPU->nrdy) == 0) {
186	/*	186	/*
187	* For there was nothing to run, the CPU goes to sleep	187	* For there was nothing to run, the CPU goes to sleep
188	* until a hardware interrupt or an IPI comes.	188	* until a hardware interrupt or an IPI comes.
189	* This improves energy saving and hyperthreading.	189	* This improves energy saving and hyperthreading.
190	*/	190	*/
191		191
192	/*	192	/*
193	* An interrupt might occur right now and wake up a thread.	193	* An interrupt might occur right now and wake up a thread.
194	* In such case, the CPU will continue to go to sleep	194	* In such case, the CPU will continue to go to sleep
195	* even though there is a runnable thread.	195	* even though there is a runnable thread.
196	*/	196	*/
197		197
198	cpu_sleep();	198	cpu_sleep();
199	goto loop;	199	goto loop;
200	}	200	}
201		201
202	interrupts_disable();	202	interrupts_disable();
203		203
204	for (i = 0; i<RQ_COUNT; i++) {	204	for (i = 0; i<RQ_COUNT; i++) {
205	r = &CPU->rq[i];	205	r = &CPU->rq[i];
206	spinlock_lock(&r->lock);	206	spinlock_lock(&r->lock);
207	if (r->n == 0) {	207	if (r->n == 0) {
208	/*	208	/*
209	* If this queue is empty, try a lower-priority queue.	209	* If this queue is empty, try a lower-priority queue.
210	*/	210	*/
211	spinlock_unlock(&r->lock);	211	spinlock_unlock(&r->lock);
212	continue;	212	continue;
213	}	213	}
214		214
215	atomic_dec(&CPU->nrdy);	215	atomic_dec(&CPU->nrdy);
216	atomic_dec(&nrdy);	216	atomic_dec(&nrdy);
217	r->n--;	217	r->n--;
218		218
219	/*	219	/*
220	* Take the first thread from the queue.	220	* Take the first thread from the queue.
221	*/	221	*/
222	t = list_get_instance(r->rq_head.next, thread_t, rq_link);	222	t = list_get_instance(r->rq_head.next, thread_t, rq_link);
223	list_remove(&t->rq_link);	223	list_remove(&t->rq_link);
224		224
225	spinlock_unlock(&r->lock);	225	spinlock_unlock(&r->lock);
226		226
227	spinlock_lock(&t->lock);	227	spinlock_lock(&t->lock);
228	t->cpu = CPU;	228	t->cpu = CPU;
229		229
230	t->ticks = us2ticks((i+1)*10000);	230	t->ticks = us2ticks((i+1)*10000);
231	t->priority = i; /* correct rq index */	231	t->priority = i; /* correct rq index */
232		232
233	/*	233	/*
234	* Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge.	234	* Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge.
235	*/	235	*/
236	t->flags &= ~X_STOLEN;	236	t->flags &= ~X_STOLEN;
237	spinlock_unlock(&t->lock);	237	spinlock_unlock(&t->lock);
238		238
239	return t;	239	return t;
240	}	240	}
241	goto loop;	241	goto loop;
242		242
243	}	243	}
244		244
245	/** Prevent rq starvation	245	/** Prevent rq starvation
246	*	246	*
247	* Prevent low priority threads from starving in rq's.	247	* Prevent low priority threads from starving in rq's.
248	*	248	*
249	* When the function decides to relink rq's, it reconnects	249	* When the function decides to relink rq's, it reconnects
250	* respective pointers so that in result threads with 'pri'	250	* respective pointers so that in result threads with 'pri'
251	* greater or equal @start are moved to a higher-priority queue.	251	* greater or equal @start are moved to a higher-priority queue.
252	*	252	*
253	* @param start Threshold priority.	253	* @param start Threshold priority.
254	*	254	*
255	*/	255	*/
256	static void relink_rq(int start)	256	static void relink_rq(int start)
257	{	257	{
258	link_t head;	258	link_t head;
259	runq_t *r;	259	runq_t *r;
260	int i, n;	260	int i, n;
261		261
262	list_initialize(&head);	262	list_initialize(&head);
263	spinlock_lock(&CPU->lock);	263	spinlock_lock(&CPU->lock);
264	if (CPU->needs_relink > NEEDS_RELINK_MAX) {	264	if (CPU->needs_relink > NEEDS_RELINK_MAX) {
265	for (i = start; i<RQ_COUNT-1; i++) {	265	for (i = start; i<RQ_COUNT-1; i++) {
266	/* remember and empty rq[i + 1] */	266	/* remember and empty rq[i + 1] */
267	r = &CPU->rq[i + 1];	267	r = &CPU->rq[i + 1];
268	spinlock_lock(&r->lock);	268	spinlock_lock(&r->lock);
269	list_concat(&head, &r->rq_head);	269	list_concat(&head, &r->rq_head);
270	n = r->n;	270	n = r->n;
271	r->n = 0;	271	r->n = 0;
272	spinlock_unlock(&r->lock);	272	spinlock_unlock(&r->lock);
273		273
274	/* append rq[i + 1] to rq[i] */	274	/* append rq[i + 1] to rq[i] */
275	r = &CPU->rq[i];	275	r = &CPU->rq[i];
276	spinlock_lock(&r->lock);	276	spinlock_lock(&r->lock);
277	list_concat(&r->rq_head, &head);	277	list_concat(&r->rq_head, &head);
278	r->n += n;	278	r->n += n;
279	spinlock_unlock(&r->lock);	279	spinlock_unlock(&r->lock);
280	}	280	}
281	CPU->needs_relink = 0;	281	CPU->needs_relink = 0;
282	}	282	}
283	spinlock_unlock(&CPU->lock);	283	spinlock_unlock(&CPU->lock);
284		284
285	}	285	}
286		286
287	/** The scheduler	287	/** The scheduler
288	*	288	*
289	* The thread scheduling procedure.	289	* The thread scheduling procedure.
290	* Passes control directly to	290	* Passes control directly to
291	* scheduler_separated_stack().	291	* scheduler_separated_stack().
292	*	292	*
293	*/	293	*/
294	void scheduler(void)	294	void scheduler(void)
295	{	295	{
296	volatile ipl_t ipl;	296	volatile ipl_t ipl;
297		297
298	ASSERT(CPU != NULL);	298	ASSERT(CPU != NULL);
299		299
300	ipl = interrupts_disable();	300	ipl = interrupts_disable();
301		301
302	if (atomic_get(&haltstate))	302	if (atomic_get(&haltstate))
303	halt();	303	halt();
304		304
305	if (THREAD) {	305	if (THREAD) {
306	spinlock_lock(&THREAD->lock);	306	spinlock_lock(&THREAD->lock);
307	#ifndef CONFIG_FPU_LAZY	307	#ifndef CONFIG_FPU_LAZY
308	fpu_context_save(THREAD->saved_fpu_context);	308	fpu_context_save(THREAD->saved_fpu_context);
309	#endif	309	#endif
310	if (!context_save(&THREAD->saved_context)) {	310	if (!context_save(&THREAD->saved_context)) {
311	/*	311	/*
312	* This is the place where threads leave scheduler();	312	* This is the place where threads leave scheduler();
313	*/	313	*/
314	spinlock_unlock(&THREAD->lock);	314	spinlock_unlock(&THREAD->lock);
315	interrupts_restore(THREAD->saved_context.ipl);	315	interrupts_restore(THREAD->saved_context.ipl);
316		316
317	return;	317	return;
318	}	318	}
319		319
320	/*	320	/*
321	* Interrupt priority level of preempted thread is recorded here	321	* Interrupt priority level of preempted thread is recorded here
322	* to facilitate scheduler() invocations from interrupts_disable()'d	322	* to facilitate scheduler() invocations from interrupts_disable()'d
323	* code (e.g. waitq_sleep_timeout()).	323	* code (e.g. waitq_sleep_timeout()).
324	*/	324	*/
325	THREAD->saved_context.ipl = ipl;	325	THREAD->saved_context.ipl = ipl;
326	}	326	}
327		327
328	/*	328	/*
329	* Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM	329	* Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM
330	* and preemption counter. At this point THE could be coming either	330	* and preemption counter. At this point THE could be coming either
331	* from THREAD's or CPU's stack.	331	* from THREAD's or CPU's stack.
332	*/	332	*/
333	the_copy(THE, (the_t *) CPU->stack);	333	the_copy(THE, (the_t *) CPU->stack);
334		334
335	/*	335	/*
336	* We may not keep the old stack.	336	* We may not keep the old stack.
337	* Reason: If we kept the old stack and got blocked, for instance, in	337	* Reason: If we kept the old stack and got blocked, for instance, in
338	* find_best_thread(), the old thread could get rescheduled by another	338	* find_best_thread(), the old thread could get rescheduled by another
339	* CPU and overwrite the part of its own stack that was also used by	339	* CPU and overwrite the part of its own stack that was also used by
340	* the scheduler on this CPU.	340	* the scheduler on this CPU.
341	*	341	*
342	* Moreover, we have to bypass the compiler-generated POP sequence	342	* Moreover, we have to bypass the compiler-generated POP sequence
343	* which is fooled by SP being set to the very top of the stack.	343	* which is fooled by SP being set to the very top of the stack.
344	* Therefore the scheduler() function continues in	344	* Therefore the scheduler() function continues in
345	* scheduler_separated_stack().	345	* scheduler_separated_stack().
346	*/	346	*/
347	context_save(&CPU->saved_context);	347	context_save(&CPU->saved_context);
348	context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (__address) CPU->stack, CPU_STACK_SIZE);	348	context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (__address) CPU->stack, CPU_STACK_SIZE);
349	context_restore(&CPU->saved_context);	349	context_restore(&CPU->saved_context);
350	/* not reached */	350	/* not reached */
351	}	351	}
352		352
353	/** Scheduler stack switch wrapper	353	/** Scheduler stack switch wrapper
354	*	354	*
355	* Second part of the scheduler() function	355	* Second part of the scheduler() function
356	* using new stack. Handling the actual context	356	* using new stack. Handling the actual context
357	* switch to a new thread.	357	* switch to a new thread.
358	*	358	*
359	* Assume THREAD->lock is held.	359	* Assume THREAD->lock is held.
360	*/	360	*/
361	void scheduler_separated_stack(void)	361	void scheduler_separated_stack(void)
362	{	362	{
363	int priority;	363	int priority;
364		364
365	ASSERT(CPU != NULL);	365	ASSERT(CPU != NULL);
366		366
367	if (THREAD) {	367	if (THREAD) {
368	/* must be run after the switch to scheduler stack */	368	/* must be run after the switch to scheduler stack */
369	after_thread_ran();	369	after_thread_ran();
370		370
371	switch (THREAD->state) {	371	switch (THREAD->state) {
372	case Running:	372	case Running:
373	spinlock_unlock(&THREAD->lock);	373	spinlock_unlock(&THREAD->lock);
374	thread_ready(THREAD);	374	thread_ready(THREAD);
375	break;	375	break;
376		376
377	case Exiting:	377	case Exiting:
378	repeat:	378	repeat:
379	if (THREAD->detached) {	379	if (THREAD->detached) {
380	thread_destroy(THREAD);	380	thread_destroy(THREAD);
381	} else {	381	} else {
382	/*	382	/*
383	* The thread structure is kept allocated until somebody	383	* The thread structure is kept allocated until somebody
384	* calls thread_detach() on it.	384	* calls thread_detach() on it.
385	*/	385	*/
386	if (!spinlock_trylock(&THREAD->join_wq.lock)) {	386	if (!spinlock_trylock(&THREAD->join_wq.lock)) {
387	/*	387	/*
388	* Avoid deadlock.	388	* Avoid deadlock.
389	*/	389	*/
390	spinlock_unlock(&THREAD->lock);	390	spinlock_unlock(&THREAD->lock);
391	delay(10);	391	delay(10);
392	spinlock_lock(&THREAD->lock);	392	spinlock_lock(&THREAD->lock);
393	goto repeat;	393	goto repeat;
394	}	394	}
395	_waitq_wakeup_unsafe(&THREAD->join_wq, false);	395	_waitq_wakeup_unsafe(&THREAD->join_wq, false);
396	spinlock_unlock(&THREAD->join_wq.lock);	396	spinlock_unlock(&THREAD->join_wq.lock);
397		397
398	THREAD->state = Undead;	398	THREAD->state = Undead;
399	spinlock_unlock(&THREAD->lock);	399	spinlock_unlock(&THREAD->lock);
400	}	400	}
401	break;	401	break;
402		402
403	case Sleeping:	403	case Sleeping:
404	/*	404	/*
405	* Prefer the thread after it's woken up.	405	* Prefer the thread after it's woken up.
406	*/	406	*/
407	THREAD->priority = -1;	407	THREAD->priority = -1;
408		408
409	/*	409	/*
410	* We need to release wq->lock which we locked in waitq_sleep().	410	* We need to release wq->lock which we locked in waitq_sleep().
411	* Address of wq->lock is kept in THREAD->sleep_queue.	411	* Address of wq->lock is kept in THREAD->sleep_queue.
412	*/	412	*/
413	spinlock_unlock(&THREAD->sleep_queue->lock);	413	spinlock_unlock(&THREAD->sleep_queue->lock);
414		414
415	/*	415	/*
416	* Check for possible requests for out-of-context invocation.	416	* Check for possible requests for out-of-context invocation.
417	*/	417	*/
418	if (THREAD->call_me) {	418	if (THREAD->call_me) {
419	THREAD->call_me(THREAD->call_me_with);	419	THREAD->call_me(THREAD->call_me_with);
420	THREAD->call_me = NULL;	420	THREAD->call_me = NULL;
421	THREAD->call_me_with = NULL;	421	THREAD->call_me_with = NULL;
422	}	422	}
423		423
424	spinlock_unlock(&THREAD->lock);	424	spinlock_unlock(&THREAD->lock);
425		425
426	break;	426	break;
427		427
428	default:	428	default:
429	/*	429	/*
430	* Entering state is unexpected.	430	* Entering state is unexpected.
431	*/	431	*/
432	panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]);	432	panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]);
433	break;	433	break;
434	}	434	}
435		435
436	THREAD = NULL;	436	THREAD = NULL;
437	}	437	}
438		438
439	THREAD = find_best_thread();	439	THREAD = find_best_thread();
440		440
441	spinlock_lock(&THREAD->lock);	441	spinlock_lock(&THREAD->lock);
442	priority = THREAD->priority;	442	priority = THREAD->priority;
443	spinlock_unlock(&THREAD->lock);	443	spinlock_unlock(&THREAD->lock);
444		444
445	relink_rq(priority);	445	relink_rq(priority);
446		446
447	/*	447	/*
448	* If both the old and the new task are the same, lots of work is avoided.	448	* If both the old and the new task are the same, lots of work is avoided.
449	*/	449	*/
450	if (TASK != THREAD->task) {	450	if (TASK != THREAD->task) {
451	as_t *as1 = NULL;	451	as_t *as1 = NULL;
452	as_t *as2;	452	as_t *as2;
453		453
454	if (TASK) {	454	if (TASK) {
455	spinlock_lock(&TASK->lock);	455	spinlock_lock(&TASK->lock);
456	as1 = TASK->as;	456	as1 = TASK->as;
457	spinlock_unlock(&TASK->lock);	457	spinlock_unlock(&TASK->lock);
458	}	458	}
459		459
460	spinlock_lock(&THREAD->task->lock);	460	spinlock_lock(&THREAD->task->lock);
461	as2 = THREAD->task->as;	461	as2 = THREAD->task->as;
462	spinlock_unlock(&THREAD->task->lock);	462	spinlock_unlock(&THREAD->task->lock);
463		463
464	/*	464	/*
465	* Note that it is possible for two tasks to share one address space.	465	* Note that it is possible for two tasks to share one address space.
466	*/	466	*/
467	if (as1 != as2) {	467	if (as1 != as2) {
468	/*	468	/*
469	* Both tasks and address spaces are different.	469	* Both tasks and address spaces are different.
470	* Replace the old one with the new one.	470	* Replace the old one with the new one.
471	*/	471	*/
472	as_switch(as1, as2);	472	as_switch(as1, as2);
473	}	473	}
474	TASK = THREAD->task;	474	TASK = THREAD->task;
475	before_task_runs();	475	before_task_runs();
476	}	476	}
477		477
478	spinlock_lock(&THREAD->lock);	478	spinlock_lock(&THREAD->lock);
479	THREAD->state = Running;	479	THREAD->state = Running;
480		480
481	#ifdef SCHEDULER_VERBOSE	481	#ifdef SCHEDULER_VERBOSE
482	printf("cpu%d: tid %d (priority=%d,ticks=%lld,nrdy=%ld)\n", CPU->id, THREAD->tid, THREAD->priority, THREAD->ticks, atomic_get(&CPU->nrdy));	482	printf("cpu%d: tid %d (priority=%d,ticks=%lld,nrdy=%ld)\n", CPU->id, THREAD->tid, THREAD->priority, THREAD->ticks, atomic_get(&CPU->nrdy));
483	#endif	483	#endif
484		484
485	/*	485	/*
486	* Some architectures provide late kernel PA2KA(identity)	486	* Some architectures provide late kernel PA2KA(identity)
487	* mapping in a page fault handler. However, the page fault	487	* mapping in a page fault handler. However, the page fault
488	* handler uses the kernel stack of the running thread and	488	* handler uses the kernel stack of the running thread and
489	* therefore cannot be used to map it. The kernel stack, if	489	* therefore cannot be used to map it. The kernel stack, if
490	* necessary, is to be mapped in before_thread_runs(). This	490	* necessary, is to be mapped in before_thread_runs(). This
491	* function must be executed before the switch to the new stack.	491	* function must be executed before the switch to the new stack.
492	*/	492	*/
493	before_thread_runs();	493	before_thread_runs();
494		494
495	/*	495	/*
496	* Copy the knowledge of CPU, TASK, THREAD and preemption counter to thread's stack.	496	* Copy the knowledge of CPU, TASK, THREAD and preemption counter to thread's stack.
497	*/	497	*/
498	the_copy(THE, (the_t *) THREAD->kstack);	498	the_copy(THE, (the_t *) THREAD->kstack);
499		499
500	context_restore(&THREAD->saved_context);	500	context_restore(&THREAD->saved_context);

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/proc/scheduler.c – Rev 1571 → 1576