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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 <mm/heap.h> |
32 | #include <mm/heap.h> |
33 | #include <mm/frame.h> |
33 | #include <mm/frame.h> |
34 | #include <mm/page.h> |
34 | #include <mm/page.h> |
35 | #include <mm/vm.h> |
35 | #include <mm/vm.h> |
36 | #include <arch/asm.h> |
36 | #include <arch/asm.h> |
37 | #include <arch/faddr.h> |
37 | #include <arch/faddr.h> |
38 | #include <arch/atomic.h> |
38 | #include <arch/atomic.h> |
39 | #include <synch/spinlock.h> |
39 | #include <synch/spinlock.h> |
40 | #include <config.h> |
40 | #include <config.h> |
41 | #include <context.h> |
41 | #include <context.h> |
42 | #include <func.h> |
42 | #include <func.h> |
43 | #include <arch.h> |
43 | #include <arch.h> |
44 | #include <list.h> |
44 | #include <list.h> |
45 | #include <panic.h> |
45 | #include <panic.h> |
46 | #include <typedefs.h> |
46 | #include <typedefs.h> |
47 | #include <cpu.h> |
47 | #include <cpu.h> |
48 | #include <print.h> |
48 | #include <print.h> |
49 | #include <debug.h> |
49 | #include <debug.h> |
50 | 50 | ||
51 | atomic_t nrdy; |
51 | atomic_t nrdy; |
52 | 52 | ||
53 | /** Take actions before new thread runs |
53 | /** Take actions before new thread runs |
54 | * |
54 | * |
55 | * Perform actions that need to be |
55 | * Perform actions that need to be |
56 | * taken before the newly selected |
56 | * taken before the newly selected |
57 | * tread is passed control. |
57 | * tread is passed control. |
58 | * |
58 | * |
59 | */ |
59 | */ |
60 | void before_thread_runs(void) |
60 | void before_thread_runs(void) |
61 | { |
61 | { |
62 | before_thread_runs_arch(); |
62 | before_thread_runs_arch(); |
63 | #ifdef CONFIG_FPU_LAZY |
63 | #ifdef CONFIG_FPU_LAZY |
64 | if(THREAD==CPU->fpu_owner) |
64 | if(THREAD==CPU->fpu_owner) |
65 | fpu_enable(); |
65 | fpu_enable(); |
66 | else |
66 | else |
67 | fpu_disable(); |
67 | fpu_disable(); |
68 | #else |
68 | #else |
69 | fpu_enable(); |
69 | fpu_enable(); |
70 | if (THREAD->fpu_context_exists) |
70 | if (THREAD->fpu_context_exists) |
71 | fpu_context_restore(&(THREAD->saved_fpu_context)); |
71 | fpu_context_restore(&(THREAD->saved_fpu_context)); |
72 | else { |
72 | else { |
73 | fpu_init(); |
73 | fpu_init(); |
74 | THREAD->fpu_context_exists=1; |
74 | THREAD->fpu_context_exists=1; |
75 | } |
75 | } |
76 | #endif |
76 | #endif |
77 | } |
77 | } |
78 | 78 | ||
79 | #ifdef CONFIG_FPU_LAZY |
79 | #ifdef CONFIG_FPU_LAZY |
80 | void scheduler_fpu_lazy_request(void) |
80 | void scheduler_fpu_lazy_request(void) |
81 | { |
81 | { |
82 | fpu_enable(); |
82 | fpu_enable(); |
83 | if (CPU->fpu_owner != NULL) { |
83 | if (CPU->fpu_owner != NULL) { |
84 | fpu_context_save(&CPU->fpu_owner->saved_fpu_context); |
84 | fpu_context_save(&CPU->fpu_owner->saved_fpu_context); |
85 | /* don't prevent migration */ |
85 | /* don't prevent migration */ |
86 | CPU->fpu_owner->fpu_context_engaged=0; |
86 | CPU->fpu_owner->fpu_context_engaged=0; |
87 | } |
87 | } |
88 | if (THREAD->fpu_context_exists) |
88 | if (THREAD->fpu_context_exists) |
89 | fpu_context_restore(&THREAD->saved_fpu_context); |
89 | fpu_context_restore(&THREAD->saved_fpu_context); |
90 | else { |
90 | else { |
91 | fpu_init(); |
91 | fpu_init(); |
92 | THREAD->fpu_context_exists=1; |
92 | THREAD->fpu_context_exists=1; |
93 | } |
93 | } |
94 | CPU->fpu_owner=THREAD; |
94 | CPU->fpu_owner=THREAD; |
95 | THREAD->fpu_context_engaged = 1; |
95 | THREAD->fpu_context_engaged = 1; |
96 | } |
96 | } |
97 | #endif |
97 | #endif |
98 | 98 | ||
99 | /** Initialize scheduler |
99 | /** Initialize scheduler |
100 | * |
100 | * |
101 | * Initialize kernel scheduler. |
101 | * Initialize kernel scheduler. |
102 | * |
102 | * |
103 | */ |
103 | */ |
104 | void scheduler_init(void) |
104 | void scheduler_init(void) |
105 | { |
105 | { |
106 | } |
106 | } |
107 | 107 | ||
108 | 108 | ||
109 | /** Get thread to be scheduled |
109 | /** Get thread to be scheduled |
110 | * |
110 | * |
111 | * Get the optimal thread to be scheduled |
111 | * Get the optimal thread to be scheduled |
112 | * according to thread accounting and scheduler |
112 | * according to thread accounting and scheduler |
113 | * policy. |
113 | * policy. |
114 | * |
114 | * |
115 | * @return Thread to be scheduled. |
115 | * @return Thread to be scheduled. |
116 | * |
116 | * |
117 | */ |
117 | */ |
118 | static thread_t *find_best_thread(void) |
118 | static thread_t *find_best_thread(void) |
119 | { |
119 | { |
120 | thread_t *t; |
120 | thread_t *t; |
121 | runq_t *r; |
121 | runq_t *r; |
122 | int i, n; |
122 | int i, n; |
123 | 123 | ||
124 | ASSERT(CPU != NULL); |
124 | ASSERT(CPU != NULL); |
125 | 125 | ||
126 | loop: |
126 | loop: |
127 | interrupts_disable(); |
127 | interrupts_disable(); |
128 | 128 | ||
129 | spinlock_lock(&CPU->lock); |
129 | spinlock_lock(&CPU->lock); |
130 | n = CPU->nrdy; |
130 | n = CPU->nrdy; |
131 | spinlock_unlock(&CPU->lock); |
131 | spinlock_unlock(&CPU->lock); |
132 | 132 | ||
133 | interrupts_enable(); |
133 | interrupts_enable(); |
134 | 134 | ||
135 | if (n == 0) { |
135 | if (n == 0) { |
136 | #ifdef CONFIG_SMP |
136 | #ifdef CONFIG_SMP |
137 | /* |
137 | /* |
138 | * If the load balancing thread is not running, wake it up and |
138 | * If the load balancing thread is not running, wake it up and |
139 | * set CPU-private flag that the kcpulb has been started. |
139 | * set CPU-private flag that the kcpulb has been started. |
140 | */ |
140 | */ |
141 | if (test_and_set(&CPU->kcpulbstarted) == 0) { |
141 | if (test_and_set(&CPU->kcpulbstarted) == 0) { |
142 | waitq_wakeup(&CPU->kcpulb_wq, 0); |
142 | waitq_wakeup(&CPU->kcpulb_wq, 0); |
143 | goto loop; |
143 | goto loop; |
144 | } |
144 | } |
145 | #endif /* CONFIG_SMP */ |
145 | #endif /* CONFIG_SMP */ |
146 | 146 | ||
147 | /* |
147 | /* |
148 | * For there was nothing to run, the CPU goes to sleep |
148 | * For there was nothing to run, the CPU goes to sleep |
149 | * until a hardware interrupt or an IPI comes. |
149 | * until a hardware interrupt or an IPI comes. |
150 | * This improves energy saving and hyperthreading. |
150 | * This improves energy saving and hyperthreading. |
151 | * On the other hand, several hardware interrupts can be ignored. |
151 | * On the other hand, several hardware interrupts can be ignored. |
152 | */ |
152 | */ |
153 | cpu_sleep(); |
153 | cpu_sleep(); |
154 | goto loop; |
154 | goto loop; |
155 | } |
155 | } |
156 | 156 | ||
157 | interrupts_disable(); |
157 | interrupts_disable(); |
158 | 158 | ||
159 | i = 0; |
159 | i = 0; |
160 | retry: |
160 | retry: |
161 | for (; i<RQ_COUNT; i++) { |
161 | for (; i<RQ_COUNT; i++) { |
162 | r = &CPU->rq[i]; |
162 | r = &CPU->rq[i]; |
163 | spinlock_lock(&r->lock); |
163 | spinlock_lock(&r->lock); |
164 | if (r->n == 0) { |
164 | if (r->n == 0) { |
165 | /* |
165 | /* |
166 | * If this queue is empty, try a lower-priority queue. |
166 | * If this queue is empty, try a lower-priority queue. |
167 | */ |
167 | */ |
168 | spinlock_unlock(&r->lock); |
168 | spinlock_unlock(&r->lock); |
169 | continue; |
169 | continue; |
170 | } |
170 | } |
171 | 171 | ||
172 | /* avoid deadlock with relink_rq() */ |
172 | /* avoid deadlock with relink_rq() */ |
173 | if (!spinlock_trylock(&CPU->lock)) { |
173 | if (!spinlock_trylock(&CPU->lock)) { |
174 | /* |
174 | /* |
175 | * Unlock r and try again. |
175 | * Unlock r and try again. |
176 | */ |
176 | */ |
177 | spinlock_unlock(&r->lock); |
177 | spinlock_unlock(&r->lock); |
178 | goto retry; |
178 | goto retry; |
179 | } |
179 | } |
180 | CPU->nrdy--; |
180 | CPU->nrdy--; |
181 | spinlock_unlock(&CPU->lock); |
181 | spinlock_unlock(&CPU->lock); |
182 | 182 | ||
183 | atomic_dec(&nrdy); |
183 | atomic_dec(&nrdy); |
184 | r->n--; |
184 | r->n--; |
185 | 185 | ||
186 | /* |
186 | /* |
187 | * Take the first thread from the queue. |
187 | * Take the first thread from the queue. |
188 | */ |
188 | */ |
189 | t = list_get_instance(r->rq_head.next, thread_t, rq_link); |
189 | t = list_get_instance(r->rq_head.next, thread_t, rq_link); |
190 | list_remove(&t->rq_link); |
190 | list_remove(&t->rq_link); |
191 | 191 | ||
192 | spinlock_unlock(&r->lock); |
192 | spinlock_unlock(&r->lock); |
193 | 193 | ||
194 | spinlock_lock(&t->lock); |
194 | spinlock_lock(&t->lock); |
195 | t->cpu = CPU; |
195 | t->cpu = CPU; |
196 | 196 | ||
197 | t->ticks = us2ticks((i+1)*10000); |
197 | t->ticks = us2ticks((i+1)*10000); |
198 | t->priority = i; /* eventually correct rq index */ |
198 | t->priority = i; /* eventually correct rq index */ |
199 | 199 | ||
200 | /* |
200 | /* |
201 | * Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge. |
201 | * Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge. |
202 | */ |
202 | */ |
203 | t->flags &= ~X_STOLEN; |
203 | t->flags &= ~X_STOLEN; |
204 | spinlock_unlock(&t->lock); |
204 | spinlock_unlock(&t->lock); |
205 | 205 | ||
206 | return t; |
206 | return t; |
207 | } |
207 | } |
208 | goto loop; |
208 | goto loop; |
209 | 209 | ||
210 | } |
210 | } |
211 | 211 | ||
212 | 212 | ||
213 | /** Prevent rq starvation |
213 | /** Prevent rq starvation |
214 | * |
214 | * |
215 | * Prevent low priority threads from starving in rq's. |
215 | * Prevent low priority threads from starving in rq's. |
216 | * |
216 | * |
217 | * When the function decides to relink rq's, it reconnects |
217 | * When the function decides to relink rq's, it reconnects |
218 | * respective pointers so that in result threads with 'pri' |
218 | * respective pointers so that in result threads with 'pri' |
219 | * greater or equal 'start' are moved to a higher-priority queue. |
219 | * greater or equal 'start' are moved to a higher-priority queue. |
220 | * |
220 | * |
221 | * @param start Threshold priority. |
221 | * @param start Threshold priority. |
222 | * |
222 | * |
223 | */ |
223 | */ |
224 | static void relink_rq(int start) |
224 | static void relink_rq(int start) |
225 | { |
225 | { |
226 | link_t head; |
226 | link_t head; |
227 | runq_t *r; |
227 | runq_t *r; |
228 | int i, n; |
228 | int i, n; |
229 | 229 | ||
230 | list_initialize(&head); |
230 | list_initialize(&head); |
231 | spinlock_lock(&CPU->lock); |
231 | spinlock_lock(&CPU->lock); |
232 | if (CPU->needs_relink > NEEDS_RELINK_MAX) { |
232 | if (CPU->needs_relink > NEEDS_RELINK_MAX) { |
233 | for (i = start; i<RQ_COUNT-1; i++) { |
233 | for (i = start; i<RQ_COUNT-1; i++) { |
234 | /* remember and empty rq[i + 1] */ |
234 | /* remember and empty rq[i + 1] */ |
235 | r = &CPU->rq[i + 1]; |
235 | r = &CPU->rq[i + 1]; |
236 | spinlock_lock(&r->lock); |
236 | spinlock_lock(&r->lock); |
237 | list_concat(&head, &r->rq_head); |
237 | list_concat(&head, &r->rq_head); |
238 | n = r->n; |
238 | n = r->n; |
239 | r->n = 0; |
239 | r->n = 0; |
240 | spinlock_unlock(&r->lock); |
240 | spinlock_unlock(&r->lock); |
241 | 241 | ||
242 | /* append rq[i + 1] to rq[i] */ |
242 | /* append rq[i + 1] to rq[i] */ |
243 | r = &CPU->rq[i]; |
243 | r = &CPU->rq[i]; |
244 | spinlock_lock(&r->lock); |
244 | spinlock_lock(&r->lock); |
245 | list_concat(&r->rq_head, &head); |
245 | list_concat(&r->rq_head, &head); |
246 | r->n += n; |
246 | r->n += n; |
247 | spinlock_unlock(&r->lock); |
247 | spinlock_unlock(&r->lock); |
248 | } |
248 | } |
249 | CPU->needs_relink = 0; |
249 | CPU->needs_relink = 0; |
250 | } |
250 | } |
251 | spinlock_unlock(&CPU->lock); |
251 | spinlock_unlock(&CPU->lock); |
252 | 252 | ||
253 | } |
253 | } |
254 | 254 | ||
255 | 255 | ||
256 | /** Scheduler stack switch wrapper |
256 | /** Scheduler stack switch wrapper |
257 | * |
257 | * |
258 | * Second part of the scheduler() function |
258 | * Second part of the scheduler() function |
259 | * using new stack. Handling the actual context |
259 | * using new stack. Handling the actual context |
260 | * switch to a new thread. |
260 | * switch to a new thread. |
261 | * |
261 | * |
262 | */ |
262 | */ |
263 | static void scheduler_separated_stack(void) |
263 | static void scheduler_separated_stack(void) |
264 | { |
264 | { |
265 | int priority; |
265 | int priority; |
266 | 266 | ||
267 | ASSERT(CPU != NULL); |
267 | ASSERT(CPU != NULL); |
268 | 268 | ||
269 | if (THREAD) { |
269 | if (THREAD) { |
270 | switch (THREAD->state) { |
270 | switch (THREAD->state) { |
271 | case Running: |
271 | case Running: |
272 | THREAD->state = Ready; |
272 | THREAD->state = Ready; |
273 | spinlock_unlock(&THREAD->lock); |
273 | spinlock_unlock(&THREAD->lock); |
274 | thread_ready(THREAD); |
274 | thread_ready(THREAD); |
275 | break; |
275 | break; |
276 | 276 | ||
277 | case Exiting: |
277 | case Exiting: |
278 | frame_free((__address) THREAD->kstack); |
278 | frame_free((__address) THREAD->kstack); |
279 | if (THREAD->ustack) { |
279 | if (THREAD->ustack) { |
280 | frame_free((__address) THREAD->ustack); |
280 | frame_free((__address) THREAD->ustack); |
281 | } |
281 | } |
282 | 282 | ||
283 | /* |
283 | /* |
284 | * Detach from the containing task. |
284 | * Detach from the containing task. |
285 | */ |
285 | */ |
286 | spinlock_lock(&TASK->lock); |
286 | spinlock_lock(&TASK->lock); |
287 | list_remove(&THREAD->th_link); |
287 | list_remove(&THREAD->th_link); |
288 | spinlock_unlock(&TASK->lock); |
288 | spinlock_unlock(&TASK->lock); |
289 | 289 | ||
290 | spinlock_unlock(&THREAD->lock); |
290 | spinlock_unlock(&THREAD->lock); |
291 | 291 | ||
292 | spinlock_lock(&threads_lock); |
292 | spinlock_lock(&threads_lock); |
293 | list_remove(&THREAD->threads_link); |
293 | list_remove(&THREAD->threads_link); |
294 | spinlock_unlock(&threads_lock); |
294 | spinlock_unlock(&threads_lock); |
295 | 295 | ||
296 | spinlock_lock(&CPU->lock); |
296 | spinlock_lock(&CPU->lock); |
297 | if(CPU->fpu_owner==THREAD) CPU->fpu_owner=NULL; |
297 | if(CPU->fpu_owner==THREAD) CPU->fpu_owner=NULL; |
298 | spinlock_unlock(&CPU->lock); |
298 | spinlock_unlock(&CPU->lock); |
299 | 299 | ||
300 | free(THREAD); |
300 | free(THREAD); |
301 | 301 | ||
302 | break; |
302 | break; |
303 | 303 | ||
304 | case Sleeping: |
304 | case Sleeping: |
305 | /* |
305 | /* |
306 | * Prefer the thread after it's woken up. |
306 | * Prefer the thread after it's woken up. |
307 | */ |
307 | */ |
308 | THREAD->priority = -1; |
308 | THREAD->priority = -1; |
309 | 309 | ||
310 | /* |
310 | /* |
311 | * We need to release wq->lock which we locked in waitq_sleep(). |
311 | * We need to release wq->lock which we locked in waitq_sleep(). |
312 | * Address of wq->lock is kept in THREAD->sleep_queue. |
312 | * Address of wq->lock is kept in THREAD->sleep_queue. |
313 | */ |
313 | */ |
314 | spinlock_unlock(&THREAD->sleep_queue->lock); |
314 | spinlock_unlock(&THREAD->sleep_queue->lock); |
315 | 315 | ||
316 | /* |
316 | /* |
317 | * Check for possible requests for out-of-context invocation. |
317 | * Check for possible requests for out-of-context invocation. |
318 | */ |
318 | */ |
319 | if (THREAD->call_me) { |
319 | if (THREAD->call_me) { |
320 | THREAD->call_me(THREAD->call_me_with); |
320 | THREAD->call_me(THREAD->call_me_with); |
321 | THREAD->call_me = NULL; |
321 | THREAD->call_me = NULL; |
322 | THREAD->call_me_with = NULL; |
322 | THREAD->call_me_with = NULL; |
323 | } |
323 | } |
324 | 324 | ||
325 | spinlock_unlock(&THREAD->lock); |
325 | spinlock_unlock(&THREAD->lock); |
326 | 326 | ||
327 | break; |
327 | break; |
328 | 328 | ||
329 | default: |
329 | default: |
330 | /* |
330 | /* |
331 | * Entering state is unexpected. |
331 | * Entering state is unexpected. |
332 | */ |
332 | */ |
333 | panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]); |
333 | panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]); |
334 | break; |
334 | break; |
335 | } |
335 | } |
336 | THREAD = NULL; |
336 | THREAD = NULL; |
337 | } |
337 | } |
338 | 338 | ||
339 | 339 | ||
340 | THREAD = find_best_thread(); |
340 | THREAD = find_best_thread(); |
341 | 341 | ||
342 | spinlock_lock(&THREAD->lock); |
342 | spinlock_lock(&THREAD->lock); |
343 | priority = THREAD->priority; |
343 | priority = THREAD->priority; |
344 | spinlock_unlock(&THREAD->lock); |
344 | spinlock_unlock(&THREAD->lock); |
345 | 345 | ||
346 | relink_rq(priority); |
346 | relink_rq(priority); |
347 | 347 | ||
348 | spinlock_lock(&THREAD->lock); |
348 | spinlock_lock(&THREAD->lock); |
349 | 349 | ||
350 | /* |
350 | /* |
351 | * If both the old and the new task are the same, lots of work is avoided. |
351 | * If both the old and the new task are the same, lots of work is avoided. |
352 | */ |
352 | */ |
353 | if (TASK != THREAD->task) { |
353 | if (TASK != THREAD->task) { |
354 | vm_t *m1 = NULL; |
354 | vm_t *m1 = NULL; |
355 | vm_t *m2; |
355 | vm_t *m2; |
356 | 356 | ||
357 | if (TASK) { |
357 | if (TASK) { |
358 | spinlock_lock(&TASK->lock); |
358 | spinlock_lock(&TASK->lock); |
359 | m1 = TASK->vm; |
359 | m1 = TASK->vm; |
360 | spinlock_unlock(&TASK->lock); |
360 | spinlock_unlock(&TASK->lock); |
361 | } |
361 | } |
362 | 362 | ||
363 | spinlock_lock(&THREAD->task->lock); |
363 | spinlock_lock(&THREAD->task->lock); |
364 | m2 = THREAD->task->vm; |
364 | m2 = THREAD->task->vm; |
365 | spinlock_unlock(&THREAD->task->lock); |
365 | spinlock_unlock(&THREAD->task->lock); |
366 | 366 | ||
367 | /* |
367 | /* |
368 | * Note that it is possible for two tasks to share one vm mapping. |
368 | * Note that it is possible for two tasks to share one vm mapping. |
369 | */ |
369 | */ |
370 | if (m1 != m2) { |
370 | if (m1 != m2) { |
371 | /* |
371 | /* |
372 | * Both tasks and vm mappings are different. |
372 | * Both tasks and vm mappings are different. |
373 | * Replace the old one with the new one. |
373 | * Replace the old one with the new one. |
374 | */ |
374 | */ |
375 | vm_install(m2); |
375 | vm_install(m2); |
376 | } |
376 | } |
377 | TASK = THREAD->task; |
377 | TASK = THREAD->task; |
378 | } |
378 | } |
379 | 379 | ||
380 | THREAD->state = Running; |
380 | THREAD->state = Running; |
381 | 381 | ||
382 | #ifdef SCHEDULER_VERBOSE |
382 | #ifdef SCHEDULER_VERBOSE |
383 | printf("cpu%d: tid %d (priority=%d,ticks=%d,nrdy=%d)\n", CPU->id, THREAD->tid, THREAD->priority, THREAD->ticks, CPU->nrdy); |
383 | printf("cpu%d: tid %d (priority=%d,ticks=%d,nrdy=%d)\n", CPU->id, THREAD->tid, THREAD->priority, THREAD->ticks, CPU->nrdy); |
384 | #endif |
384 | #endif |
385 | 385 | ||
386 | /* |
386 | /* |
387 | * Copy the knowledge of CPU, TASK, THREAD and preemption counter to thread's stack. |
387 | * Copy the knowledge of CPU, TASK, THREAD and preemption counter to thread's stack. |
388 | */ |
388 | */ |
389 | the_copy(THE, (the_t *) THREAD->kstack); |
389 | the_copy(THE, (the_t *) THREAD->kstack); |
390 | 390 | ||
391 | context_restore(&THREAD->saved_context); |
391 | context_restore(&THREAD->saved_context); |
392 | /* not reached */ |
392 | /* not reached */ |
393 | } |
393 | } |
394 | 394 | ||
395 | 395 | ||
396 | /** The scheduler |
396 | /** The scheduler |
397 | * |
397 | * |
398 | * The thread scheduling procedure. |
398 | * The thread scheduling procedure. |
399 | * |
399 | * |
400 | */ |
400 | */ |
401 | void scheduler(void) |
401 | void scheduler(void) |
402 | { |
402 | { |
403 | volatile ipl_t ipl; |
403 | volatile ipl_t ipl; |
404 | 404 | ||
405 | ASSERT(CPU != NULL); |
405 | ASSERT(CPU != NULL); |
406 | 406 | ||
407 | ipl = interrupts_disable(); |
407 | ipl = interrupts_disable(); |
408 | 408 | ||
409 | if (haltstate) |
409 | if (atomic_get(&haltstate)) |
410 | halt(); |
410 | halt(); |
411 | 411 | ||
412 | if (THREAD) { |
412 | if (THREAD) { |
413 | spinlock_lock(&THREAD->lock); |
413 | spinlock_lock(&THREAD->lock); |
414 | #ifndef CONFIG_FPU_LAZY |
414 | #ifndef CONFIG_FPU_LAZY |
415 | fpu_context_save(&(THREAD->saved_fpu_context)); |
415 | fpu_context_save(&(THREAD->saved_fpu_context)); |
416 | #endif |
416 | #endif |
417 | if (!context_save(&THREAD->saved_context)) { |
417 | if (!context_save(&THREAD->saved_context)) { |
418 | /* |
418 | /* |
419 | * This is the place where threads leave scheduler(); |
419 | * This is the place where threads leave scheduler(); |
420 | */ |
420 | */ |
421 | before_thread_runs(); |
421 | before_thread_runs(); |
422 | spinlock_unlock(&THREAD->lock); |
422 | spinlock_unlock(&THREAD->lock); |
423 | interrupts_restore(THREAD->saved_context.ipl); |
423 | interrupts_restore(THREAD->saved_context.ipl); |
424 | return; |
424 | return; |
425 | } |
425 | } |
426 | 426 | ||
427 | /* |
427 | /* |
428 | * Interrupt priority level of preempted thread is recorded here |
428 | * Interrupt priority level of preempted thread is recorded here |
429 | * to facilitate scheduler() invocations from interrupts_disable()'d |
429 | * to facilitate scheduler() invocations from interrupts_disable()'d |
430 | * code (e.g. waitq_sleep_timeout()). |
430 | * code (e.g. waitq_sleep_timeout()). |
431 | */ |
431 | */ |
432 | THREAD->saved_context.ipl = ipl; |
432 | THREAD->saved_context.ipl = ipl; |
433 | } |
433 | } |
434 | 434 | ||
435 | /* |
435 | /* |
436 | * Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM |
436 | * Through the 'THE' structure, we keep track of THREAD, TASK, CPU, VM |
437 | * and preemption counter. At this point THE could be coming either |
437 | * and preemption counter. At this point THE could be coming either |
438 | * from THREAD's or CPU's stack. |
438 | * from THREAD's or CPU's stack. |
439 | */ |
439 | */ |
440 | the_copy(THE, (the_t *) CPU->stack); |
440 | the_copy(THE, (the_t *) CPU->stack); |
441 | 441 | ||
442 | /* |
442 | /* |
443 | * We may not keep the old stack. |
443 | * We may not keep the old stack. |
444 | * Reason: If we kept the old stack and got blocked, for instance, in |
444 | * Reason: If we kept the old stack and got blocked, for instance, in |
445 | * find_best_thread(), the old thread could get rescheduled by another |
445 | * find_best_thread(), the old thread could get rescheduled by another |
446 | * CPU and overwrite the part of its own stack that was also used by |
446 | * CPU and overwrite the part of its own stack that was also used by |
447 | * the scheduler on this CPU. |
447 | * the scheduler on this CPU. |
448 | * |
448 | * |
449 | * Moreover, we have to bypass the compiler-generated POP sequence |
449 | * Moreover, we have to bypass the compiler-generated POP sequence |
450 | * which is fooled by SP being set to the very top of the stack. |
450 | * which is fooled by SP being set to the very top of the stack. |
451 | * Therefore the scheduler() function continues in |
451 | * Therefore the scheduler() function continues in |
452 | * scheduler_separated_stack(). |
452 | * scheduler_separated_stack(). |
453 | */ |
453 | */ |
454 | context_save(&CPU->saved_context); |
454 | context_save(&CPU->saved_context); |
455 | context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (__address) CPU->stack, CPU_STACK_SIZE); |
455 | context_set(&CPU->saved_context, FADDR(scheduler_separated_stack), (__address) CPU->stack, CPU_STACK_SIZE); |
456 | context_restore(&CPU->saved_context); |
456 | context_restore(&CPU->saved_context); |
457 | /* not reached */ |
457 | /* not reached */ |
458 | } |
458 | } |
459 | 459 | ||
460 | 460 | ||
461 | 461 | ||
462 | 462 | ||
463 | 463 | ||
464 | #ifdef CONFIG_SMP |
464 | #ifdef CONFIG_SMP |
465 | /** Load balancing thread |
465 | /** Load balancing thread |
466 | * |
466 | * |
467 | * SMP load balancing thread, supervising thread supplies |
467 | * SMP load balancing thread, supervising thread supplies |
468 | * for the CPU it's wired to. |
468 | * for the CPU it's wired to. |
469 | * |
469 | * |
470 | * @param arg Generic thread argument (unused). |
470 | * @param arg Generic thread argument (unused). |
471 | * |
471 | * |
472 | */ |
472 | */ |
473 | void kcpulb(void *arg) |
473 | void kcpulb(void *arg) |
474 | { |
474 | { |
475 | thread_t *t; |
475 | thread_t *t; |
476 | int count, i, j, k = 0; |
476 | int count, i, j, k = 0; |
477 | ipl_t ipl; |
477 | ipl_t ipl; |
478 | 478 | ||
479 | loop: |
479 | loop: |
480 | /* |
480 | /* |
481 | * Sleep until there's some work to do. |
481 | * Sleep until there's some work to do. |
482 | */ |
482 | */ |
483 | waitq_sleep(&CPU->kcpulb_wq); |
483 | waitq_sleep(&CPU->kcpulb_wq); |
484 | 484 | ||
485 | not_satisfied: |
485 | not_satisfied: |
486 | /* |
486 | /* |
487 | * Calculate the number of threads that will be migrated/stolen from |
487 | * Calculate the number of threads that will be migrated/stolen from |
488 | * other CPU's. Note that situation can have changed between two |
488 | * other CPU's. Note that situation can have changed between two |
489 | * passes. Each time get the most up to date counts. |
489 | * passes. Each time get the most up to date counts. |
490 | */ |
490 | */ |
491 | ipl = interrupts_disable(); |
491 | ipl = interrupts_disable(); |
492 | spinlock_lock(&CPU->lock); |
492 | spinlock_lock(&CPU->lock); |
493 | count = atomic_get(&nrdy) / config.cpu_active; |
493 | count = atomic_get(&nrdy) / config.cpu_active; |
494 | count -= CPU->nrdy; |
494 | count -= CPU->nrdy; |
495 | spinlock_unlock(&CPU->lock); |
495 | spinlock_unlock(&CPU->lock); |
496 | interrupts_restore(ipl); |
496 | interrupts_restore(ipl); |
497 | 497 | ||
498 | if (count <= 0) |
498 | if (count <= 0) |
499 | goto satisfied; |
499 | goto satisfied; |
500 | 500 | ||
501 | /* |
501 | /* |
502 | * Searching least priority queues on all CPU's first and most priority queues on all CPU's last. |
502 | * Searching least priority queues on all CPU's first and most priority queues on all CPU's last. |
503 | */ |
503 | */ |
504 | for (j=RQ_COUNT-1; j >= 0; j--) { |
504 | for (j=RQ_COUNT-1; j >= 0; j--) { |
505 | for (i=0; i < config.cpu_active; i++) { |
505 | for (i=0; i < config.cpu_active; i++) { |
506 | link_t *l; |
506 | link_t *l; |
507 | runq_t *r; |
507 | runq_t *r; |
508 | cpu_t *cpu; |
508 | cpu_t *cpu; |
509 | 509 | ||
510 | cpu = &cpus[(i + k) % config.cpu_active]; |
510 | cpu = &cpus[(i + k) % config.cpu_active]; |
511 | 511 | ||
512 | /* |
512 | /* |
513 | * Not interested in ourselves. |
513 | * Not interested in ourselves. |
514 | * Doesn't require interrupt disabling for kcpulb is X_WIRED. |
514 | * Doesn't require interrupt disabling for kcpulb is X_WIRED. |
515 | */ |
515 | */ |
516 | if (CPU == cpu) |
516 | if (CPU == cpu) |
517 | continue; |
517 | continue; |
518 | 518 | ||
519 | restart: ipl = interrupts_disable(); |
519 | restart: ipl = interrupts_disable(); |
520 | r = &cpu->rq[j]; |
520 | r = &cpu->rq[j]; |
521 | spinlock_lock(&r->lock); |
521 | spinlock_lock(&r->lock); |
522 | if (r->n == 0) { |
522 | if (r->n == 0) { |
523 | spinlock_unlock(&r->lock); |
523 | spinlock_unlock(&r->lock); |
524 | interrupts_restore(ipl); |
524 | interrupts_restore(ipl); |
525 | continue; |
525 | continue; |
526 | } |
526 | } |
527 | 527 | ||
528 | t = NULL; |
528 | t = NULL; |
529 | l = r->rq_head.prev; /* search rq from the back */ |
529 | l = r->rq_head.prev; /* search rq from the back */ |
530 | while (l != &r->rq_head) { |
530 | while (l != &r->rq_head) { |
531 | t = list_get_instance(l, thread_t, rq_link); |
531 | t = list_get_instance(l, thread_t, rq_link); |
532 | /* |
532 | /* |
533 | * We don't want to steal CPU-wired threads neither threads already stolen. |
533 | * We don't want to steal CPU-wired threads neither threads already stolen. |
534 | * The latter prevents threads from migrating between CPU's without ever being run. |
534 | * The latter prevents threads from migrating between CPU's without ever being run. |
535 | * We don't want to steal threads whose FPU context is still in CPU. |
535 | * We don't want to steal threads whose FPU context is still in CPU. |
536 | */ |
536 | */ |
537 | spinlock_lock(&t->lock); |
537 | spinlock_lock(&t->lock); |
538 | if ( (!(t->flags & (X_WIRED | X_STOLEN))) && (!(t->fpu_context_engaged)) ) { |
538 | if ( (!(t->flags & (X_WIRED | X_STOLEN))) && (!(t->fpu_context_engaged)) ) { |
539 | 539 | ||
540 | /* |
540 | /* |
541 | * Remove t from r. |
541 | * Remove t from r. |
542 | */ |
542 | */ |
543 | 543 | ||
544 | spinlock_unlock(&t->lock); |
544 | spinlock_unlock(&t->lock); |
545 | 545 | ||
546 | /* |
546 | /* |
547 | * Here we have to avoid deadlock with relink_rq(), |
547 | * Here we have to avoid deadlock with relink_rq(), |
548 | * because it locks cpu and r in a different order than we do. |
548 | * because it locks cpu and r in a different order than we do. |
549 | */ |
549 | */ |
550 | if (!spinlock_trylock(&cpu->lock)) { |
550 | if (!spinlock_trylock(&cpu->lock)) { |
551 | /* Release all locks and try again. */ |
551 | /* Release all locks and try again. */ |
552 | spinlock_unlock(&r->lock); |
552 | spinlock_unlock(&r->lock); |
553 | interrupts_restore(ipl); |
553 | interrupts_restore(ipl); |
554 | goto restart; |
554 | goto restart; |
555 | } |
555 | } |
556 | cpu->nrdy--; |
556 | cpu->nrdy--; |
557 | spinlock_unlock(&cpu->lock); |
557 | spinlock_unlock(&cpu->lock); |
558 | 558 | ||
559 | atomic_dec(&nrdy); |
559 | atomic_dec(&nrdy); |
560 | 560 | ||
561 | r->n--; |
561 | r->n--; |
562 | list_remove(&t->rq_link); |
562 | list_remove(&t->rq_link); |
563 | 563 | ||
564 | break; |
564 | break; |
565 | } |
565 | } |
566 | spinlock_unlock(&t->lock); |
566 | spinlock_unlock(&t->lock); |
567 | l = l->prev; |
567 | l = l->prev; |
568 | t = NULL; |
568 | t = NULL; |
569 | } |
569 | } |
570 | spinlock_unlock(&r->lock); |
570 | spinlock_unlock(&r->lock); |
571 | 571 | ||
572 | if (t) { |
572 | if (t) { |
573 | /* |
573 | /* |
574 | * Ready t on local CPU |
574 | * Ready t on local CPU |
575 | */ |
575 | */ |
576 | spinlock_lock(&t->lock); |
576 | spinlock_lock(&t->lock); |
577 | #ifdef KCPULB_VERBOSE |
577 | #ifdef KCPULB_VERBOSE |
578 | printf("kcpulb%d: TID %d -> cpu%d, nrdy=%d, avg=%d\n", CPU->id, t->tid, CPU->id, CPU->nrdy, nrdy / config.cpu_active); |
578 | printf("kcpulb%d: TID %d -> cpu%d, nrdy=%d, avg=%d\n", CPU->id, t->tid, CPU->id, CPU->nrdy, nrdy / config.cpu_active); |
579 | #endif |
579 | #endif |
580 | t->flags |= X_STOLEN; |
580 | t->flags |= X_STOLEN; |
581 | spinlock_unlock(&t->lock); |
581 | spinlock_unlock(&t->lock); |
582 | 582 | ||
583 | thread_ready(t); |
583 | thread_ready(t); |
584 | 584 | ||
585 | interrupts_restore(ipl); |
585 | interrupts_restore(ipl); |
586 | 586 | ||
587 | if (--count == 0) |
587 | if (--count == 0) |
588 | goto satisfied; |
588 | goto satisfied; |
589 | 589 | ||
590 | /* |
590 | /* |
591 | * We are not satisfied yet, focus on another CPU next time. |
591 | * We are not satisfied yet, focus on another CPU next time. |
592 | */ |
592 | */ |
593 | k++; |
593 | k++; |
594 | 594 | ||
595 | continue; |
595 | continue; |
596 | } |
596 | } |
597 | interrupts_restore(ipl); |
597 | interrupts_restore(ipl); |
598 | } |
598 | } |
599 | } |
599 | } |
600 | 600 | ||
601 | if (CPU->nrdy) { |
601 | if (CPU->nrdy) { |
602 | /* |
602 | /* |
603 | * Be a little bit light-weight and let migrated threads run. |
603 | * Be a little bit light-weight and let migrated threads run. |
604 | */ |
604 | */ |
605 | scheduler(); |
605 | scheduler(); |
606 | } |
606 | } |
607 | else { |
607 | else { |
608 | /* |
608 | /* |
609 | * We failed to migrate a single thread. |
609 | * We failed to migrate a single thread. |
610 | * Something more sophisticated should be done. |
610 | * Something more sophisticated should be done. |
611 | */ |
611 | */ |
612 | scheduler(); |
612 | scheduler(); |
613 | } |
613 | } |
614 | 614 | ||
615 | goto not_satisfied; |
615 | goto not_satisfied; |
616 | 616 | ||
617 | satisfied: |
617 | satisfied: |
618 | /* |
618 | /* |
619 | * Tell find_best_thread() to wake us up later again. |
619 | * Tell find_best_thread() to wake us up later again. |
620 | */ |
620 | */ |
621 | atomic_set(&CPU->kcpulbstarted,0); |
621 | atomic_set(&CPU->kcpulbstarted,0); |
622 | goto loop; |
622 | goto loop; |
623 | } |
623 | } |
624 | 624 | ||
625 | #endif /* CONFIG_SMP */ |
625 | #endif /* CONFIG_SMP */ |
626 | 626 |