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