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.
 */
 
#include <proc/scheduler.h>
#include <proc/thread.h>
#include <proc/task.h>
#include <cpu.h>
#include <mm/vm.h>
#include <config.h>
#include <context.h>
#include <func.h>
#include <arch.h>
#include <arch/asm.h>
#include <list.h>
#include <panic.h>
#include <typedefs.h>
#include <mm/page.h>
#include <synch/spinlock.h>
#include <arch/faddr.h>
#include <arch/atomic.h>
#include <print.h>
#include <mm/frame.h>
#include <mm/heap.h>
 
 
volatile int nrdy;
 
 
/** Take actions before new thread runs
 *
 * Perform actions that need to be
 * taken before the newly selected
 * tread is passed control.
 *
 */
void before_thread_runs(void)
{
    before_thread_runs_arch();
    fpu_context_restore(&(THREAD->saved_fpu_context));
}
 
 
/** 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.
 *
 */
struct thread *find_best_thread(void)
{
    thread_t *t;
    runq_t *r;
    int i, n;
 
loop:
    cpu_priority_high();
 
    spinlock_lock(&CPU->lock);
    n = CPU->nrdy;
    spinlock_unlock(&CPU->lock);
 
    cpu_priority_low();
   
    if (n == 0) {
        #ifdef __SMP__
        /*
         * If the load balancing thread is not running, wake it up and
         * set CPU-private flag that the kcpulb has been started.
         */
        if (test_and_set(&CPU->kcpulbstarted) == 0) {
            waitq_wakeup(&CPU->kcpulb_wq, 0);
            goto loop;
        }
        #endif /* __SMP__ */
       
        /*
         * 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.
         * On the other hand, several hardware interrupts can be ignored.
         */
         cpu_sleep();
         goto loop;
    }
 
    cpu_priority_high();
   
    i = 0;
retry:
    for (; 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;
        }
   
        /* avoid deadlock with relink_rq() */
        if (!spinlock_trylock(&CPU->lock)) {
            /*
             * Unlock r and try again.
             */
            spinlock_unlock(&r->lock);
            goto retry;
        }
        CPU->nrdy--;
        spinlock_unlock(&CPU->lock);
 
        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->pri = i; /* eventually 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.
 *
 */
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.
 *
 */
void scheduler(void)
{
    volatile pri_t pri;
 
    pri = cpu_priority_high();
 
    if (haltstate)
        halt();
 
    if (THREAD) {
        spinlock_lock(&THREAD->lock);
        fpu_context_save(&(THREAD->saved_fpu_context));
        if (!context_save(&THREAD->saved_context)) {
            /*
             * This is the place where threads leave scheduler();
             */
            before_thread_runs();
            spinlock_unlock(&THREAD->lock);
            cpu_priority_restore(THREAD->saved_context.pri);
            return;
        }
 
        /*
         * CPU priority of preempted thread is recorded here
         * to facilitate scheduler() invocations from
         * cpu_priority_high()'ed code (e.g. waitq_sleep_timeout()).
         */
        THREAD->saved_context.pri = pri;
    }
 
    /*
     * Through the 'THE' structure, we keep track of THREAD, TASK, CPU
     * 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), 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.
 *
 */
void scheduler_separated_stack(void)
{
    int priority;
 
    if (THREAD) {
        switch (THREAD->state) {
            case Running:
            THREAD->state = Ready;
            spinlock_unlock(&THREAD->lock);
            thread_ready(THREAD);
            break;
 
            case Exiting:
            frame_free((__address) THREAD->kstack);
            if (THREAD->ustack) {
                frame_free((__address) THREAD->ustack);
            }
 
            /*
             * Detach from the containing task.
             */
            spinlock_lock(&TASK->lock);
            list_remove(&THREAD->th_link);
            spinlock_unlock(&TASK->lock);
 
            spinlock_unlock(&THREAD->lock);
   
            spinlock_lock(&threads_lock);
            list_remove(&THREAD->threads_link);
            spinlock_unlock(&threads_lock);
 
            spinlock_lock(&CPU->lock);
            if(CPU->fpu_owner==THREAD) CPU->fpu_owner=NULL;
            spinlock_unlock(&CPU->lock);
 
            free(THREAD);
 
            break;
   
            case Sleeping:
            /*
             * Prefer the thread after it's woken up.
             */
            THREAD->pri = -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;
    }
 
    printf("Ahoj");
    THREAD = find_best_thread();
//  putchar('@');
    printf("Lidi");
//  printf("*1*");
   
    spinlock_lock(&THREAD->lock);
    priority = THREAD->pri;
    spinlock_unlock(&THREAD->lock);
 
    relink_rq(priority);       
 
    spinlock_lock(&THREAD->lock);  
 
    /*
     * If both the old and the new task are the same, lots of work is avoided.
     */
    if (TASK != THREAD->task) {
        vm_t *m1 = NULL;
        vm_t *m2;
 
        if (TASK) {
            spinlock_lock(&TASK->lock);
            m1 = TASK->vm;
            spinlock_unlock(&TASK->lock);
        }
 
        spinlock_lock(&THREAD->task->lock);
        m2 = THREAD->task->vm;
        spinlock_unlock(&THREAD->task->lock);
       
        /*
         * Note that it is possible for two tasks to share one vm mapping.
         */
        if (m1 != m2) {
            /*
             * Both tasks and vm mappings are different.
             * Replace the old one with the new one.
             */
            vm_install(m2);
        }
        TASK = THREAD->task;   
    }
 
    THREAD->state = Running;
 
    #ifdef SCHEDULER_VERBOSE
    printf("cpu%d: tid %d (pri=%d,ticks=%d,nrdy=%d)\n", CPU->id, THREAD->tid, THREAD->pri, THREAD->ticks, CPU->nrdy);
    #endif  
 
    the_copy(THE, (the_t *) THREAD->kstack);
   
    context_restore(&THREAD->saved_context);
    /* not reached */
}
 
 
#ifdef __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, i, j, k = 0;
    pri_t pri;
 
loop:
    /*
     * Sleep until there's some work to do.
     */
    waitq_sleep(&CPU->kcpulb_wq);
 
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.
     */
    pri = cpu_priority_high();
    spinlock_lock(&CPU->lock);
    count = nrdy / config.cpu_active;
    count -= CPU->nrdy;
    spinlock_unlock(&CPU->lock);
    cpu_priority_restore(pri);
 
    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;              
 
restart:        pri = cpu_priority_high();
            r = &cpu->rq[j];
            spinlock_lock(&r->lock);
            if (r->n == 0) {
                spinlock_unlock(&r->lock);
                cpu_priority_restore(pri);
                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);
                   
                    /*
                     * Here we have to avoid deadlock with relink_rq(),
                     * because it locks cpu and r in a different order than we do.
                     */
                    if (!spinlock_trylock(&cpu->lock)) {
                        /* Release all locks and try again. */
                        spinlock_unlock(&r->lock);
                        cpu_priority_restore(pri);
                        goto restart;
                    }
                    cpu->nrdy--;
                    spinlock_unlock(&cpu->lock);
 
                    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=%d, avg=%d\n", CPU->id, t->tid, CPU->id, CPU->nrdy, nrdy / config.cpu_active);
                #endif
                t->flags |= X_STOLEN;
                spinlock_unlock(&t->lock);
   
                thread_ready(t);
 
                cpu_priority_restore(pri);
   
                if (--count == 0)
                    goto satisfied;
                   
                /*
                 * We are not satisfied yet, focus on another CPU next time.
                 */
                k++;
               
                continue;
            }
            cpu_priority_restore(pri);
        }
    }
 
    if (CPU->nrdy) {
        /*
         * Be a little bit light-weight and let migrated threads run.
         */
        scheduler();
    }
    else {
        /*
         * We failed to migrate a single thread.
         * Something more sophisticated should be done.
         */
        scheduler();
    }
       
    goto not_satisfied;
 
satisfied:
    /*
     * Tell find_best_thread() to wake us up later again.
     */
    CPU->kcpulbstarted = 0;
    goto loop;
}
 
#endif /* __SMP__ */
 

Rev 198	Rev 212
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	#include <proc/scheduler.h>	29	#include <proc/scheduler.h>
30	#include <proc/thread.h>	30	#include <proc/thread.h>
31	#include <proc/task.h>	31	#include <proc/task.h>
32	#include <cpu.h>	32	#include <cpu.h>
33	#include <mm/vm.h>	33	#include <mm/vm.h>
34	#include <config.h>	34	#include <config.h>
35	#include <context.h>	35	#include <context.h>
36	#include <func.h>	36	#include <func.h>
37	#include <arch.h>	37	#include <arch.h>
38	#include <arch/asm.h>	38	#include <arch/asm.h>
39	#include <list.h>	39	#include <list.h>
40	#include <panic.h>	40	#include <panic.h>
41	#include <typedefs.h>	41	#include <typedefs.h>
42	#include <mm/page.h>	42	#include <mm/page.h>
43	#include <synch/spinlock.h>	43	#include <synch/spinlock.h>
44	#include <arch/faddr.h>	44	#include <arch/faddr.h>
45	#include <arch/atomic.h>	45	#include <arch/atomic.h>
46	#include <print.h>	46	#include <print.h>
47	#include <mm/frame.h>	47	#include <mm/frame.h>
48	#include <mm/heap.h>	48	#include <mm/heap.h>
49		49
50		50
51	volatile int nrdy;	51	volatile int nrdy;
52		52
53		53
54	/** Take actions before new thread runs	54	/** Take actions before new thread runs
55	*	55	*
56	* Perform actions that need to be	56	* Perform actions that need to be
57	* taken before the newly selected	57	* taken before the newly selected
58	* tread is passed control.	58	* tread is passed control.
59	*	59	*
60	*/	60	*/
61	void before_thread_runs(void)	61	void before_thread_runs(void)
62	{	62	{
63	before_thread_runs_arch();	63	before_thread_runs_arch();
64	fpu_context_restore(&(THREAD->saved_fpu_context));	64	fpu_context_restore(&(THREAD->saved_fpu_context));
65	}	65	}
66		66
67		67
68	/** Initialize scheduler	68	/** Initialize scheduler
69	*	69	*
70	* Initialize kernel scheduler.	70	* Initialize kernel scheduler.
71	*	71	*
72	*/	72	*/
73	void scheduler_init(void)	73	void scheduler_init(void)
74	{	74	{
75	}	75	}
76		76
77		77
78	/** Get thread to be scheduled	78	/** Get thread to be scheduled
79	*	79	*
80	* Get the optimal thread to be scheduled	80	* Get the optimal thread to be scheduled
81	* according to thread accounting and scheduler	81	* according to thread accounting and scheduler
82	* policy.	82	* policy.
83	*	83	*
84	* @return Thread to be scheduled.	84	* @return Thread to be scheduled.
85	*	85	*
86	*/	86	*/
87	struct thread *find_best_thread(void)	87	struct thread *find_best_thread(void)
88	{	88	{
89	thread_t *t;	89	thread_t *t;
90	runq_t *r;	90	runq_t *r;
91	int i, n;	91	int i, n;
92		92
93	loop:	93	loop:
94	cpu_priority_high();	94	cpu_priority_high();
95		95
96	spinlock_lock(&CPU->lock);	96	spinlock_lock(&CPU->lock);
97	n = CPU->nrdy;	97	n = CPU->nrdy;
98	spinlock_unlock(&CPU->lock);	98	spinlock_unlock(&CPU->lock);
99		99
100	cpu_priority_low();	100	cpu_priority_low();
101		101
102	if (n == 0) {	102	if (n == 0) {
103	#ifdef __SMP__	103	#ifdef __SMP__
104	/*	104	/*
105	* If the load balancing thread is not running, wake it up and	105	* If the load balancing thread is not running, wake it up and
106	* set CPU-private flag that the kcpulb has been started.	106	* set CPU-private flag that the kcpulb has been started.
107	*/	107	*/
108	if (test_and_set(&CPU->kcpulbstarted) == 0) {	108	if (test_and_set(&CPU->kcpulbstarted) == 0) {
109	waitq_wakeup(&CPU->kcpulb_wq, 0);	109	waitq_wakeup(&CPU->kcpulb_wq, 0);
110	goto loop;	110	goto loop;
111	}	111	}
112	#endif /* __SMP__ */	112	#endif /* __SMP__ */
113		113
114	/*	114	/*
115	* For there was nothing to run, the CPU goes to sleep	115	* For there was nothing to run, the CPU goes to sleep
116	* until a hardware interrupt or an IPI comes.	116	* until a hardware interrupt or an IPI comes.
117	* This improves energy saving and hyperthreading.	117	* This improves energy saving and hyperthreading.
118	* On the other hand, several hardware interrupts can be ignored.	118	* On the other hand, several hardware interrupts can be ignored.
119	*/	119	*/
120	cpu_sleep();	120	cpu_sleep();
121	goto loop;	121	goto loop;
122	}	122	}
123		123
124	cpu_priority_high();	124	cpu_priority_high();
125		125
126	i = 0;	126	i = 0;
127	retry:	127	retry:
128	for (; i<RQ_COUNT; i++) {	128	for (; i<RQ_COUNT; i++) {
129	r = &CPU->rq[i];	129	r = &CPU->rq[i];
130	spinlock_lock(&r->lock);	130	spinlock_lock(&r->lock);
131	if (r->n == 0) {	131	if (r->n == 0) {
132	/*	132	/*
133	* If this queue is empty, try a lower-priority queue.	133	* If this queue is empty, try a lower-priority queue.
134	*/	134	*/
135	spinlock_unlock(&r->lock);	135	spinlock_unlock(&r->lock);
136	continue;	136	continue;
137	}	137	}
138		138
139	/* avoid deadlock with relink_rq() */	139	/* avoid deadlock with relink_rq() */
140	if (!spinlock_trylock(&CPU->lock)) {	140	if (!spinlock_trylock(&CPU->lock)) {
141	/*	141	/*
142	* Unlock r and try again.	142	* Unlock r and try again.
143	*/	143	*/
144	spinlock_unlock(&r->lock);	144	spinlock_unlock(&r->lock);
145	goto retry;	145	goto retry;
146	}	146	}
147	CPU->nrdy--;	147	CPU->nrdy--;
148	spinlock_unlock(&CPU->lock);	148	spinlock_unlock(&CPU->lock);
149		149
150	atomic_dec(&nrdy);	150	atomic_dec(&nrdy);
151	r->n--;	151	r->n--;
152		152
153	/*	153	/*
154	* Take the first thread from the queue.	154	* Take the first thread from the queue.
155	*/	155	*/
156	t = list_get_instance(r->rq_head.next, thread_t, rq_link);	156	t = list_get_instance(r->rq_head.next, thread_t, rq_link);
157	list_remove(&t->rq_link);	157	list_remove(&t->rq_link);
158		158
159	spinlock_unlock(&r->lock);	159	spinlock_unlock(&r->lock);
160		160
161	spinlock_lock(&t->lock);	161	spinlock_lock(&t->lock);
162	t->cpu = CPU;	162	t->cpu = CPU;
163		163
164	t->ticks = us2ticks((i+1)*10000);	164	t->ticks = us2ticks((i+1)*10000);
165	t->pri = i; /* eventually correct rq index */	165	t->pri = i; /* eventually correct rq index */
166		166
167	/*	167	/*
168	* Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge.	168	* Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge.
169	*/	169	*/
170	t->flags &= ~X_STOLEN;	170	t->flags &= ~X_STOLEN;
171	spinlock_unlock(&t->lock);	171	spinlock_unlock(&t->lock);
172		172
173	return t;	173	return t;
174	}	174	}
175	goto loop;	175	goto loop;
176		176
177	}	177	}
178		178
179		179
180	/** Prevent rq starvation	180	/** Prevent rq starvation
181	*	181	*
182	* Prevent low priority threads from starving in rq's.	182	* Prevent low priority threads from starving in rq's.
183	*	183	*
184	* When the function decides to relink rq's, it reconnects	184	* When the function decides to relink rq's, it reconnects
185	* respective pointers so that in result threads with 'pri'	185	* respective pointers so that in result threads with 'pri'
186	* greater or equal 'start' are moved to a higher-priority queue.	186	* greater or equal 'start' are moved to a higher-priority queue.
187	*	187	*
188	* @param start Threshold priority.	188	* @param start Threshold priority.
189	*	189	*
190	*/	190	*/
191	void relink_rq(int start)	191	void relink_rq(int start)
192	{	192	{
193	link_t head;	193	link_t head;
194	runq_t *r;	194	runq_t *r;
195	int i, n;	195	int i, n;
196		196
197	list_initialize(&head);	197	list_initialize(&head);
198	spinlock_lock(&CPU->lock);	198	spinlock_lock(&CPU->lock);
199	if (CPU->needs_relink > NEEDS_RELINK_MAX) {	199	if (CPU->needs_relink > NEEDS_RELINK_MAX) {
200	for (i = start; i<RQ_COUNT-1; i++) {	200	for (i = start; i<RQ_COUNT-1; i++) {
201	/* remember and empty rq[i + 1] */	201	/* remember and empty rq[i + 1] */
202	r = &CPU->rq[i + 1];	202	r = &CPU->rq[i + 1];
203	spinlock_lock(&r->lock);	203	spinlock_lock(&r->lock);
204	list_concat(&head, &r->rq_head);	204	list_concat(&head, &r->rq_head);
205	n = r->n;	205	n = r->n;
206	r->n = 0;	206	r->n = 0;
207	spinlock_unlock(&r->lock);	207	spinlock_unlock(&r->lock);
208		208
209	/* append rq[i + 1] to rq[i] */	209	/* append rq[i + 1] to rq[i] */
210	r = &CPU->rq[i];	210	r = &CPU->rq[i];
211	spinlock_lock(&r->lock);	211	spinlock_lock(&r->lock);
212	list_concat(&r->rq_head, &head);	212	list_concat(&r->rq_head, &head);
213	r->n += n;	213	r->n += n;
214	spinlock_unlock(&r->lock);	214	spinlock_unlock(&r->lock);
215	}	215	}
216	CPU->needs_relink = 0;	216	CPU->needs_relink = 0;
217	}	217	}
218	spinlock_unlock(&CPU->lock);	218	spinlock_unlock(&CPU->lock);
219		219
220	}	220	}
221		221
222		222
223	/** The scheduler	223	/** The scheduler
224	*	224	*
225	* The thread scheduling procedure.	225	* The thread scheduling procedure.
226	*	226	*
227	*/	227	*/
228	void scheduler(void)	228	void scheduler(void)
229	{	229	{
230	volatile pri_t pri;	230	volatile pri_t pri;
231		231
232	pri = cpu_priority_high();	232	pri = cpu_priority_high();
233		233
234	if (haltstate)	234	if (haltstate)
235	halt();	235	halt();
236		236
237	if (THREAD) {	237	if (THREAD) {
238	spinlock_lock(&THREAD->lock);	238	spinlock_lock(&THREAD->lock);
239	fpu_context_save(&(THREAD->saved_fpu_context));	239	fpu_context_save(&(THREAD->saved_fpu_context));
240	if (!context_save(&THREAD->saved_context)) {	240	if (!context_save(&THREAD->saved_context)) {
241	/*	241	/*
242	* This is the place where threads leave scheduler();	242	* This is the place where threads leave scheduler();
243	*/	243	*/
244	before_thread_runs();	244	before_thread_runs();
245	spinlock_unlock(&THREAD->lock);	245	spinlock_unlock(&THREAD->lock);
246	cpu_priority_restore(THREAD->saved_context.pri);	246	cpu_priority_restore(THREAD->saved_context.pri);
247	return;	247	return;
248	}	248	}
249		249
250	/*	250	/*
251	* CPU priority of preempted thread is recorded here	251	* CPU priority of preempted thread is recorded here
252	* to facilitate scheduler() invocations from	252	* to facilitate scheduler() invocations from
253	* cpu_priority_high()'ed code (e.g. waitq_sleep_timeout()).	253	* cpu_priority_high()'ed code (e.g. waitq_sleep_timeout()).
254	*/	254	*/
255	THREAD->saved_context.pri = pri;	255	THREAD->saved_context.pri = pri;
256	}	256	}
257		257
258	/*	258	/*
259	* Through the 'THE' structure, we keep track of THREAD, TASK, CPU	259	* Through the 'THE' structure, we keep track of THREAD, TASK, CPU
260	* and preemption counter. At this point THE could be coming either	260	* and preemption counter. At this point THE could be coming either
261	* from THREAD's or CPU's stack.	261	* from THREAD's or CPU's stack.
262	*/	262	*/
263	the_copy(THE, (the_t *) CPU->stack);	263	the_copy(THE, (the_t *) CPU->stack);
264		264
265	/*	265	/*
266	* We may not keep the old stack.	266	* We may not keep the old stack.
267	* Reason: If we kept the old stack and got blocked, for instance, in	267	* Reason: If we kept the old stack and got blocked, for instance, in
268	* find_best_thread(), the old thread could get rescheduled by another	268	* find_best_thread(), the old thread could get rescheduled by another
269	* CPU and overwrite the part of its own stack that was also used by	269	* CPU and overwrite the part of its own stack that was also used by
270	* the scheduler on this CPU.	270	* the scheduler on this CPU.
271	*	271	*
272	* Moreover, we have to bypass the compiler-generated POP sequence	272	* Moreover, we have to bypass the compiler-generated POP sequence
273	* which is fooled by SP being set to the very top of the stack.	273	* which is fooled by SP being set to the very top of the stack.
274	* Therefore the scheduler() function continues in	274	* Therefore the scheduler() function continues in
275	* scheduler_separated_stack().	275	* scheduler_separated_stack().
276	*/	276	*/
277	context_save(&CPU->saved_context);	277	context_save(&CPU->saved_context);
278	context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), CPU->stack, CPU_STACK_SIZE);	278	context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), CPU->stack, CPU_STACK_SIZE);
279	context_restore(&CPU->saved_context);	279	context_restore(&CPU->saved_context);
280	/* not reached */	280	/* not reached */
281	}	281	}
282		282
283		283
284	/** Scheduler stack switch wrapper	284	/** Scheduler stack switch wrapper
285	*	285	*
286	* Second part of the scheduler() function	286	* Second part of the scheduler() function
287	* using new stack. Handling the actual context	287	* using new stack. Handling the actual context
288	* switch to a new thread.	288	* switch to a new thread.
289	*	289	*
290	*/	290	*/
291	void scheduler_separated_stack(void)	291	void scheduler_separated_stack(void)
292	{	292	{
293	int priority;	293	int priority;
294		294
295	if (THREAD) {	295	if (THREAD) {
296	switch (THREAD->state) {	296	switch (THREAD->state) {
297	case Running:	297	case Running:
298	THREAD->state = Ready;	298	THREAD->state = Ready;
299	spinlock_unlock(&THREAD->lock);	299	spinlock_unlock(&THREAD->lock);
300	thread_ready(THREAD);	300	thread_ready(THREAD);
301	break;	301	break;
302		302
303	case Exiting:	303	case Exiting:
304	frame_free((__address) THREAD->kstack);	304	frame_free((__address) THREAD->kstack);
305	if (THREAD->ustack) {	305	if (THREAD->ustack) {
306	frame_free((__address) THREAD->ustack);	306	frame_free((__address) THREAD->ustack);
307	}	307	}
308		308
309	/*	309	/*
310	* Detach from the containing task.	310	* Detach from the containing task.
311	*/	311	*/
312	spinlock_lock(&TASK->lock);	312	spinlock_lock(&TASK->lock);
313	list_remove(&THREAD->th_link);	313	list_remove(&THREAD->th_link);
314	spinlock_unlock(&TASK->lock);	314	spinlock_unlock(&TASK->lock);
315		315
316	spinlock_unlock(&THREAD->lock);	316	spinlock_unlock(&THREAD->lock);
317		317
318	spinlock_lock(&threads_lock);	318	spinlock_lock(&threads_lock);
319	list_remove(&THREAD->threads_link);	319	list_remove(&THREAD->threads_link);
320	spinlock_unlock(&threads_lock);	320	spinlock_unlock(&threads_lock);
321		321
322	spinlock_lock(&CPU->lock);	322	spinlock_lock(&CPU->lock);
323	if(CPU->fpu_owner==THREAD) CPU->fpu_owner=NULL;	323	if(CPU->fpu_owner==THREAD) CPU->fpu_owner=NULL;
324	spinlock_unlock(&CPU->lock);	324	spinlock_unlock(&CPU->lock);
325		325
326	free(THREAD);	326	free(THREAD);
327		327
328	break;	328	break;
329		329
330	case Sleeping:	330	case Sleeping:
331	/*	331	/*
332	* Prefer the thread after it's woken up.	332	* Prefer the thread after it's woken up.
333	*/	333	*/
334	THREAD->pri = -1;	334	THREAD->pri = -1;
335		335
336	/*	336	/*
337	* We need to release wq->lock which we locked in waitq_sleep().	337	* We need to release wq->lock which we locked in waitq_sleep().
338	* Address of wq->lock is kept in THREAD->sleep_queue.	338	* Address of wq->lock is kept in THREAD->sleep_queue.
339	*/	339	*/
340	spinlock_unlock(&THREAD->sleep_queue->lock);	340	spinlock_unlock(&THREAD->sleep_queue->lock);
341		341
342	/*	342	/*
343	* Check for possible requests for out-of-context invocation.	343	* Check for possible requests for out-of-context invocation.
344	*/	344	*/
345	if (THREAD->call_me) {	345	if (THREAD->call_me) {
346	THREAD->call_me(THREAD->call_me_with);	346	THREAD->call_me(THREAD->call_me_with);
347	THREAD->call_me = NULL;	347	THREAD->call_me = NULL;
348	THREAD->call_me_with = NULL;	348	THREAD->call_me_with = NULL;
349	}	349	}
350		350
351	spinlock_unlock(&THREAD->lock);	351	spinlock_unlock(&THREAD->lock);
352		352
353	break;	353	break;
354		354
355	default:	355	default:
356	/*	356	/*
357	* Entering state is unexpected.	357	* Entering state is unexpected.
358	*/	358	*/
359	panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]);	359	panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]);
360	break;	360	break;
361	}	361	}
362	THREAD = NULL;	362	THREAD = NULL;
363	}	363	}
364		364
-		365	printf("Ahoj");
365	THREAD = find_best_thread();	366	THREAD = find_best_thread();
-		367	// putchar('@');
-		368	printf("Lidi");
-		369	// printf("1");
366		370
367	spinlock_lock(&THREAD->lock);	371	spinlock_lock(&THREAD->lock);
368	priority = THREAD->pri;	372	priority = THREAD->pri;
369	spinlock_unlock(&THREAD->lock);	373	spinlock_unlock(&THREAD->lock);
370		374
371	relink_rq(priority);	375	relink_rq(priority);
372		376
373	spinlock_lock(&THREAD->lock);	377	spinlock_lock(&THREAD->lock);
374		378
375	/*	379	/*
376	* If both the old and the new task are the same, lots of work is avoided.	380	* If both the old and the new task are the same, lots of work is avoided.
377	*/	381	*/
378	if (TASK != THREAD->task) {	382	if (TASK != THREAD->task) {
379	vm_t *m1 = NULL;	383	vm_t *m1 = NULL;
380	vm_t *m2;	384	vm_t *m2;
381		385
382	if (TASK) {	386	if (TASK) {
383	spinlock_lock(&TASK->lock);	387	spinlock_lock(&TASK->lock);
384	m1 = TASK->vm;	388	m1 = TASK->vm;
385	spinlock_unlock(&TASK->lock);	389	spinlock_unlock(&TASK->lock);
386	}	390	}
387		391
388	spinlock_lock(&THREAD->task->lock);	392	spinlock_lock(&THREAD->task->lock);
389	m2 = THREAD->task->vm;	393	m2 = THREAD->task->vm;
390	spinlock_unlock(&THREAD->task->lock);	394	spinlock_unlock(&THREAD->task->lock);
391		395
392	/*	396	/*
393	* Note that it is possible for two tasks to share one vm mapping.	397	* Note that it is possible for two tasks to share one vm mapping.
394	*/	398	*/
395	if (m1 != m2) {	399	if (m1 != m2) {
396	/*	400	/*
397	* Both tasks and vm mappings are different.	401	* Both tasks and vm mappings are different.
398	* Replace the old one with the new one.	402	* Replace the old one with the new one.
399	*/	403	*/
400	vm_install(m2);	404	vm_install(m2);
401	}	405	}
402	TASK = THREAD->task;	406	TASK = THREAD->task;
403	}	407	}
404		408
405	THREAD->state = Running;	409	THREAD->state = Running;
406		410
407	#ifdef SCHEDULER_VERBOSE	411	#ifdef SCHEDULER_VERBOSE
408	printf("cpu%d: tid %d (pri=%d,ticks=%d,nrdy=%d)\n", CPU->id, THREAD->tid, THREAD->pri, THREAD->ticks, CPU->nrdy);	412	printf("cpu%d: tid %d (pri=%d,ticks=%d,nrdy=%d)\n", CPU->id, THREAD->tid, THREAD->pri, THREAD->ticks, CPU->nrdy);
409	#endif	413	#endif
410		414
411	the_copy(THE, (the_t *) THREAD->kstack);	415	the_copy(THE, (the_t *) THREAD->kstack);
412		416
413	context_restore(&THREAD->saved_context);	417	context_restore(&THREAD->saved_context);
414	/* not reached */	418	/* not reached */
415	}	419	}
416		420
417		421
418	#ifdef __SMP__	422	#ifdef __SMP__
419	/** Load balancing thread	423	/** Load balancing thread
420	*	424	*
421	* SMP load balancing thread, supervising thread supplies	425	* SMP load balancing thread, supervising thread supplies
422	* for the CPU it's wired to.	426	* for the CPU it's wired to.
423	*	427	*
424	* @param arg Generic thread argument (unused).	428	* @param arg Generic thread argument (unused).
425	*	429	*
426	*/	430	*/
427	void kcpulb(void *arg)	431	void kcpulb(void *arg)
428	{	432	{
429	thread_t *t;	433	thread_t *t;
430	int count, i, j, k = 0;	434	int count, i, j, k = 0;
431	pri_t pri;	435	pri_t pri;
432		436
433	loop:	437	loop:
434	/*	438	/*
435	* Sleep until there's some work to do.	439	* Sleep until there's some work to do.
436	*/	440	*/
437	waitq_sleep(&CPU->kcpulb_wq);	441	waitq_sleep(&CPU->kcpulb_wq);
438		442
439	not_satisfied:	443	not_satisfied:
440	/*	444	/*
441	* Calculate the number of threads that will be migrated/stolen from	445	* Calculate the number of threads that will be migrated/stolen from
442	* other CPU's. Note that situation can have changed between two	446	* other CPU's. Note that situation can have changed between two
443	* passes. Each time get the most up to date counts.	447	* passes. Each time get the most up to date counts.
444	*/	448	*/
445	pri = cpu_priority_high();	449	pri = cpu_priority_high();
446	spinlock_lock(&CPU->lock);	450	spinlock_lock(&CPU->lock);
447	count = nrdy / config.cpu_active;	451	count = nrdy / config.cpu_active;
448	count -= CPU->nrdy;	452	count -= CPU->nrdy;
449	spinlock_unlock(&CPU->lock);	453	spinlock_unlock(&CPU->lock);
450	cpu_priority_restore(pri);	454	cpu_priority_restore(pri);
451		455
452	if (count <= 0)	456	if (count <= 0)
453	goto satisfied;	457	goto satisfied;
454		458
455	/*	459	/*
456	* Searching least priority queues on all CPU's first and most priority queues on all CPU's last.	460	* Searching least priority queues on all CPU's first and most priority queues on all CPU's last.
457	*/	461	*/
458	for (j=RQ_COUNT-1; j >= 0; j--) {	462	for (j=RQ_COUNT-1; j >= 0; j--) {
459	for (i=0; i < config.cpu_active; i++) {	463	for (i=0; i < config.cpu_active; i++) {
460	link_t *l;	464	link_t *l;
461	runq_t *r;	465	runq_t *r;
462	cpu_t *cpu;	466	cpu_t *cpu;
463		467
464	cpu = &cpus[(i + k) % config.cpu_active];	468	cpu = &cpus[(i + k) % config.cpu_active];
465		469
466	/*	470	/*
467	* Not interested in ourselves.	471	* Not interested in ourselves.
468	* Doesn't require interrupt disabling for kcpulb is X_WIRED.	472	* Doesn't require interrupt disabling for kcpulb is X_WIRED.
469	*/	473	*/
470	if (CPU == cpu)	474	if (CPU == cpu)
471	continue;	475	continue;
472		476
473	restart: pri = cpu_priority_high();	477	restart: pri = cpu_priority_high();
474	r = &cpu->rq[j];	478	r = &cpu->rq[j];
475	spinlock_lock(&r->lock);	479	spinlock_lock(&r->lock);
476	if (r->n == 0) {	480	if (r->n == 0) {
477	spinlock_unlock(&r->lock);	481	spinlock_unlock(&r->lock);
478	cpu_priority_restore(pri);	482	cpu_priority_restore(pri);
479	continue;	483	continue;
480	}	484	}
481		485
482	t = NULL;	486	t = NULL;
483	l = r->rq_head.prev; /* search rq from the back */	487	l = r->rq_head.prev; /* search rq from the back */
484	while (l != &r->rq_head) {	488	while (l != &r->rq_head) {
485	t = list_get_instance(l, thread_t, rq_link);	489	t = list_get_instance(l, thread_t, rq_link);
486	/*	490	/*
487	* We don't want to steal CPU-wired threads neither threads already stolen.	491	* We don't want to steal CPU-wired threads neither threads already stolen.
488	* The latter prevents threads from migrating between CPU's without ever being run.	492	* The latter prevents threads from migrating between CPU's without ever being run.
489	* We don't want to steal threads whose FPU context is still in CPU.	493	* We don't want to steal threads whose FPU context is still in CPU.
490	*/	494	*/
491	spinlock_lock(&t->lock);	495	spinlock_lock(&t->lock);
492	if ( (!(t->flags & (X_WIRED \| X_STOLEN))) && (!(t->fpu_context_engaged)) ) {	496	if ( (!(t->flags & (X_WIRED \| X_STOLEN))) && (!(t->fpu_context_engaged)) ) {
493		497
494	/*	498	/*
495	* Remove t from r.	499	* Remove t from r.
496	*/	500	*/

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/proc/scheduler.c @ 1705 – Rev 198 → 212