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Rev | Author | Line No. | Line |
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1 | jermar | 1 | /* |
2 | * Copyright (C) 2001-2004 Jakub Jermar |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | #include <proc/scheduler.h> |
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30 | #include <proc/thread.h> |
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31 | #include <proc/task.h> |
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32 | #include <cpu.h> |
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33 | #include <mm/vm.h> |
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34 | #include <config.h> |
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35 | #include <context.h> |
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36 | #include <func.h> |
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37 | #include <arch.h> |
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38 | #include <arch/asm.h> |
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39 | #include <list.h> |
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68 | decky | 40 | #include <panic.h> |
1 | jermar | 41 | #include <typedefs.h> |
42 | #include <mm/page.h> |
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43 | #include <synch/spinlock.h> |
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76 | jermar | 44 | #include <arch/faddr.h> |
111 | palkovsky | 45 | #include <arch/atomic.h> |
195 | vana | 46 | #include <print.h> |
47 | #include <mm/frame.h> |
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48 | #include <mm/heap.h> |
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227 | jermar | 49 | #include <debug.h> |
1 | jermar | 50 | |
227 | jermar | 51 | volatile count_t nrdy; |
195 | vana | 52 | |
1 | jermar | 53 | |
118 | jermar | 54 | /** Take actions before new thread runs |
107 | decky | 55 | * |
118 | jermar | 56 | * Perform actions that need to be |
57 | * taken before the newly selected |
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58 | * tread is passed control. |
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107 | decky | 59 | * |
60 | */ |
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52 | vana | 61 | void before_thread_runs(void) |
62 | { |
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309 | palkovsky | 63 | before_thread_runs_arch(); |
64 | #ifdef FPU_LAZY |
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65 | if(THREAD==CPU->fpu_owner) |
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66 | fpu_enable(); |
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67 | else |
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68 | fpu_disable(); |
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69 | #else |
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70 | fpu_enable(); |
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71 | if (THREAD->fpu_context_exists) |
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72 | fpu_context_restore(&(THREAD->saved_fpu_context)); |
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73 | else { |
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74 | fpu_init(); |
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75 | THREAD->fpu_context_exists=1; |
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76 | } |
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77 | #endif |
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52 | vana | 78 | } |
79 | |||
309 | palkovsky | 80 | #ifdef FPU_LAZY |
81 | void scheduler_fpu_lazy_request(void) |
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82 | { |
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83 | fpu_enable(); |
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84 | if (CPU->fpu_owner != NULL) { |
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85 | fpu_context_save(&CPU->fpu_owner->saved_fpu_context); |
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86 | /* don't prevent migration */ |
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87 | CPU->fpu_owner->fpu_context_engaged=0; |
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88 | } |
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89 | if (THREAD->fpu_context_exists) |
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90 | fpu_context_restore(&THREAD->saved_fpu_context); |
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91 | else { |
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92 | fpu_init(); |
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93 | THREAD->fpu_context_exists=1; |
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94 | } |
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95 | CPU->fpu_owner=THREAD; |
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96 | THREAD->fpu_context_engaged = 1; |
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97 | } |
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98 | #endif |
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52 | vana | 99 | |
107 | decky | 100 | /** Initialize scheduler |
101 | * |
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102 | * Initialize kernel scheduler. |
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103 | * |
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104 | */ |
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1 | jermar | 105 | void scheduler_init(void) |
106 | { |
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107 | } |
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108 | |||
107 | decky | 109 | |
110 | /** Get thread to be scheduled |
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111 | * |
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112 | * Get the optimal thread to be scheduled |
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109 | jermar | 113 | * according to thread accounting and scheduler |
107 | decky | 114 | * policy. |
115 | * |
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116 | * @return Thread to be scheduled. |
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117 | * |
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118 | */ |
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1 | jermar | 119 | struct thread *find_best_thread(void) |
120 | { |
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121 | thread_t *t; |
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122 | runq_t *r; |
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123 | int i, n; |
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124 | |||
227 | jermar | 125 | ASSERT(CPU != NULL); |
126 | |||
1 | jermar | 127 | loop: |
128 | cpu_priority_high(); |
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129 | |||
15 | jermar | 130 | spinlock_lock(&CPU->lock); |
131 | n = CPU->nrdy; |
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132 | spinlock_unlock(&CPU->lock); |
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1 | jermar | 133 | |
134 | cpu_priority_low(); |
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135 | |||
136 | if (n == 0) { |
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137 | #ifdef __SMP__ |
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138 | /* |
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139 | * If the load balancing thread is not running, wake it up and |
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140 | * set CPU-private flag that the kcpulb has been started. |
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141 | */ |
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15 | jermar | 142 | if (test_and_set(&CPU->kcpulbstarted) == 0) { |
125 | jermar | 143 | waitq_wakeup(&CPU->kcpulb_wq, 0); |
1 | jermar | 144 | goto loop; |
145 | } |
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146 | #endif /* __SMP__ */ |
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147 | |||
148 | /* |
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149 | * For there was nothing to run, the CPU goes to sleep |
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150 | * until a hardware interrupt or an IPI comes. |
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151 | * This improves energy saving and hyperthreading. |
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152 | * On the other hand, several hardware interrupts can be ignored. |
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153 | */ |
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154 | cpu_sleep(); |
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155 | goto loop; |
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156 | } |
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157 | |||
158 | cpu_priority_high(); |
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114 | jermar | 159 | |
160 | i = 0; |
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161 | retry: |
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162 | for (; i<RQ_COUNT; i++) { |
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15 | jermar | 163 | r = &CPU->rq[i]; |
1 | jermar | 164 | spinlock_lock(&r->lock); |
165 | if (r->n == 0) { |
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166 | /* |
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167 | * If this queue is empty, try a lower-priority queue. |
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168 | */ |
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169 | spinlock_unlock(&r->lock); |
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170 | continue; |
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171 | } |
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213 | jermar | 172 | |
115 | jermar | 173 | /* avoid deadlock with relink_rq() */ |
114 | jermar | 174 | if (!spinlock_trylock(&CPU->lock)) { |
175 | /* |
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176 | * Unlock r and try again. |
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177 | */ |
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178 | spinlock_unlock(&r->lock); |
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179 | goto retry; |
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180 | } |
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15 | jermar | 181 | CPU->nrdy--; |
182 | spinlock_unlock(&CPU->lock); |
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1 | jermar | 183 | |
248 | jermar | 184 | atomic_dec((int *) &nrdy); |
1 | jermar | 185 | r->n--; |
186 | |||
187 | /* |
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188 | * Take the first thread from the queue. |
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189 | */ |
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190 | t = list_get_instance(r->rq_head.next, thread_t, rq_link); |
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191 | list_remove(&t->rq_link); |
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192 | |||
193 | spinlock_unlock(&r->lock); |
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194 | |||
195 | spinlock_lock(&t->lock); |
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15 | jermar | 196 | t->cpu = CPU; |
1 | jermar | 197 | |
198 | t->ticks = us2ticks((i+1)*10000); |
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199 | t->pri = i; /* eventually correct rq index */ |
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200 | |||
201 | /* |
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202 | * Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge. |
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203 | */ |
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204 | t->flags &= ~X_STOLEN; |
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205 | spinlock_unlock(&t->lock); |
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206 | |||
207 | return t; |
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208 | } |
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209 | goto loop; |
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210 | |||
211 | } |
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212 | |||
107 | decky | 213 | |
214 | /** Prevent rq starvation |
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215 | * |
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216 | * Prevent low priority threads from starving in rq's. |
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217 | * |
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218 | * When the function decides to relink rq's, it reconnects |
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219 | * respective pointers so that in result threads with 'pri' |
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220 | * greater or equal 'start' are moved to a higher-priority queue. |
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221 | * |
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222 | * @param start Threshold priority. |
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223 | * |
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1 | jermar | 224 | */ |
225 | void relink_rq(int start) |
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226 | { |
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227 | link_t head; |
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228 | runq_t *r; |
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229 | int i, n; |
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230 | |||
231 | list_initialize(&head); |
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15 | jermar | 232 | spinlock_lock(&CPU->lock); |
233 | if (CPU->needs_relink > NEEDS_RELINK_MAX) { |
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1 | jermar | 234 | for (i = start; i<RQ_COUNT-1; i++) { |
235 | /* remember and empty rq[i + 1] */ |
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15 | jermar | 236 | r = &CPU->rq[i + 1]; |
1 | jermar | 237 | spinlock_lock(&r->lock); |
238 | list_concat(&head, &r->rq_head); |
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239 | n = r->n; |
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240 | r->n = 0; |
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241 | spinlock_unlock(&r->lock); |
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242 | |||
243 | /* append rq[i + 1] to rq[i] */ |
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15 | jermar | 244 | r = &CPU->rq[i]; |
1 | jermar | 245 | spinlock_lock(&r->lock); |
246 | list_concat(&r->rq_head, &head); |
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247 | r->n += n; |
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248 | spinlock_unlock(&r->lock); |
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249 | } |
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15 | jermar | 250 | CPU->needs_relink = 0; |
1 | jermar | 251 | } |
15 | jermar | 252 | spinlock_unlock(&CPU->lock); |
1 | jermar | 253 | |
254 | } |
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255 | |||
107 | decky | 256 | |
257 | /** The scheduler |
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258 | * |
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259 | * The thread scheduling procedure. |
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260 | * |
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1 | jermar | 261 | */ |
262 | void scheduler(void) |
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263 | { |
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264 | volatile pri_t pri; |
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265 | |||
227 | jermar | 266 | ASSERT(CPU != NULL); |
267 | |||
1 | jermar | 268 | pri = cpu_priority_high(); |
269 | |||
270 | if (haltstate) |
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271 | halt(); |
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272 | |||
15 | jermar | 273 | if (THREAD) { |
274 | spinlock_lock(&THREAD->lock); |
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309 | palkovsky | 275 | #ifndef FPU_LAZY |
57 | vana | 276 | fpu_context_save(&(THREAD->saved_fpu_context)); |
309 | palkovsky | 277 | #endif |
15 | jermar | 278 | if (!context_save(&THREAD->saved_context)) { |
1 | jermar | 279 | /* |
280 | * This is the place where threads leave scheduler(); |
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281 | */ |
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22 | jermar | 282 | before_thread_runs(); |
125 | jermar | 283 | spinlock_unlock(&THREAD->lock); |
15 | jermar | 284 | cpu_priority_restore(THREAD->saved_context.pri); |
1 | jermar | 285 | return; |
286 | } |
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170 | jermar | 287 | |
288 | /* |
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289 | * CPU priority of preempted thread is recorded here |
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290 | * to facilitate scheduler() invocations from |
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291 | * cpu_priority_high()'ed code (e.g. waitq_sleep_timeout()). |
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292 | */ |
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15 | jermar | 293 | THREAD->saved_context.pri = pri; |
1 | jermar | 294 | } |
295 | |||
296 | /* |
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184 | jermar | 297 | * Through the 'THE' structure, we keep track of THREAD, TASK, CPU |
298 | * and preemption counter. At this point THE could be coming either |
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299 | * from THREAD's or CPU's stack. |
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300 | */ |
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301 | the_copy(THE, (the_t *) CPU->stack); |
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302 | |||
303 | /* |
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1 | jermar | 304 | * We may not keep the old stack. |
305 | * Reason: If we kept the old stack and got blocked, for instance, in |
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306 | * find_best_thread(), the old thread could get rescheduled by another |
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307 | * CPU and overwrite the part of its own stack that was also used by |
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308 | * the scheduler on this CPU. |
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309 | * |
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310 | * Moreover, we have to bypass the compiler-generated POP sequence |
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311 | * which is fooled by SP being set to the very top of the stack. |
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312 | * Therefore the scheduler() function continues in |
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313 | * scheduler_separated_stack(). |
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314 | */ |
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15 | jermar | 315 | context_save(&CPU->saved_context); |
97 | jermar | 316 | context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), CPU->stack, CPU_STACK_SIZE); |
15 | jermar | 317 | context_restore(&CPU->saved_context); |
1 | jermar | 318 | /* not reached */ |
319 | } |
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320 | |||
107 | decky | 321 | |
322 | /** Scheduler stack switch wrapper |
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323 | * |
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324 | * Second part of the scheduler() function |
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325 | * using new stack. Handling the actual context |
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326 | * switch to a new thread. |
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327 | * |
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328 | */ |
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1 | jermar | 329 | void scheduler_separated_stack(void) |
330 | { |
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331 | int priority; |
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332 | |||
227 | jermar | 333 | ASSERT(CPU != NULL); |
334 | |||
15 | jermar | 335 | if (THREAD) { |
336 | switch (THREAD->state) { |
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1 | jermar | 337 | case Running: |
125 | jermar | 338 | THREAD->state = Ready; |
339 | spinlock_unlock(&THREAD->lock); |
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340 | thread_ready(THREAD); |
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341 | break; |
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1 | jermar | 342 | |
343 | case Exiting: |
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125 | jermar | 344 | frame_free((__address) THREAD->kstack); |
345 | if (THREAD->ustack) { |
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346 | frame_free((__address) THREAD->ustack); |
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347 | } |
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1 | jermar | 348 | |
125 | jermar | 349 | /* |
350 | * Detach from the containing task. |
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351 | */ |
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352 | spinlock_lock(&TASK->lock); |
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353 | list_remove(&THREAD->th_link); |
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354 | spinlock_unlock(&TASK->lock); |
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73 | vana | 355 | |
125 | jermar | 356 | spinlock_unlock(&THREAD->lock); |
357 | |||
358 | spinlock_lock(&threads_lock); |
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359 | list_remove(&THREAD->threads_link); |
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360 | spinlock_unlock(&threads_lock); |
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73 | vana | 361 | |
125 | jermar | 362 | spinlock_lock(&CPU->lock); |
363 | if(CPU->fpu_owner==THREAD) CPU->fpu_owner=NULL; |
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364 | spinlock_unlock(&CPU->lock); |
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365 | |||
366 | free(THREAD); |
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367 | |||
368 | break; |
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369 | |||
1 | jermar | 370 | case Sleeping: |
125 | jermar | 371 | /* |
372 | * Prefer the thread after it's woken up. |
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373 | */ |
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374 | THREAD->pri = -1; |
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1 | jermar | 375 | |
125 | jermar | 376 | /* |
377 | * We need to release wq->lock which we locked in waitq_sleep(). |
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378 | * Address of wq->lock is kept in THREAD->sleep_queue. |
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379 | */ |
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380 | spinlock_unlock(&THREAD->sleep_queue->lock); |
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1 | jermar | 381 | |
125 | jermar | 382 | /* |
383 | * Check for possible requests for out-of-context invocation. |
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384 | */ |
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385 | if (THREAD->call_me) { |
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386 | THREAD->call_me(THREAD->call_me_with); |
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387 | THREAD->call_me = NULL; |
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388 | THREAD->call_me_with = NULL; |
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389 | } |
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1 | jermar | 390 | |
125 | jermar | 391 | spinlock_unlock(&THREAD->lock); |
1 | jermar | 392 | |
125 | jermar | 393 | break; |
394 | |||
1 | jermar | 395 | default: |
125 | jermar | 396 | /* |
397 | * Entering state is unexpected. |
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398 | */ |
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399 | panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]); |
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400 | break; |
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1 | jermar | 401 | } |
15 | jermar | 402 | THREAD = NULL; |
1 | jermar | 403 | } |
198 | jermar | 404 | |
214 | vana | 405 | |
15 | jermar | 406 | THREAD = find_best_thread(); |
1 | jermar | 407 | |
15 | jermar | 408 | spinlock_lock(&THREAD->lock); |
409 | priority = THREAD->pri; |
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410 | spinlock_unlock(&THREAD->lock); |
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192 | jermar | 411 | |
1 | jermar | 412 | relink_rq(priority); |
413 | |||
15 | jermar | 414 | spinlock_lock(&THREAD->lock); |
1 | jermar | 415 | |
416 | /* |
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417 | * If both the old and the new task are the same, lots of work is avoided. |
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418 | */ |
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15 | jermar | 419 | if (TASK != THREAD->task) { |
1 | jermar | 420 | vm_t *m1 = NULL; |
421 | vm_t *m2; |
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422 | |||
15 | jermar | 423 | if (TASK) { |
424 | spinlock_lock(&TASK->lock); |
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425 | m1 = TASK->vm; |
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426 | spinlock_unlock(&TASK->lock); |
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1 | jermar | 427 | } |
428 | |||
15 | jermar | 429 | spinlock_lock(&THREAD->task->lock); |
430 | m2 = THREAD->task->vm; |
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431 | spinlock_unlock(&THREAD->task->lock); |
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1 | jermar | 432 | |
433 | /* |
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434 | * Note that it is possible for two tasks to share one vm mapping. |
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435 | */ |
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436 | if (m1 != m2) { |
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437 | /* |
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438 | * Both tasks and vm mappings are different. |
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439 | * Replace the old one with the new one. |
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440 | */ |
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441 | vm_install(m2); |
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442 | } |
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15 | jermar | 443 | TASK = THREAD->task; |
1 | jermar | 444 | } |
445 | |||
15 | jermar | 446 | THREAD->state = Running; |
1 | jermar | 447 | |
448 | #ifdef SCHEDULER_VERBOSE |
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15 | jermar | 449 | printf("cpu%d: tid %d (pri=%d,ticks=%d,nrdy=%d)\n", CPU->id, THREAD->tid, THREAD->pri, THREAD->ticks, CPU->nrdy); |
1 | jermar | 450 | #endif |
451 | |||
213 | jermar | 452 | /* |
453 | * Copy the knowledge of CPU, TASK, THREAD and preemption counter to thread's stack. |
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454 | */ |
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184 | jermar | 455 | the_copy(THE, (the_t *) THREAD->kstack); |
456 | |||
15 | jermar | 457 | context_restore(&THREAD->saved_context); |
1 | jermar | 458 | /* not reached */ |
459 | } |
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460 | |||
107 | decky | 461 | |
1 | jermar | 462 | #ifdef __SMP__ |
107 | decky | 463 | /** Load balancing thread |
464 | * |
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465 | * SMP load balancing thread, supervising thread supplies |
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466 | * for the CPU it's wired to. |
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467 | * |
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468 | * @param arg Generic thread argument (unused). |
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469 | * |
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1 | jermar | 470 | */ |
471 | void kcpulb(void *arg) |
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472 | { |
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473 | thread_t *t; |
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474 | int count, i, j, k = 0; |
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475 | pri_t pri; |
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476 | |||
477 | loop: |
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478 | /* |
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479 | * Sleep until there's some work to do. |
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480 | */ |
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15 | jermar | 481 | waitq_sleep(&CPU->kcpulb_wq); |
1 | jermar | 482 | |
483 | not_satisfied: |
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484 | /* |
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485 | * Calculate the number of threads that will be migrated/stolen from |
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486 | * other CPU's. Note that situation can have changed between two |
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487 | * passes. Each time get the most up to date counts. |
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488 | */ |
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489 | pri = cpu_priority_high(); |
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15 | jermar | 490 | spinlock_lock(&CPU->lock); |
1 | jermar | 491 | count = nrdy / config.cpu_active; |
15 | jermar | 492 | count -= CPU->nrdy; |
493 | spinlock_unlock(&CPU->lock); |
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1 | jermar | 494 | cpu_priority_restore(pri); |
495 | |||
496 | if (count <= 0) |
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497 | goto satisfied; |
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498 | |||
499 | /* |
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500 | * Searching least priority queues on all CPU's first and most priority queues on all CPU's last. |
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501 | */ |
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502 | for (j=RQ_COUNT-1; j >= 0; j--) { |
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503 | for (i=0; i < config.cpu_active; i++) { |
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504 | link_t *l; |
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505 | runq_t *r; |
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506 | cpu_t *cpu; |
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507 | |||
508 | cpu = &cpus[(i + k) % config.cpu_active]; |
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509 | |||
510 | /* |
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511 | * Not interested in ourselves. |
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512 | * Doesn't require interrupt disabling for kcpulb is X_WIRED. |
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513 | */ |
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15 | jermar | 514 | if (CPU == cpu) |
115 | jermar | 515 | continue; |
1 | jermar | 516 | |
517 | restart: pri = cpu_priority_high(); |
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115 | jermar | 518 | r = &cpu->rq[j]; |
1 | jermar | 519 | spinlock_lock(&r->lock); |
520 | if (r->n == 0) { |
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521 | spinlock_unlock(&r->lock); |
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522 | cpu_priority_restore(pri); |
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523 | continue; |
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524 | } |
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525 | |||
526 | t = NULL; |
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527 | l = r->rq_head.prev; /* search rq from the back */ |
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528 | while (l != &r->rq_head) { |
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529 | t = list_get_instance(l, thread_t, rq_link); |
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530 | /* |
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125 | jermar | 531 | * We don't want to steal CPU-wired threads neither threads already stolen. |
1 | jermar | 532 | * The latter prevents threads from migrating between CPU's without ever being run. |
125 | jermar | 533 | * We don't want to steal threads whose FPU context is still in CPU. |
73 | vana | 534 | */ |
1 | jermar | 535 | spinlock_lock(&t->lock); |
73 | vana | 536 | if ( (!(t->flags & (X_WIRED | X_STOLEN))) && (!(t->fpu_context_engaged)) ) { |
115 | jermar | 537 | |
1 | jermar | 538 | /* |
539 | * Remove t from r. |
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540 | */ |
||
541 | |||
542 | spinlock_unlock(&t->lock); |
||
543 | |||
544 | /* |
||
545 | * Here we have to avoid deadlock with relink_rq(), |
||
546 | * because it locks cpu and r in a different order than we do. |
||
547 | */ |
||
548 | if (!spinlock_trylock(&cpu->lock)) { |
||
549 | /* Release all locks and try again. */ |
||
550 | spinlock_unlock(&r->lock); |
||
551 | cpu_priority_restore(pri); |
||
552 | goto restart; |
||
553 | } |
||
554 | cpu->nrdy--; |
||
555 | spinlock_unlock(&cpu->lock); |
||
556 | |||
258 | palkovsky | 557 | atomic_dec((int *)&nrdy); |
1 | jermar | 558 | |
125 | jermar | 559 | r->n--; |
1 | jermar | 560 | list_remove(&t->rq_link); |
561 | |||
562 | break; |
||
563 | } |
||
564 | spinlock_unlock(&t->lock); |
||
565 | l = l->prev; |
||
566 | t = NULL; |
||
567 | } |
||
568 | spinlock_unlock(&r->lock); |
||
569 | |||
570 | if (t) { |
||
571 | /* |
||
572 | * Ready t on local CPU |
||
573 | */ |
||
574 | spinlock_lock(&t->lock); |
||
575 | #ifdef KCPULB_VERBOSE |
||
15 | jermar | 576 | printf("kcpulb%d: TID %d -> cpu%d, nrdy=%d, avg=%d\n", CPU->id, t->tid, CPU->id, CPU->nrdy, nrdy / config.cpu_active); |
1 | jermar | 577 | #endif |
578 | t->flags |= X_STOLEN; |
||
579 | spinlock_unlock(&t->lock); |
||
580 | |||
581 | thread_ready(t); |
||
582 | |||
583 | cpu_priority_restore(pri); |
||
584 | |||
585 | if (--count == 0) |
||
586 | goto satisfied; |
||
587 | |||
588 | /* |
||
125 | jermar | 589 | * We are not satisfied yet, focus on another CPU next time. |
1 | jermar | 590 | */ |
591 | k++; |
||
592 | |||
593 | continue; |
||
594 | } |
||
595 | cpu_priority_restore(pri); |
||
596 | } |
||
597 | } |
||
598 | |||
15 | jermar | 599 | if (CPU->nrdy) { |
1 | jermar | 600 | /* |
601 | * Be a little bit light-weight and let migrated threads run. |
||
602 | */ |
||
603 | scheduler(); |
||
604 | } |
||
605 | else { |
||
606 | /* |
||
607 | * We failed to migrate a single thread. |
||
608 | * Something more sophisticated should be done. |
||
609 | */ |
||
610 | scheduler(); |
||
611 | } |
||
612 | |||
613 | goto not_satisfied; |
||
125 | jermar | 614 | |
1 | jermar | 615 | satisfied: |
616 | /* |
||
617 | * Tell find_best_thread() to wake us up later again. |
||
618 | */ |
||
15 | jermar | 619 | CPU->kcpulbstarted = 0; |
1 | jermar | 620 | goto loop; |
621 | } |
||
622 | |||
623 | #endif /* __SMP__ */ |