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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 <cpu.h> |
32 | #include <cpu.h> |
33 | #include <mm/vm.h> |
33 | #include <mm/vm.h> |
34 | #include <config.h> |
34 | #include <config.h> |
35 | #include <context.h> |
35 | #include <context.h> |
36 | #include <func.h> |
36 | #include <func.h> |
37 | #include <arch.h> |
37 | #include <arch.h> |
38 | #include <arch/asm.h> |
38 | #include <arch/asm.h> |
39 | #include <list.h> |
39 | #include <list.h> |
40 | #include <typedefs.h> |
40 | #include <typedefs.h> |
41 | #include <mm/page.h> |
41 | #include <mm/page.h> |
42 | #include <synch/spinlock.h> |
42 | #include <synch/spinlock.h> |
43 | 43 | ||
44 | #ifdef __SMP__ |
44 | #ifdef __SMP__ |
45 | #include <arch/smp/atomic.h> |
45 | #include <arch/smp/atomic.h> |
46 | #endif /* __SMP__ */ |
46 | #endif /* __SMP__ */ |
47 | 47 | ||
48 | /* |
48 | /* |
49 | * NOTE ON ATOMIC READS: |
49 | * NOTE ON ATOMIC READS: |
50 | * Some architectures cannot read __u32 atomically. |
50 | * Some architectures cannot read __u32 atomically. |
51 | * For that reason, all accesses to nrdy and the likes must be protected by spinlock. |
51 | * For that reason, all accesses to nrdy and the likes must be protected by spinlock. |
52 | */ |
52 | */ |
53 | 53 | ||
54 | spinlock_t nrdylock; |
54 | spinlock_t nrdylock; |
55 | volatile int nrdy; |
55 | volatile int nrdy; |
56 | 56 | ||
- | 57 | void before_thread_runs(void) |
|
- | 58 | { |
|
- | 59 | before_thread_runs_arch(); |
|
- | 60 | fpu_context_restore(); |
|
- | 61 | } |
|
- | 62 | ||
- | 63 | ||
57 | void scheduler_init(void) |
64 | void scheduler_init(void) |
58 | { |
65 | { |
59 | spinlock_initialize(&nrdylock); |
66 | spinlock_initialize(&nrdylock); |
60 | } |
67 | } |
61 | 68 | ||
62 | /* cpu_priority_high()'d */ |
69 | /* cpu_priority_high()'d */ |
63 | struct thread *find_best_thread(void) |
70 | struct thread *find_best_thread(void) |
64 | { |
71 | { |
65 | thread_t *t; |
72 | thread_t *t; |
66 | runq_t *r; |
73 | runq_t *r; |
67 | int i, n; |
74 | int i, n; |
68 | 75 | ||
69 | loop: |
76 | loop: |
70 | cpu_priority_high(); |
77 | cpu_priority_high(); |
71 | 78 | ||
72 | spinlock_lock(&CPU->lock); |
79 | spinlock_lock(&CPU->lock); |
73 | n = CPU->nrdy; |
80 | n = CPU->nrdy; |
74 | spinlock_unlock(&CPU->lock); |
81 | spinlock_unlock(&CPU->lock); |
75 | 82 | ||
76 | cpu_priority_low(); |
83 | cpu_priority_low(); |
77 | 84 | ||
78 | if (n == 0) { |
85 | if (n == 0) { |
79 | #ifdef __SMP__ |
86 | #ifdef __SMP__ |
80 | /* |
87 | /* |
81 | * If the load balancing thread is not running, wake it up and |
88 | * If the load balancing thread is not running, wake it up and |
82 | * set CPU-private flag that the kcpulb has been started. |
89 | * set CPU-private flag that the kcpulb has been started. |
83 | */ |
90 | */ |
84 | if (test_and_set(&CPU->kcpulbstarted) == 0) { |
91 | if (test_and_set(&CPU->kcpulbstarted) == 0) { |
85 | waitq_wakeup(&CPU->kcpulb_wq, 0); |
92 | waitq_wakeup(&CPU->kcpulb_wq, 0); |
86 | goto loop; |
93 | goto loop; |
87 | } |
94 | } |
88 | #endif /* __SMP__ */ |
95 | #endif /* __SMP__ */ |
89 | 96 | ||
90 | /* |
97 | /* |
91 | * For there was nothing to run, the CPU goes to sleep |
98 | * For there was nothing to run, the CPU goes to sleep |
92 | * until a hardware interrupt or an IPI comes. |
99 | * until a hardware interrupt or an IPI comes. |
93 | * This improves energy saving and hyperthreading. |
100 | * This improves energy saving and hyperthreading. |
94 | * On the other hand, several hardware interrupts can be ignored. |
101 | * On the other hand, several hardware interrupts can be ignored. |
95 | */ |
102 | */ |
96 | cpu_sleep(); |
103 | cpu_sleep(); |
97 | goto loop; |
104 | goto loop; |
98 | } |
105 | } |
99 | 106 | ||
100 | cpu_priority_high(); |
107 | cpu_priority_high(); |
101 | 108 | ||
102 | for (i = 0; i<RQ_COUNT; i++) { |
109 | for (i = 0; i<RQ_COUNT; i++) { |
103 | r = &CPU->rq[i]; |
110 | r = &CPU->rq[i]; |
104 | spinlock_lock(&r->lock); |
111 | spinlock_lock(&r->lock); |
105 | if (r->n == 0) { |
112 | if (r->n == 0) { |
106 | /* |
113 | /* |
107 | * If this queue is empty, try a lower-priority queue. |
114 | * If this queue is empty, try a lower-priority queue. |
108 | */ |
115 | */ |
109 | spinlock_unlock(&r->lock); |
116 | spinlock_unlock(&r->lock); |
110 | continue; |
117 | continue; |
111 | } |
118 | } |
112 | 119 | ||
113 | spinlock_lock(&nrdylock); |
120 | spinlock_lock(&nrdylock); |
114 | nrdy--; |
121 | nrdy--; |
115 | spinlock_unlock(&nrdylock); |
122 | spinlock_unlock(&nrdylock); |
116 | 123 | ||
117 | spinlock_lock(&CPU->lock); |
124 | spinlock_lock(&CPU->lock); |
118 | CPU->nrdy--; |
125 | CPU->nrdy--; |
119 | spinlock_unlock(&CPU->lock); |
126 | spinlock_unlock(&CPU->lock); |
120 | 127 | ||
121 | r->n--; |
128 | r->n--; |
122 | 129 | ||
123 | /* |
130 | /* |
124 | * Take the first thread from the queue. |
131 | * Take the first thread from the queue. |
125 | */ |
132 | */ |
126 | t = list_get_instance(r->rq_head.next, thread_t, rq_link); |
133 | t = list_get_instance(r->rq_head.next, thread_t, rq_link); |
127 | list_remove(&t->rq_link); |
134 | list_remove(&t->rq_link); |
128 | 135 | ||
129 | spinlock_unlock(&r->lock); |
136 | spinlock_unlock(&r->lock); |
130 | 137 | ||
131 | spinlock_lock(&t->lock); |
138 | spinlock_lock(&t->lock); |
132 | t->cpu = CPU; |
139 | t->cpu = CPU; |
133 | 140 | ||
134 | t->ticks = us2ticks((i+1)*10000); |
141 | t->ticks = us2ticks((i+1)*10000); |
135 | t->pri = i; /* eventually correct rq index */ |
142 | t->pri = i; /* eventually correct rq index */ |
136 | 143 | ||
137 | /* |
144 | /* |
138 | * Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge. |
145 | * Clear the X_STOLEN flag so that t can be migrated when load balancing needs emerge. |
139 | */ |
146 | */ |
140 | t->flags &= ~X_STOLEN; |
147 | t->flags &= ~X_STOLEN; |
141 | spinlock_unlock(&t->lock); |
148 | spinlock_unlock(&t->lock); |
142 | 149 | ||
143 | return t; |
150 | return t; |
144 | } |
151 | } |
145 | goto loop; |
152 | goto loop; |
146 | 153 | ||
147 | } |
154 | } |
148 | 155 | ||
149 | /* |
156 | /* |
150 | * This function prevents low priority threads from starving in rq's. |
157 | * This function prevents low priority threads from starving in rq's. |
151 | * When it decides to relink rq's, it reconnects respective pointers |
158 | * When it decides to relink rq's, it reconnects respective pointers |
152 | * so that in result threads with 'pri' greater or equal 'start' are |
159 | * so that in result threads with 'pri' greater or equal 'start' are |
153 | * moved to a higher-priority queue. |
160 | * moved to a higher-priority queue. |
154 | */ |
161 | */ |
155 | void relink_rq(int start) |
162 | void relink_rq(int start) |
156 | { |
163 | { |
157 | link_t head; |
164 | link_t head; |
158 | runq_t *r; |
165 | runq_t *r; |
159 | int i, n; |
166 | int i, n; |
160 | 167 | ||
161 | list_initialize(&head); |
168 | list_initialize(&head); |
162 | spinlock_lock(&CPU->lock); |
169 | spinlock_lock(&CPU->lock); |
163 | if (CPU->needs_relink > NEEDS_RELINK_MAX) { |
170 | if (CPU->needs_relink > NEEDS_RELINK_MAX) { |
164 | for (i = start; i<RQ_COUNT-1; i++) { |
171 | for (i = start; i<RQ_COUNT-1; i++) { |
165 | /* remember and empty rq[i + 1] */ |
172 | /* remember and empty rq[i + 1] */ |
166 | r = &CPU->rq[i + 1]; |
173 | r = &CPU->rq[i + 1]; |
167 | spinlock_lock(&r->lock); |
174 | spinlock_lock(&r->lock); |
168 | list_concat(&head, &r->rq_head); |
175 | list_concat(&head, &r->rq_head); |
169 | n = r->n; |
176 | n = r->n; |
170 | r->n = 0; |
177 | r->n = 0; |
171 | spinlock_unlock(&r->lock); |
178 | spinlock_unlock(&r->lock); |
172 | 179 | ||
173 | /* append rq[i + 1] to rq[i] */ |
180 | /* append rq[i + 1] to rq[i] */ |
174 | r = &CPU->rq[i]; |
181 | r = &CPU->rq[i]; |
175 | spinlock_lock(&r->lock); |
182 | spinlock_lock(&r->lock); |
176 | list_concat(&r->rq_head, &head); |
183 | list_concat(&r->rq_head, &head); |
177 | r->n += n; |
184 | r->n += n; |
178 | spinlock_unlock(&r->lock); |
185 | spinlock_unlock(&r->lock); |
179 | } |
186 | } |
180 | CPU->needs_relink = 0; |
187 | CPU->needs_relink = 0; |
181 | } |
188 | } |
182 | spinlock_unlock(&CPU->lock); |
189 | spinlock_unlock(&CPU->lock); |
183 | 190 | ||
184 | } |
191 | } |
185 | 192 | ||
186 | /* |
193 | /* |
187 | * The scheduler. |
194 | * The scheduler. |
188 | */ |
195 | */ |
189 | void scheduler(void) |
196 | void scheduler(void) |
190 | { |
197 | { |
191 | volatile pri_t pri; |
198 | volatile pri_t pri; |
192 | 199 | ||
193 | pri = cpu_priority_high(); |
200 | pri = cpu_priority_high(); |
194 | 201 | ||
195 | if (haltstate) |
202 | if (haltstate) |
196 | halt(); |
203 | halt(); |
197 | 204 | ||
198 | if (THREAD) { |
205 | if (THREAD) { |
199 | spinlock_lock(&THREAD->lock); |
206 | spinlock_lock(&THREAD->lock); |
200 | if (!context_save(&THREAD->saved_context)) { |
207 | if (!context_save(&THREAD->saved_context)) { |
201 | /* |
208 | /* |
202 | * This is the place where threads leave scheduler(); |
209 | * This is the place where threads leave scheduler(); |
203 | */ |
210 | */ |
204 | before_thread_runs(); |
211 | before_thread_runs(); |
205 | spinlock_unlock(&THREAD->lock); |
212 | spinlock_unlock(&THREAD->lock); |
206 | cpu_priority_restore(THREAD->saved_context.pri); |
213 | cpu_priority_restore(THREAD->saved_context.pri); |
207 | return; |
214 | return; |
208 | } |
215 | } |
209 | THREAD->saved_context.pri = pri; |
216 | THREAD->saved_context.pri = pri; |
210 | } |
217 | } |
211 | 218 | ||
212 | /* |
219 | /* |
213 | * We may not keep the old stack. |
220 | * We may not keep the old stack. |
214 | * Reason: If we kept the old stack and got blocked, for instance, in |
221 | * Reason: If we kept the old stack and got blocked, for instance, in |
215 | * find_best_thread(), the old thread could get rescheduled by another |
222 | * find_best_thread(), the old thread could get rescheduled by another |
216 | * CPU and overwrite the part of its own stack that was also used by |
223 | * CPU and overwrite the part of its own stack that was also used by |
217 | * the scheduler on this CPU. |
224 | * the scheduler on this CPU. |
218 | * |
225 | * |
219 | * Moreover, we have to bypass the compiler-generated POP sequence |
226 | * Moreover, we have to bypass the compiler-generated POP sequence |
220 | * which is fooled by SP being set to the very top of the stack. |
227 | * which is fooled by SP being set to the very top of the stack. |
221 | * Therefore the scheduler() function continues in |
228 | * Therefore the scheduler() function continues in |
222 | * scheduler_separated_stack(). |
229 | * scheduler_separated_stack(). |
223 | */ |
230 | */ |
224 | context_save(&CPU->saved_context); |
231 | context_save(&CPU->saved_context); |
225 | CPU->saved_context.sp = (__address) &CPU->stack[CPU_STACK_SIZE-8]; |
232 | CPU->saved_context.sp = (__address) &CPU->stack[CPU_STACK_SIZE-8]; |
226 | CPU->saved_context.pc = (__address) scheduler_separated_stack; |
233 | CPU->saved_context.pc = (__address) scheduler_separated_stack; |
227 | context_restore(&CPU->saved_context); |
234 | context_restore(&CPU->saved_context); |
228 | /* not reached */ |
235 | /* not reached */ |
229 | } |
236 | } |
230 | 237 | ||
231 | void scheduler_separated_stack(void) |
238 | void scheduler_separated_stack(void) |
232 | { |
239 | { |
233 | int priority; |
240 | int priority; |
234 | 241 | ||
235 | if (THREAD) { |
242 | if (THREAD) { |
236 | switch (THREAD->state) { |
243 | switch (THREAD->state) { |
237 | case Running: |
244 | case Running: |
238 | THREAD->state = Ready; |
245 | THREAD->state = Ready; |
239 | spinlock_unlock(&THREAD->lock); |
246 | spinlock_unlock(&THREAD->lock); |
240 | thread_ready(THREAD); |
247 | thread_ready(THREAD); |
241 | break; |
248 | break; |
242 | 249 | ||
243 | case Exiting: |
250 | case Exiting: |
244 | frame_free((__address) THREAD->kstack); |
251 | frame_free((__address) THREAD->kstack); |
245 | if (THREAD->ustack) { |
252 | if (THREAD->ustack) { |
246 | frame_free((__address) THREAD->ustack); |
253 | frame_free((__address) THREAD->ustack); |
247 | } |
254 | } |
248 | 255 | ||
249 | /* |
256 | /* |
250 | * Detach from the containing task. |
257 | * Detach from the containing task. |
251 | */ |
258 | */ |
252 | spinlock_lock(&TASK->lock); |
259 | spinlock_lock(&TASK->lock); |
253 | list_remove(&THREAD->th_link); |
260 | list_remove(&THREAD->th_link); |
254 | spinlock_unlock(&TASK->lock); |
261 | spinlock_unlock(&TASK->lock); |
255 | 262 | ||
256 | spinlock_unlock(&THREAD->lock); |
263 | spinlock_unlock(&THREAD->lock); |
257 | 264 | ||
258 | spinlock_lock(&threads_lock); |
265 | spinlock_lock(&threads_lock); |
259 | list_remove(&THREAD->threads_link); |
266 | list_remove(&THREAD->threads_link); |
260 | spinlock_unlock(&threads_lock); |
267 | spinlock_unlock(&threads_lock); |
261 | 268 | ||
262 | free(THREAD); |
269 | free(THREAD); |
263 | 270 | ||
264 | break; |
271 | break; |
265 | 272 | ||
266 | case Sleeping: |
273 | case Sleeping: |
267 | /* |
274 | /* |
268 | * Prefer the thread after it's woken up. |
275 | * Prefer the thread after it's woken up. |
269 | */ |
276 | */ |
270 | THREAD->pri = -1; |
277 | THREAD->pri = -1; |
271 | 278 | ||
272 | /* |
279 | /* |
273 | * We need to release wq->lock which we locked in waitq_sleep(). |
280 | * We need to release wq->lock which we locked in waitq_sleep(). |
274 | * Address of wq->lock is kept in THREAD->sleep_queue. |
281 | * Address of wq->lock is kept in THREAD->sleep_queue. |
275 | */ |
282 | */ |
276 | spinlock_unlock(&THREAD->sleep_queue->lock); |
283 | spinlock_unlock(&THREAD->sleep_queue->lock); |
277 | 284 | ||
278 | /* |
285 | /* |
279 | * Check for possible requests for out-of-context invocation. |
286 | * Check for possible requests for out-of-context invocation. |
280 | */ |
287 | */ |
281 | if (THREAD->call_me) { |
288 | if (THREAD->call_me) { |
282 | THREAD->call_me(THREAD->call_me_with); |
289 | THREAD->call_me(THREAD->call_me_with); |
283 | THREAD->call_me = NULL; |
290 | THREAD->call_me = NULL; |
284 | THREAD->call_me_with = NULL; |
291 | THREAD->call_me_with = NULL; |
285 | } |
292 | } |
286 | 293 | ||
287 | spinlock_unlock(&THREAD->lock); |
294 | spinlock_unlock(&THREAD->lock); |
288 | 295 | ||
289 | break; |
296 | break; |
290 | 297 | ||
291 | default: |
298 | default: |
292 | /* |
299 | /* |
293 | * Entering state is unexpected. |
300 | * Entering state is unexpected. |
294 | */ |
301 | */ |
295 | panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]); |
302 | panic("tid%d: unexpected state %s\n", THREAD->tid, thread_states[THREAD->state]); |
296 | break; |
303 | break; |
297 | } |
304 | } |
298 | THREAD = NULL; |
305 | THREAD = NULL; |
299 | } |
306 | } |
300 | 307 | ||
301 | THREAD = find_best_thread(); |
308 | THREAD = find_best_thread(); |
302 | 309 | ||
303 | spinlock_lock(&THREAD->lock); |
310 | spinlock_lock(&THREAD->lock); |
304 | priority = THREAD->pri; |
311 | priority = THREAD->pri; |
305 | spinlock_unlock(&THREAD->lock); |
312 | spinlock_unlock(&THREAD->lock); |
306 | 313 | ||
307 | relink_rq(priority); |
314 | relink_rq(priority); |
308 | 315 | ||
309 | spinlock_lock(&THREAD->lock); |
316 | spinlock_lock(&THREAD->lock); |
310 | 317 | ||
311 | /* |
318 | /* |
312 | * If both the old and the new task are the same, lots of work is avoided. |
319 | * If both the old and the new task are the same, lots of work is avoided. |
313 | */ |
320 | */ |
314 | if (TASK != THREAD->task) { |
321 | if (TASK != THREAD->task) { |
315 | vm_t *m1 = NULL; |
322 | vm_t *m1 = NULL; |
316 | vm_t *m2; |
323 | vm_t *m2; |
317 | 324 | ||
318 | if (TASK) { |
325 | if (TASK) { |
319 | spinlock_lock(&TASK->lock); |
326 | spinlock_lock(&TASK->lock); |
320 | m1 = TASK->vm; |
327 | m1 = TASK->vm; |
321 | spinlock_unlock(&TASK->lock); |
328 | spinlock_unlock(&TASK->lock); |
322 | } |
329 | } |
323 | 330 | ||
324 | spinlock_lock(&THREAD->task->lock); |
331 | spinlock_lock(&THREAD->task->lock); |
325 | m2 = THREAD->task->vm; |
332 | m2 = THREAD->task->vm; |
326 | spinlock_unlock(&THREAD->task->lock); |
333 | spinlock_unlock(&THREAD->task->lock); |
327 | 334 | ||
328 | /* |
335 | /* |
329 | * Note that it is possible for two tasks to share one vm mapping. |
336 | * Note that it is possible for two tasks to share one vm mapping. |
330 | */ |
337 | */ |
331 | if (m1 != m2) { |
338 | if (m1 != m2) { |
332 | /* |
339 | /* |
333 | * Both tasks and vm mappings are different. |
340 | * Both tasks and vm mappings are different. |
334 | * Replace the old one with the new one. |
341 | * Replace the old one with the new one. |
335 | */ |
342 | */ |
336 | if (m1) { |
343 | if (m1) { |
337 | vm_uninstall(m1); |
344 | vm_uninstall(m1); |
338 | } |
345 | } |
339 | vm_install(m2); |
346 | vm_install(m2); |
340 | } |
347 | } |
341 | TASK = THREAD->task; |
348 | TASK = THREAD->task; |
342 | } |
349 | } |
343 | 350 | ||
344 | THREAD->state = Running; |
351 | THREAD->state = Running; |
345 | 352 | ||
346 | #ifdef SCHEDULER_VERBOSE |
353 | #ifdef SCHEDULER_VERBOSE |
347 | printf("cpu%d: tid %d (pri=%d,ticks=%d,nrdy=%d)\n", CPU->id, THREAD->tid, THREAD->pri, THREAD->ticks, CPU->nrdy); |
354 | printf("cpu%d: tid %d (pri=%d,ticks=%d,nrdy=%d)\n", CPU->id, THREAD->tid, THREAD->pri, THREAD->ticks, CPU->nrdy); |
348 | #endif |
355 | #endif |
349 | 356 | ||
350 | context_restore(&THREAD->saved_context); |
357 | context_restore(&THREAD->saved_context); |
351 | /* not reached */ |
358 | /* not reached */ |
352 | } |
359 | } |
353 | 360 | ||
354 | #ifdef __SMP__ |
361 | #ifdef __SMP__ |
355 | /* |
362 | /* |
356 | * This is the load balancing thread. |
363 | * This is the load balancing thread. |
357 | * It supervises thread supplies for the CPU it's wired to. |
364 | * It supervises thread supplies for the CPU it's wired to. |
358 | */ |
365 | */ |
359 | void kcpulb(void *arg) |
366 | void kcpulb(void *arg) |
360 | { |
367 | { |
361 | thread_t *t; |
368 | thread_t *t; |
362 | int count, i, j, k = 0; |
369 | int count, i, j, k = 0; |
363 | pri_t pri; |
370 | pri_t pri; |
364 | 371 | ||
365 | loop: |
372 | loop: |
366 | /* |
373 | /* |
367 | * Sleep until there's some work to do. |
374 | * Sleep until there's some work to do. |
368 | */ |
375 | */ |
369 | waitq_sleep(&CPU->kcpulb_wq); |
376 | waitq_sleep(&CPU->kcpulb_wq); |
370 | 377 | ||
371 | not_satisfied: |
378 | not_satisfied: |
372 | /* |
379 | /* |
373 | * Calculate the number of threads that will be migrated/stolen from |
380 | * Calculate the number of threads that will be migrated/stolen from |
374 | * other CPU's. Note that situation can have changed between two |
381 | * other CPU's. Note that situation can have changed between two |
375 | * passes. Each time get the most up to date counts. |
382 | * passes. Each time get the most up to date counts. |
376 | */ |
383 | */ |
377 | pri = cpu_priority_high(); |
384 | pri = cpu_priority_high(); |
378 | spinlock_lock(&CPU->lock); |
385 | spinlock_lock(&CPU->lock); |
379 | count = nrdy / config.cpu_active; |
386 | count = nrdy / config.cpu_active; |
380 | count -= CPU->nrdy; |
387 | count -= CPU->nrdy; |
381 | spinlock_unlock(&CPU->lock); |
388 | spinlock_unlock(&CPU->lock); |
382 | cpu_priority_restore(pri); |
389 | cpu_priority_restore(pri); |
383 | 390 | ||
384 | if (count <= 0) |
391 | if (count <= 0) |
385 | goto satisfied; |
392 | goto satisfied; |
386 | 393 | ||
387 | /* |
394 | /* |
388 | * Searching least priority queues on all CPU's first and most priority queues on all CPU's last. |
395 | * Searching least priority queues on all CPU's first and most priority queues on all CPU's last. |
389 | */ |
396 | */ |
390 | for (j=RQ_COUNT-1; j >= 0; j--) { |
397 | for (j=RQ_COUNT-1; j >= 0; j--) { |
391 | for (i=0; i < config.cpu_active; i++) { |
398 | for (i=0; i < config.cpu_active; i++) { |
392 | link_t *l; |
399 | link_t *l; |
393 | runq_t *r; |
400 | runq_t *r; |
394 | cpu_t *cpu; |
401 | cpu_t *cpu; |
395 | 402 | ||
396 | cpu = &cpus[(i + k) % config.cpu_active]; |
403 | cpu = &cpus[(i + k) % config.cpu_active]; |
397 | r = &cpu->rq[j]; |
404 | r = &cpu->rq[j]; |
398 | 405 | ||
399 | /* |
406 | /* |
400 | * Not interested in ourselves. |
407 | * Not interested in ourselves. |
401 | * Doesn't require interrupt disabling for kcpulb is X_WIRED. |
408 | * Doesn't require interrupt disabling for kcpulb is X_WIRED. |
402 | */ |
409 | */ |
403 | if (CPU == cpu) |
410 | if (CPU == cpu) |
404 | continue; |
411 | continue; |
405 | 412 | ||
406 | restart: pri = cpu_priority_high(); |
413 | restart: pri = cpu_priority_high(); |
407 | spinlock_lock(&r->lock); |
414 | spinlock_lock(&r->lock); |
408 | if (r->n == 0) { |
415 | if (r->n == 0) { |
409 | spinlock_unlock(&r->lock); |
416 | spinlock_unlock(&r->lock); |
410 | cpu_priority_restore(pri); |
417 | cpu_priority_restore(pri); |
411 | continue; |
418 | continue; |
412 | } |
419 | } |
413 | 420 | ||
414 | t = NULL; |
421 | t = NULL; |
415 | l = r->rq_head.prev; /* search rq from the back */ |
422 | l = r->rq_head.prev; /* search rq from the back */ |
416 | while (l != &r->rq_head) { |
423 | while (l != &r->rq_head) { |
417 | t = list_get_instance(l, thread_t, rq_link); |
424 | t = list_get_instance(l, thread_t, rq_link); |
418 | /* |
425 | /* |
419 | * We don't want to steal CPU-wired threads neither threads already stolen. |
426 | * We don't want to steal CPU-wired threads neither threads already stolen. |
420 | * The latter prevents threads from migrating between CPU's without ever being run. |
427 | * The latter prevents threads from migrating between CPU's without ever being run. |
421 | */ |
428 | */ |
422 | spinlock_lock(&t->lock); |
429 | spinlock_lock(&t->lock); |
423 | if (!(t->flags & (X_WIRED | X_STOLEN))) { |
430 | if (!(t->flags & (X_WIRED | X_STOLEN))) { |
424 | /* |
431 | /* |
425 | * Remove t from r. |
432 | * Remove t from r. |
426 | */ |
433 | */ |
427 | 434 | ||
428 | spinlock_unlock(&t->lock); |
435 | spinlock_unlock(&t->lock); |
429 | 436 | ||
430 | /* |
437 | /* |
431 | * Here we have to avoid deadlock with relink_rq(), |
438 | * Here we have to avoid deadlock with relink_rq(), |
432 | * because it locks cpu and r in a different order than we do. |
439 | * because it locks cpu and r in a different order than we do. |
433 | */ |
440 | */ |
434 | if (!spinlock_trylock(&cpu->lock)) { |
441 | if (!spinlock_trylock(&cpu->lock)) { |
435 | /* Release all locks and try again. */ |
442 | /* Release all locks and try again. */ |
436 | spinlock_unlock(&r->lock); |
443 | spinlock_unlock(&r->lock); |
437 | cpu_priority_restore(pri); |
444 | cpu_priority_restore(pri); |
438 | goto restart; |
445 | goto restart; |
439 | } |
446 | } |
440 | cpu->nrdy--; |
447 | cpu->nrdy--; |
441 | spinlock_unlock(&cpu->lock); |
448 | spinlock_unlock(&cpu->lock); |
442 | 449 | ||
443 | spinlock_lock(&nrdylock); |
450 | spinlock_lock(&nrdylock); |
444 | nrdy--; |
451 | nrdy--; |
445 | spinlock_unlock(&nrdylock); |
452 | spinlock_unlock(&nrdylock); |
446 | 453 | ||
447 | r->n--; |
454 | r->n--; |
448 | list_remove(&t->rq_link); |
455 | list_remove(&t->rq_link); |
449 | 456 | ||
450 | break; |
457 | break; |
451 | } |
458 | } |
452 | spinlock_unlock(&t->lock); |
459 | spinlock_unlock(&t->lock); |
453 | l = l->prev; |
460 | l = l->prev; |
454 | t = NULL; |
461 | t = NULL; |
455 | } |
462 | } |
456 | spinlock_unlock(&r->lock); |
463 | spinlock_unlock(&r->lock); |
457 | 464 | ||
458 | if (t) { |
465 | if (t) { |
459 | /* |
466 | /* |
460 | * Ready t on local CPU |
467 | * Ready t on local CPU |
461 | */ |
468 | */ |
462 | spinlock_lock(&t->lock); |
469 | spinlock_lock(&t->lock); |
463 | #ifdef KCPULB_VERBOSE |
470 | #ifdef KCPULB_VERBOSE |
464 | printf("kcpulb%d: TID %d -> cpu%d, nrdy=%d, avg=%d\n", CPU->id, t->tid, CPU->id, CPU->nrdy, nrdy / config.cpu_active); |
471 | printf("kcpulb%d: TID %d -> cpu%d, nrdy=%d, avg=%d\n", CPU->id, t->tid, CPU->id, CPU->nrdy, nrdy / config.cpu_active); |
465 | #endif |
472 | #endif |
466 | t->flags |= X_STOLEN; |
473 | t->flags |= X_STOLEN; |
467 | spinlock_unlock(&t->lock); |
474 | spinlock_unlock(&t->lock); |
468 | 475 | ||
469 | thread_ready(t); |
476 | thread_ready(t); |
470 | 477 | ||
471 | cpu_priority_restore(pri); |
478 | cpu_priority_restore(pri); |
472 | 479 | ||
473 | if (--count == 0) |
480 | if (--count == 0) |
474 | goto satisfied; |
481 | goto satisfied; |
475 | 482 | ||
476 | /* |
483 | /* |
477 | * We are not satisfied yet, focus on another CPU next time. |
484 | * We are not satisfied yet, focus on another CPU next time. |
478 | */ |
485 | */ |
479 | k++; |
486 | k++; |
480 | 487 | ||
481 | continue; |
488 | continue; |
482 | } |
489 | } |
483 | cpu_priority_restore(pri); |
490 | cpu_priority_restore(pri); |
484 | } |
491 | } |
485 | } |
492 | } |
486 | 493 | ||
487 | if (CPU->nrdy) { |
494 | if (CPU->nrdy) { |
488 | /* |
495 | /* |
489 | * Be a little bit light-weight and let migrated threads run. |
496 | * Be a little bit light-weight and let migrated threads run. |
490 | */ |
497 | */ |
491 | scheduler(); |
498 | scheduler(); |
492 | } |
499 | } |
493 | else { |
500 | else { |
494 | /* |
501 | /* |
495 | * We failed to migrate a single thread. |
502 | * We failed to migrate a single thread. |
496 | * Something more sophisticated should be done. |
503 | * Something more sophisticated should be done. |
497 | */ |
504 | */ |
498 | scheduler(); |
505 | scheduler(); |
499 | } |
506 | } |
500 | 507 | ||
501 | goto not_satisfied; |
508 | goto not_satisfied; |
502 | 509 | ||
503 | satisfied: |
510 | satisfied: |
504 | /* |
511 | /* |
505 | * Tell find_best_thread() to wake us up later again. |
512 | * Tell find_best_thread() to wake us up later again. |
506 | */ |
513 | */ |
507 | CPU->kcpulbstarted = 0; |
514 | CPU->kcpulbstarted = 0; |
508 | goto loop; |
515 | goto loop; |
509 | } |
516 | } |
510 | 517 | ||
511 | #endif /* __SMP__ */ |
518 | #endif /* __SMP__ */ |
512 | 519 |