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  1. /*
  2.  * Copyright (C) 2001-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  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
  15.  *   derived from this software without specific prior written permission.
  16.  *
  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
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  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
  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
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup genericproc
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief   Scheduler and load balancing.
  36.  *
  37.  * This file contains the scheduler and kcpulb kernel thread which
  38.  * performs load-balancing of per-CPU run queues.
  39.  */
  40.  
  41. #include <proc/scheduler.h>
  42. #include <proc/thread.h>
  43. #include <proc/task.h>
  44. #include <mm/frame.h>
  45. #include <mm/page.h>
  46. #include <mm/as.h>
  47. #include <time/delay.h>
  48. #include <arch/asm.h>
  49. #include <arch/faddr.h>
  50. #include <arch/cycle.h>
  51. #include <atomic.h>
  52. #include <synch/spinlock.h>
  53. #include <config.h>
  54. #include <context.h>
  55. #include <func.h>
  56. #include <arch.h>
  57. #include <adt/list.h>
  58. #include <panic.h>
  59. #include <typedefs.h>
  60. #include <cpu.h>
  61. #include <print.h>
  62. #include <debug.h>
  63.  
  64. static void before_task_runs(void);
  65. static void before_thread_runs(void);
  66. static void after_thread_ran(void);
  67. static void scheduler_separated_stack(void);
  68.  
  69. atomic_t nrdy;  /**< Number of ready threads in the system. */
  70.  
  71. /** Carry out actions before new task runs. */
  72. void before_task_runs(void)
  73. {
  74.     before_task_runs_arch();
  75. }
  76.  
  77. /** Take actions before new thread runs.
  78.  *
  79.  * Perform actions that need to be
  80.  * taken before the newly selected
  81.  * tread is passed control.
  82.  *
  83.  * THREAD->lock is locked on entry
  84.  *
  85.  */
  86. void before_thread_runs(void)
  87. {
  88.     before_thread_runs_arch();
  89. #ifdef CONFIG_FPU_LAZY
  90.     if(THREAD == CPU->fpu_owner)
  91.         fpu_enable();
  92.     else
  93.         fpu_disable();
  94. #else
  95.     fpu_enable();
  96.     if (THREAD->fpu_context_exists)
  97.         fpu_context_restore(THREAD->saved_fpu_context);
  98.     else {
  99.         fpu_init();
  100.         THREAD->fpu_context_exists = 1;
  101.     }
  102. #endif
  103. }
  104.  
  105. /** Take actions after THREAD had run.
  106.  *
  107.  * Perform actions that need to be
  108.  * taken after the running thread
  109.  * had been preempted by the scheduler.
  110.  *
  111.  * THREAD->lock is locked on entry
  112.  *
  113.  */
  114. void after_thread_ran(void)
  115. {
  116.     after_thread_ran_arch();
  117. }
  118.  
  119. #ifdef CONFIG_FPU_LAZY
  120. void scheduler_fpu_lazy_request(void)
  121. {
  122. restart:
  123.     fpu_enable();
  124.     spinlock_lock(&CPU->lock);
  125.  
  126.     /* Save old context */
  127.     if (CPU->fpu_owner != NULL) {  
  128.         spinlock_lock(&CPU->fpu_owner->lock);
  129.         fpu_context_save(CPU->fpu_owner->saved_fpu_context);
  130.         /* don't prevent migration */
  131.         CPU->fpu_owner->fpu_context_engaged = 0;
  132.         spinlock_unlock(&CPU->fpu_owner->lock);
  133.         CPU->fpu_owner = NULL;
  134.     }
  135.  
  136.     spinlock_lock(&THREAD->lock);
  137.     if (THREAD->fpu_context_exists) {
  138.         fpu_context_restore(THREAD->saved_fpu_context);
  139.     } else {
  140.         /* Allocate FPU context */
  141.         if (!THREAD->saved_fpu_context) {
  142.             /* Might sleep */
  143.             spinlock_unlock(&THREAD->lock);
  144.             spinlock_unlock(&CPU->lock);
  145.             THREAD->saved_fpu_context = slab_alloc(fpu_context_slab, 0);
  146.             /* We may have switched CPUs during slab_alloc */
  147.             goto restart;
  148.         }
  149.         fpu_init();
  150.         THREAD->fpu_context_exists = 1;
  151.     }
  152.     CPU->fpu_owner = THREAD;
  153.     THREAD->fpu_context_engaged = 1;
  154.     spinlock_unlock(&THREAD->lock);
  155.  
  156.     spinlock_unlock(&CPU->lock);
  157. }
  158. #endif
  159.  
  160. /** Initialize scheduler
  161.  *
  162.  * Initialize kernel scheduler.
  163.  *
  164.  */
  165. void scheduler_init(void)
  166. {
  167. }
  168.  
  169. /** Get thread to be scheduled
  170.  *
  171.  * Get the optimal thread to be scheduled
  172.  * according to thread accounting and scheduler
  173.  * policy.
  174.  *
  175.  * @return Thread to be scheduled.
  176.  *
  177.  */
  178. static thread_t *find_best_thread(void)
  179. {
  180.     thread_t *t;
  181.     runq_t *r;
  182.     int i;
  183.  
  184.     ASSERT(CPU != NULL);
  185.  
  186. loop:
  187.     interrupts_enable();
  188.    
  189.     if (atomic_get(&CPU->nrdy) == 0) {
  190.         /*
  191.          * For there was nothing to run, the CPU goes to sleep
  192.          * until a hardware interrupt or an IPI comes.
  193.          * This improves energy saving and hyperthreading.
  194.          */
  195.  
  196.         /*
  197.          * An interrupt might occur right now and wake up a thread.
  198.          * In such case, the CPU will continue to go to sleep
  199.          * even though there is a runnable thread.
  200.          */
  201.  
  202.          cpu_sleep();
  203.          goto loop;
  204.     }
  205.  
  206.     interrupts_disable();
  207.    
  208.     for (i = 0; i<RQ_COUNT; i++) {
  209.         r = &CPU->rq[i];
  210.         spinlock_lock(&r->lock);
  211.         if (r->n == 0) {
  212.             /*
  213.              * If this queue is empty, try a lower-priority queue.
  214.              */
  215.             spinlock_unlock(&r->lock);
  216.             continue;
  217.         }
  218.  
  219.         atomic_dec(&CPU->nrdy);
  220.         atomic_dec(&nrdy);
  221.         r->n--;
  222.  
  223.         /*
  224.          * Take the first thread from the queue.
  225.          */
  226.         t = list_get_instance(r->rq_head.next, thread_t, rq_link);
  227.         list_remove(&t->rq_link);
  228.  
  229.         spinlock_unlock(&r->lock);
  230.  
  231.         spinlock_lock(&t->lock);
  232.         t->cpu = CPU;
  233.  
  234.         t->ticks = us2ticks((i+1)*10000);
  235.         t->priority = i;    /* correct rq index */
  236.  
  237.         /*
  238.          * Clear the THREAD_FLAG_STOLEN flag so that t can be migrated
  239.          * when load balancing needs emerge.
  240.          */
  241.         t->flags &= ~THREAD_FLAG_STOLEN;
  242.         spinlock_unlock(&t->lock);
  243.  
  244.         return t;
  245.     }
  246.     goto loop;
  247.  
  248. }
  249.  
  250. /** Prevent rq starvation
  251.  *
  252.  * Prevent low priority threads from starving in rq's.
  253.  *
  254.  * When the function decides to relink rq's, it reconnects
  255.  * respective pointers so that in result threads with 'pri'
  256.  * greater or equal start are moved to a higher-priority queue.
  257.  *
  258.  * @param start Threshold priority.
  259.  *
  260.  */
  261. static void relink_rq(int start)
  262. {
  263.     link_t head;
  264.     runq_t *r;
  265.     int i, n;
  266.  
  267.     list_initialize(&head);
  268.     spinlock_lock(&CPU->lock);
  269.     if (CPU->needs_relink > NEEDS_RELINK_MAX) {
  270.         for (i = start; i<RQ_COUNT-1; i++) {
  271.             /* remember and empty rq[i + 1] */
  272.             r = &CPU->rq[i + 1];
  273.             spinlock_lock(&r->lock);
  274.             list_concat(&head, &r->rq_head);
  275.             n = r->n;
  276.             r->n = 0;
  277.             spinlock_unlock(&r->lock);
  278.        
  279.             /* append rq[i + 1] to rq[i] */
  280.             r = &CPU->rq[i];
  281.             spinlock_lock(&r->lock);
  282.             list_concat(&r->rq_head, &head);
  283.             r->n += n;
  284.             spinlock_unlock(&r->lock);
  285.         }
  286.         CPU->needs_relink = 0;
  287.     }
  288.     spinlock_unlock(&CPU->lock);
  289.  
  290. }
  291.  
  292. /** The scheduler
  293.  *
  294.  * The thread scheduling procedure.
  295.  * Passes control directly to
  296.  * scheduler_separated_stack().
  297.  *
  298.  */
  299. void scheduler(void)
  300. {
  301.     volatile ipl_t ipl;
  302.  
  303.     ASSERT(CPU != NULL);
  304.  
  305.     ipl = interrupts_disable();
  306.  
  307.     if (atomic_get(&haltstate))
  308.         halt();
  309.    
  310.     if (THREAD) {
  311.         spinlock_lock(&THREAD->lock);
  312.        
  313.         /* Update thread accounting */
  314.         THREAD->cycles += get_cycle() - THREAD->last_cycle;
  315.        
  316. #ifndef CONFIG_FPU_LAZY
  317.         fpu_context_save(THREAD->saved_fpu_context);
  318. #endif
  319.         if (!context_save(&THREAD->saved_context)) {
  320.             /*
  321.              * This is the place where threads leave scheduler();
  322.              */
  323.            
  324.             /* Save current CPU cycle */
  325.             THREAD->last_cycle = get_cycle();
  326.            
  327.             spinlock_unlock(&THREAD->lock);
  328.             interrupts_restore(THREAD->saved_context.ipl);
  329.            
  330.             return;
  331.         }
  332.  
  333.         /*
  334.          * Interrupt priority level of preempted thread is recorded here
  335.          * to facilitate scheduler() invocations from interrupts_disable()'d
  336.          * code (e.g. waitq_sleep_timeout()).
  337.          */
  338.         THREAD->saved_context.ipl = ipl;
  339.     }
  340.  
  341.     /*
  342.      * Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM
  343.      * and preemption counter. At this point THE could be coming either
  344.      * from THREAD's or CPU's stack.
  345.      */
  346.     the_copy(THE, (the_t *) CPU->stack);
  347.  
  348.     /*
  349.      * We may not keep the old stack.
  350.      * Reason: If we kept the old stack and got blocked, for instance, in
  351.      * find_best_thread(), the old thread could get rescheduled by another
  352.      * CPU and overwrite the part of its own stack that was also used by
  353.      * the scheduler on this CPU.
  354.      *
  355.      * Moreover, we have to bypass the compiler-generated POP sequence
  356.      * which is fooled by SP being set to the very top of the stack.
  357.      * Therefore the scheduler() function continues in
  358.      * scheduler_separated_stack().
  359.      */
  360.     context_save(&CPU->saved_context);
  361.     context_set(&CPU->saved_context, FADDR(scheduler_separated_stack),
  362.         (uintptr_t) CPU->stack, CPU_STACK_SIZE);
  363.     context_restore(&CPU->saved_context);
  364.     /* not reached */
  365. }
  366.  
  367. /** Scheduler stack switch wrapper
  368.  *
  369.  * Second part of the scheduler() function
  370.  * using new stack. Handling the actual context
  371.  * switch to a new thread.
  372.  *
  373.  * Assume THREAD->lock is held.
  374.  */
  375. void scheduler_separated_stack(void)
  376. {
  377.     int priority;
  378.    
  379.     ASSERT(CPU != NULL);
  380.    
  381.     if (THREAD) {
  382.         /* must be run after the switch to scheduler stack */
  383.         after_thread_ran();
  384.  
  385.         switch (THREAD->state) {
  386.         case Running:
  387.             spinlock_unlock(&THREAD->lock);
  388.             thread_ready(THREAD);
  389.             break;
  390.  
  391.         case Exiting:
  392. repeat:
  393.                 if (THREAD->detached) {
  394.                 thread_destroy(THREAD);
  395.             } else {
  396.                 /*
  397.                  * The thread structure is kept allocated until somebody
  398.                  * calls thread_detach() on it.
  399.                  */
  400.                 if (!spinlock_trylock(&THREAD->join_wq.lock)) {
  401.                     /*
  402.                      * Avoid deadlock.
  403.                      */
  404.                     spinlock_unlock(&THREAD->lock);
  405.                     delay(10);
  406.                     spinlock_lock(&THREAD->lock);
  407.                     goto repeat;
  408.                 }
  409.                 _waitq_wakeup_unsafe(&THREAD->join_wq, false);
  410.                 spinlock_unlock(&THREAD->join_wq.lock);
  411.                
  412.                 THREAD->state = Undead;
  413.                 spinlock_unlock(&THREAD->lock);
  414.             }
  415.             break;
  416.            
  417.         case Sleeping:
  418.             /*
  419.              * Prefer the thread after it's woken up.
  420.              */
  421.             THREAD->priority = -1;
  422.  
  423.             /*
  424.              * We need to release wq->lock which we locked in waitq_sleep().
  425.              * Address of wq->lock is kept in THREAD->sleep_queue.
  426.              */
  427.             spinlock_unlock(&THREAD->sleep_queue->lock);
  428.  
  429.             /*
  430.              * Check for possible requests for out-of-context invocation.
  431.              */
  432.             if (THREAD->call_me) {
  433.                 THREAD->call_me(THREAD->call_me_with);
  434.                 THREAD->call_me = NULL;
  435.                 THREAD->call_me_with = NULL;
  436.             }
  437.  
  438.             spinlock_unlock(&THREAD->lock);
  439.  
  440.             break;
  441.  
  442.         default:
  443.             /*
  444.              * Entering state is unexpected.
  445.              */
  446.             panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]);
  447.             break;
  448.         }
  449.  
  450.         THREAD = NULL;
  451.     }
  452.  
  453.     THREAD = find_best_thread();
  454.    
  455.     spinlock_lock(&THREAD->lock);
  456.     priority = THREAD->priority;
  457.     spinlock_unlock(&THREAD->lock);
  458.  
  459.     relink_rq(priority);       
  460.  
  461.     /*
  462.      * If both the old and the new task are the same, lots of work is avoided.
  463.      */
  464.     if (TASK != THREAD->task) {
  465.         as_t *as1 = NULL;
  466.         as_t *as2;
  467.  
  468.         if (TASK) {
  469.             spinlock_lock(&TASK->lock);
  470.             as1 = TASK->as;
  471.             spinlock_unlock(&TASK->lock);
  472.         }
  473.  
  474.         spinlock_lock(&THREAD->task->lock);
  475.         as2 = THREAD->task->as;
  476.         spinlock_unlock(&THREAD->task->lock);
  477.        
  478.         /*
  479.          * Note that it is possible for two tasks to share one address space.
  480.          */
  481.         if (as1 != as2) {
  482.             /*
  483.              * Both tasks and address spaces are different.
  484.              * Replace the old one with the new one.
  485.              */
  486.             as_switch(as1, as2);
  487.         }
  488.         TASK = THREAD->task;
  489.         before_task_runs();
  490.     }
  491.  
  492.     spinlock_lock(&THREAD->lock);  
  493.     THREAD->state = Running;
  494.  
  495. #ifdef SCHEDULER_VERBOSE
  496.     printf("cpu%d: tid %d (priority=%d,ticks=%lld,nrdy=%ld)\n",
  497.         CPU->id, THREAD->tid, THREAD->priority, THREAD->ticks, atomic_get(&CPU->nrdy));
  498. #endif 
  499.  
  500.     /*
  501.      * Some architectures provide late kernel PA2KA(identity)
  502.      * mapping in a page fault handler. However, the page fault
  503.      * handler uses the kernel stack of the running thread and
  504.      * therefore cannot be used to map it. The kernel stack, if
  505.      * necessary, is to be mapped in before_thread_runs(). This
  506.      * function must be executed before the switch to the new stack.
  507.      */
  508.     before_thread_runs();
  509.  
  510.     /*
  511.      * Copy the knowledge of CPU, TASK, THREAD and preemption counter to thread's stack.
  512.      */
  513.     the_copy(THE, (the_t *) THREAD->kstack);
  514.    
  515.     context_restore(&THREAD->saved_context);
  516.     /* not reached */
  517. }
  518.  
  519. #ifdef CONFIG_SMP
  520. /** Load balancing thread
  521.  *
  522.  * SMP load balancing thread, supervising thread supplies
  523.  * for the CPU it's wired to.
  524.  *
  525.  * @param arg Generic thread argument (unused).
  526.  *
  527.  */
  528. void kcpulb(void *arg)
  529. {
  530.     thread_t *t;
  531.     int count, average, i, j, k = 0;
  532.     ipl_t ipl;
  533.  
  534.     /*
  535.      * Detach kcpulb as nobody will call thread_join_timeout() on it.
  536.      */
  537.     thread_detach(THREAD);
  538.    
  539. loop:
  540.     /*
  541.      * Work in 1s intervals.
  542.      */
  543.     thread_sleep(1);
  544.  
  545. not_satisfied:
  546.     /*
  547.      * Calculate the number of threads that will be migrated/stolen from
  548.      * other CPU's. Note that situation can have changed between two
  549.      * passes. Each time get the most up to date counts.
  550.      */
  551.     average = atomic_get(&nrdy) / config.cpu_active + 1;
  552.     count = average - atomic_get(&CPU->nrdy);
  553.  
  554.     if (count <= 0)
  555.         goto satisfied;
  556.  
  557.     /*
  558.      * Searching least priority queues on all CPU's first and most priority queues on all CPU's last.
  559.      */
  560.     for (j=RQ_COUNT-1; j >= 0; j--) {
  561.         for (i=0; i < config.cpu_active; i++) {
  562.             link_t *l;
  563.             runq_t *r;
  564.             cpu_t *cpu;
  565.  
  566.             cpu = &cpus[(i + k) % config.cpu_active];
  567.  
  568.             /*
  569.              * Not interested in ourselves.
  570.              * Doesn't require interrupt disabling for kcpulb has THREAD_FLAG_WIRED.
  571.              */
  572.             if (CPU == cpu)
  573.                 continue;
  574.             if (atomic_get(&cpu->nrdy) <= average)
  575.                 continue;
  576.  
  577.             ipl = interrupts_disable();
  578.             r = &cpu->rq[j];
  579.             spinlock_lock(&r->lock);
  580.             if (r->n == 0) {
  581.                 spinlock_unlock(&r->lock);
  582.                 interrupts_restore(ipl);
  583.                 continue;
  584.             }
  585.        
  586.             t = NULL;
  587.             l = r->rq_head.prev;    /* search rq from the back */
  588.             while (l != &r->rq_head) {
  589.                 t = list_get_instance(l, thread_t, rq_link);
  590.                 /*
  591.                  * We don't want to steal CPU-wired threads neither threads already
  592.                  * stolen. The latter prevents threads from migrating between CPU's
  593.                  * without ever being run. We don't want to steal threads whose FPU
  594.                  * context is still in CPU.
  595.                  */
  596.                 spinlock_lock(&t->lock);
  597.                 if ((!(t->flags & (THREAD_FLAG_WIRED | THREAD_FLAG_STOLEN))) &&
  598.                     (!(t->fpu_context_engaged)) ) {
  599.                     /*
  600.                      * Remove t from r.
  601.                      */
  602.                     spinlock_unlock(&t->lock);
  603.                    
  604.                     atomic_dec(&cpu->nrdy);
  605.                     atomic_dec(&nrdy);
  606.  
  607.                     r->n--;
  608.                     list_remove(&t->rq_link);
  609.  
  610.                     break;
  611.                 }
  612.                 spinlock_unlock(&t->lock);
  613.                 l = l->prev;
  614.                 t = NULL;
  615.             }
  616.             spinlock_unlock(&r->lock);
  617.  
  618.             if (t) {
  619.                 /*
  620.                  * Ready t on local CPU
  621.                  */
  622.                 spinlock_lock(&t->lock);
  623. #ifdef KCPULB_VERBOSE
  624.                 printf("kcpulb%d: TID %d -> cpu%d, nrdy=%ld, avg=%nd\n",
  625.                     CPU->id, t->tid, CPU->id, atomic_get(&CPU->nrdy),
  626.                     atomic_get(&nrdy) / config.cpu_active);
  627. #endif
  628.                 t->flags |= THREAD_FLAG_STOLEN;
  629.                 t->state = Entering;
  630.                 spinlock_unlock(&t->lock);
  631.    
  632.                 thread_ready(t);
  633.  
  634.                 interrupts_restore(ipl);
  635.    
  636.                 if (--count == 0)
  637.                     goto satisfied;
  638.                    
  639.                 /*
  640.                  * We are not satisfied yet, focus on another CPU next time.
  641.                  */
  642.                 k++;
  643.                
  644.                 continue;
  645.             }
  646.             interrupts_restore(ipl);
  647.         }
  648.     }
  649.  
  650.     if (atomic_get(&CPU->nrdy)) {
  651.         /*
  652.          * Be a little bit light-weight and let migrated threads run.
  653.          */
  654.         scheduler();
  655.     } else {
  656.         /*
  657.          * We failed to migrate a single thread.
  658.          * Give up this turn.
  659.          */
  660.         goto loop;
  661.     }
  662.        
  663.     goto not_satisfied;
  664.  
  665. satisfied:
  666.     goto loop;
  667. }
  668.  
  669. #endif /* CONFIG_SMP */
  670.  
  671.  
  672. /** Print information about threads & scheduler queues */
  673. void sched_print_list(void)
  674. {
  675.     ipl_t ipl;
  676.     int cpu,i;
  677.     runq_t *r;
  678.     thread_t *t;
  679.     link_t *cur;
  680.  
  681.     /* We are going to mess with scheduler structures,
  682.      * let's not be interrupted */
  683.     ipl = interrupts_disable();
  684.     for (cpu=0;cpu < config.cpu_count; cpu++) {
  685.  
  686.         if (!cpus[cpu].active)
  687.             continue;
  688.  
  689.         spinlock_lock(&cpus[cpu].lock);
  690.         printf("cpu%d: address=%p, nrdy=%ld, needs_relink=%ld\n",
  691.                cpus[cpu].id, &cpus[cpu], atomic_get(&cpus[cpu].nrdy), cpus[cpu].needs_relink);
  692.        
  693.         for (i=0; i<RQ_COUNT; i++) {
  694.             r = &cpus[cpu].rq[i];
  695.             spinlock_lock(&r->lock);
  696.             if (!r->n) {
  697.                 spinlock_unlock(&r->lock);
  698.                 continue;
  699.             }
  700.             printf("\trq[%d]: ", i);
  701.             for (cur=r->rq_head.next; cur!=&r->rq_head; cur=cur->next) {
  702.                 t = list_get_instance(cur, thread_t, rq_link);
  703.                 printf("%d(%s) ", t->tid,
  704.                        thread_states[t->state]);
  705.             }
  706.             printf("\n");
  707.             spinlock_unlock(&r->lock);
  708.         }
  709.         spinlock_unlock(&cpus[cpu].lock);
  710.     }
  711.    
  712.     interrupts_restore(ipl);
  713. }
  714.  
  715. /** @}
  716.  */
  717.