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