1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* sched.c - SPU scheduler.
3 *
4 * Copyright (C) IBM 2005
5 * Author: Mark Nutter <mnutter@us.ibm.com>
6 *
7 * 2006-03-31 NUMA domains added.
8 */
9
10 #undef DEBUG
11
12 #include <linux/errno.h>
13 #include <linux/sched/signal.h>
14 #include <linux/sched/loadavg.h>
15 #include <linux/sched/rt.h>
16 #include <linux/kernel.h>
17 #include <linux/mm.h>
18 #include <linux/slab.h>
19 #include <linux/completion.h>
20 #include <linux/vmalloc.h>
21 #include <linux/smp.h>
22 #include <linux/stddef.h>
23 #include <linux/unistd.h>
24 #include <linux/numa.h>
25 #include <linux/mutex.h>
26 #include <linux/notifier.h>
27 #include <linux/kthread.h>
28 #include <linux/pid_namespace.h>
29 #include <linux/proc_fs.h>
30 #include <linux/seq_file.h>
31
32 #include <asm/io.h>
33 #include <asm/mmu_context.h>
34 #include <asm/spu.h>
35 #include <asm/spu_csa.h>
36 #include <asm/spu_priv1.h>
37 #include "spufs.h"
38 #define CREATE_TRACE_POINTS
39 #include "sputrace.h"
40
41 struct spu_prio_array {
42 DECLARE_BITMAP(bitmap, MAX_PRIO);
43 struct list_head runq[MAX_PRIO];
44 spinlock_t runq_lock;
45 int nr_waiting;
46 };
47
48 static unsigned long spu_avenrun[3];
49 static struct spu_prio_array *spu_prio;
50 static struct task_struct *spusched_task;
51 static struct timer_list spusched_timer;
52 static struct timer_list spuloadavg_timer;
53
54 /*
55 * Priority of a normal, non-rt, non-niced'd process (aka nice level 0).
56 */
57 #define NORMAL_PRIO 120
58
59 /*
60 * Frequency of the spu scheduler tick. By default we do one SPU scheduler
61 * tick for every 10 CPU scheduler ticks.
62 */
63 #define SPUSCHED_TICK (10)
64
65 /*
66 * These are the 'tuning knobs' of the scheduler:
67 *
68 * Minimum timeslice is 5 msecs (or 1 spu scheduler tick, whichever is
69 * larger), default timeslice is 100 msecs, maximum timeslice is 800 msecs.
70 */
71 #define MIN_SPU_TIMESLICE max(5 * HZ / (1000 * SPUSCHED_TICK), 1)
72 #define DEF_SPU_TIMESLICE (100 * HZ / (1000 * SPUSCHED_TICK))
73
74 #define SCALE_PRIO(x, prio) \
75 max(x * (MAX_PRIO - prio) / (NICE_WIDTH / 2), MIN_SPU_TIMESLICE)
76
77 /*
78 * scale user-nice values [ -20 ... 0 ... 19 ] to time slice values:
79 * [800ms ... 100ms ... 5ms]
80 *
81 * The higher a thread's priority, the bigger timeslices
82 * it gets during one round of execution. But even the lowest
83 * priority thread gets MIN_TIMESLICE worth of execution time.
84 */
85 void spu_set_timeslice(struct spu_context *ctx)
86 {
87 if (ctx->prio < NORMAL_PRIO)
88 ctx->time_slice = SCALE_PRIO(DEF_SPU_TIMESLICE * 4, ctx->prio);
89 else
90 ctx->time_slice = SCALE_PRIO(DEF_SPU_TIMESLICE, ctx->prio);
91 }
92
93 /*
94 * Update scheduling information from the owning thread.
95 */
96 void __spu_update_sched_info(struct spu_context *ctx)
97 {
98 /*
99 * assert that the context is not on the runqueue, so it is safe
100 * to change its scheduling parameters.
101 */
102 BUG_ON(!list_empty(&ctx->rq));
103
104 /*
105 * 32-Bit assignments are atomic on powerpc, and we don't care about
106 * memory ordering here because retrieving the controlling thread is
107 * per definition racy.
108 */
109 ctx->tid = current->pid;
110
111 /*
112 * We do our own priority calculations, so we normally want
113 * ->static_prio to start with. Unfortunately this field
114 * contains junk for threads with a realtime scheduling
115 * policy so we have to look at ->prio in this case.
116 */
117 if (rt_prio(current->prio))
118 ctx->prio = current->prio;
119 else
120 ctx->prio = current->static_prio;
121 ctx->policy = current->policy;
122
123 /*
124 * TO DO: the context may be loaded, so we may need to activate
125 * it again on a different node. But it shouldn't hurt anything
126 * to update its parameters, because we know that the scheduler
127 * is not actively looking at this field, since it is not on the
128 * runqueue. The context will be rescheduled on the proper node
129 * if it is timesliced or preempted.
130 */
131 cpumask_copy(&ctx->cpus_allowed, current->cpus_ptr);
132
133 /* Save the current cpu id for spu interrupt routing. */
134 ctx->last_ran = raw_smp_processor_id();
135 }
136
137 void spu_update_sched_info(struct spu_context *ctx)
138 {
139 int node;
140
141 if (ctx->state == SPU_STATE_RUNNABLE) {
142 node = ctx->spu->node;
143
144 /*
145 * Take list_mutex to sync with find_victim().
146 */
147 mutex_lock(&cbe_spu_info[node].list_mutex);
148 __spu_update_sched_info(ctx);
149 mutex_unlock(&cbe_spu_info[node].list_mutex);
150 } else {
151 __spu_update_sched_info(ctx);
152 }
153 }
154
155 static int __node_allowed(struct spu_context *ctx, int node)
156 {
157 if (nr_cpus_node(node)) {
158 const struct cpumask *mask = cpumask_of_node(node);
159
160 if (cpumask_intersects(mask, &ctx->cpus_allowed))
161 return 1;
162 }
163
164 return 0;
165 }
166
167 static int node_allowed(struct spu_context *ctx, int node)
168 {
169 int rval;
170
171 spin_lock(&spu_prio->runq_lock);
172 rval = __node_allowed(ctx, node);
173 spin_unlock(&spu_prio->runq_lock);
174
175 return rval;
176 }
177
178 void do_notify_spus_active(void)
179 {
180 int node;
181
182 /*
183 * Wake up the active spu_contexts.
184 */
185 for_each_online_node(node) {
186 struct spu *spu;
187
188 mutex_lock(&cbe_spu_info[node].list_mutex);
189 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
190 if (spu->alloc_state != SPU_FREE) {
191 struct spu_context *ctx = spu->ctx;
192 set_bit(SPU_SCHED_NOTIFY_ACTIVE,
193 &ctx->sched_flags);
194 mb();
195 wake_up_all(&ctx->stop_wq);
196 }
197 }
198 mutex_unlock(&cbe_spu_info[node].list_mutex);
199 }
200 }
201
202 /**
203 * spu_bind_context - bind spu context to physical spu
204 * @spu: physical spu to bind to
205 * @ctx: context to bind
206 */
207 static void spu_bind_context(struct spu *spu, struct spu_context *ctx)
208 {
209 spu_context_trace(spu_bind_context__enter, ctx, spu);
210
211 spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
212
213 if (ctx->flags & SPU_CREATE_NOSCHED)
214 atomic_inc(&cbe_spu_info[spu->node].reserved_spus);
215
216 ctx->stats.slb_flt_base = spu->stats.slb_flt;
217 ctx->stats.class2_intr_base = spu->stats.class2_intr;
218
219 spu_associate_mm(spu, ctx->owner);
220
221 spin_lock_irq(&spu->register_lock);
222 spu->ctx = ctx;
223 spu->flags = 0;
224 ctx->spu = spu;
225 ctx->ops = &spu_hw_ops;
226 spu->pid = current->pid;
227 spu->tgid = current->tgid;
228 spu->ibox_callback = spufs_ibox_callback;
229 spu->wbox_callback = spufs_wbox_callback;
230 spu->stop_callback = spufs_stop_callback;
231 spu->mfc_callback = spufs_mfc_callback;
232 spin_unlock_irq(&spu->register_lock);
233
234 spu_unmap_mappings(ctx);
235
236 spu_switch_log_notify(spu, ctx, SWITCH_LOG_START, 0);
237 spu_restore(&ctx->csa, spu);
238 spu->timestamp = jiffies;
239 ctx->state = SPU_STATE_RUNNABLE;
240
241 spuctx_switch_state(ctx, SPU_UTIL_USER);
242 }
243
244 /*
245 * Must be used with the list_mutex held.
246 */
247 static inline int sched_spu(struct spu *spu)
248 {
249 BUG_ON(!mutex_is_locked(&cbe_spu_info[spu->node].list_mutex));
250
251 return (!spu->ctx || !(spu->ctx->flags & SPU_CREATE_NOSCHED));
252 }
253
254 static void aff_merge_remaining_ctxs(struct spu_gang *gang)
255 {
256 struct spu_context *ctx;
257
258 list_for_each_entry(ctx, &gang->aff_list_head, aff_list) {
259 if (list_empty(&ctx->aff_list))
260 list_add(&ctx->aff_list, &gang->aff_list_head);
261 }
262 gang->aff_flags |= AFF_MERGED;
263 }
264
265 static void aff_set_offsets(struct spu_gang *gang)
266 {
267 struct spu_context *ctx;
268 int offset;
269
270 offset = -1;
271 list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list,
272 aff_list) {
273 if (&ctx->aff_list == &gang->aff_list_head)
274 break;
275 ctx->aff_offset = offset--;
276 }
277
278 offset = 0;
279 list_for_each_entry(ctx, gang->aff_ref_ctx->aff_list.prev, aff_list) {
280 if (&ctx->aff_list == &gang->aff_list_head)
281 break;
282 ctx->aff_offset = offset++;
283 }
284
285 gang->aff_flags |= AFF_OFFSETS_SET;
286 }
287
288 static struct spu *aff_ref_location(struct spu_context *ctx, int mem_aff,
289 int group_size, int lowest_offset)
290 {
291 struct spu *spu;
292 int node, n;
293
294 /*
295 * TODO: A better algorithm could be used to find a good spu to be
296 * used as reference location for the ctxs chain.
297 */
298 node = cpu_to_node(raw_smp_processor_id());
299 for (n = 0; n < MAX_NUMNODES; n++, node++) {
300 /*
301 * "available_spus" counts how many spus are not potentially
302 * going to be used by other affinity gangs whose reference
303 * context is already in place. Although this code seeks to
304 * avoid having affinity gangs with a summed amount of
305 * contexts bigger than the amount of spus in the node,
306 * this may happen sporadically. In this case, available_spus
307 * becomes negative, which is harmless.
308 */
309 int available_spus;
310
311 node = (node < MAX_NUMNODES) ? node : 0;
312 if (!node_allowed(ctx, node))
313 continue;
314
315 available_spus = 0;
316 mutex_lock(&cbe_spu_info[node].list_mutex);
317 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
318 if (spu->ctx && spu->ctx->gang && !spu->ctx->aff_offset
319 && spu->ctx->gang->aff_ref_spu)
320 available_spus -= spu->ctx->gang->contexts;
321 available_spus++;
322 }
323 if (available_spus < ctx->gang->contexts) {
324 mutex_unlock(&cbe_spu_info[node].list_mutex);
325 continue;
326 }
327
328 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
329 if ((!mem_aff || spu->has_mem_affinity) &&
330 sched_spu(spu)) {
331 mutex_unlock(&cbe_spu_info[node].list_mutex);
332 return spu;
333 }
334 }
335 mutex_unlock(&cbe_spu_info[node].list_mutex);
336 }
337 return NULL;
338 }
339
340 static void aff_set_ref_point_location(struct spu_gang *gang)
341 {
342 int mem_aff, gs, lowest_offset;
343 struct spu_context *tmp, *ctx;
344
345 mem_aff = gang->aff_ref_ctx->flags & SPU_CREATE_AFFINITY_MEM;
346 lowest_offset = 0;
347 gs = 0;
348
349 list_for_each_entry(tmp, &gang->aff_list_head, aff_list)
350 gs++;
351
352 list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list,
353 aff_list) {
354 if (&ctx->aff_list == &gang->aff_list_head)
355 break;
356 lowest_offset = ctx->aff_offset;
357 }
358
359 gang->aff_ref_spu = aff_ref_location(gang->aff_ref_ctx, mem_aff, gs,
360 lowest_offset);
361 }
362
363 static struct spu *ctx_location(struct spu *ref, int offset, int node)
364 {
365 struct spu *spu;
366
367 spu = NULL;
368 if (offset >= 0) {
369 list_for_each_entry(spu, ref->aff_list.prev, aff_list) {
370 BUG_ON(spu->node != node);
371 if (offset == 0)
372 break;
373 if (sched_spu(spu))
374 offset--;
375 }
376 } else {
377 list_for_each_entry_reverse(spu, ref->aff_list.next, aff_list) {
378 BUG_ON(spu->node != node);
379 if (offset == 0)
380 break;
381 if (sched_spu(spu))
382 offset++;
383 }
384 }
385
386 return spu;
387 }
388
389 /*
390 * affinity_check is called each time a context is going to be scheduled.
391 * It returns the spu ptr on which the context must run.
392 */
393 static int has_affinity(struct spu_context *ctx)
394 {
395 struct spu_gang *gang = ctx->gang;
396
397 if (list_empty(&ctx->aff_list))
398 return 0;
399
400 if (atomic_read(&ctx->gang->aff_sched_count) == 0)
401 ctx->gang->aff_ref_spu = NULL;
402
403 if (!gang->aff_ref_spu) {
404 if (!(gang->aff_flags & AFF_MERGED))
405 aff_merge_remaining_ctxs(gang);
406 if (!(gang->aff_flags & AFF_OFFSETS_SET))
407 aff_set_offsets(gang);
408 aff_set_ref_point_location(gang);
409 }
410
411 return gang->aff_ref_spu != NULL;
412 }
413
414 /**
415 * spu_unbind_context - unbind spu context from physical spu
416 * @spu: physical spu to unbind from
417 * @ctx: context to unbind
418 */
419 static void spu_unbind_context(struct spu *spu, struct spu_context *ctx)
420 {
421 u32 status;
422
423 spu_context_trace(spu_unbind_context__enter, ctx, spu);
424
425 spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
426
427 if (spu->ctx->flags & SPU_CREATE_NOSCHED)
428 atomic_dec(&cbe_spu_info[spu->node].reserved_spus);
429
430 if (ctx->gang)
431 /*
432 * If ctx->gang->aff_sched_count is positive, SPU affinity is
433 * being considered in this gang. Using atomic_dec_if_positive
434 * allow us to skip an explicit check for affinity in this gang
435 */
436 atomic_dec_if_positive(&ctx->gang->aff_sched_count);
437
438 spu_unmap_mappings(ctx);
439 spu_save(&ctx->csa, spu);
440 spu_switch_log_notify(spu, ctx, SWITCH_LOG_STOP, 0);
441
442 spin_lock_irq(&spu->register_lock);
443 spu->timestamp = jiffies;
444 ctx->state = SPU_STATE_SAVED;
445 spu->ibox_callback = NULL;
446 spu->wbox_callback = NULL;
447 spu->stop_callback = NULL;
448 spu->mfc_callback = NULL;
449 spu->pid = 0;
450 spu->tgid = 0;
451 ctx->ops = &spu_backing_ops;
452 spu->flags = 0;
453 spu->ctx = NULL;
454 spin_unlock_irq(&spu->register_lock);
455
456 spu_associate_mm(spu, NULL);
457
458 ctx->stats.slb_flt +=
459 (spu->stats.slb_flt - ctx->stats.slb_flt_base);
460 ctx->stats.class2_intr +=
461 (spu->stats.class2_intr - ctx->stats.class2_intr_base);
462
463 /* This maps the underlying spu state to idle */
464 spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
465 ctx->spu = NULL;
466
467 if (spu_stopped(ctx, &status))
468 wake_up_all(&ctx->stop_wq);
469 }
470
471 /**
472 * spu_add_to_rq - add a context to the runqueue
473 * @ctx: context to add
474 */
475 static void __spu_add_to_rq(struct spu_context *ctx)
476 {
477 /*
478 * Unfortunately this code path can be called from multiple threads
479 * on behalf of a single context due to the way the problem state
480 * mmap support works.
481 *
482 * Fortunately we need to wake up all these threads at the same time
483 * and can simply skip the runqueue addition for every but the first
484 * thread getting into this codepath.
485 *
486 * It's still quite hacky, and long-term we should proxy all other
487 * threads through the owner thread so that spu_run is in control
488 * of all the scheduling activity for a given context.
489 */
490 if (list_empty(&ctx->rq)) {
491 list_add_tail(&ctx->rq, &spu_prio->runq[ctx->prio]);
492 set_bit(ctx->prio, spu_prio->bitmap);
493 if (!spu_prio->nr_waiting++)
494 mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
495 }
496 }
497
498 static void spu_add_to_rq(struct spu_context *ctx)
499 {
500 spin_lock(&spu_prio->runq_lock);
501 __spu_add_to_rq(ctx);
502 spin_unlock(&spu_prio->runq_lock);
503 }
504
505 static void __spu_del_from_rq(struct spu_context *ctx)
506 {
507 int prio = ctx->prio;
508
509 if (!list_empty(&ctx->rq)) {
510 if (!--spu_prio->nr_waiting)
511 del_timer(&spusched_timer);
512 list_del_init(&ctx->rq);
513
514 if (list_empty(&spu_prio->runq[prio]))
515 clear_bit(prio, spu_prio->bitmap);
516 }
517 }
518
519 void spu_del_from_rq(struct spu_context *ctx)
520 {
521 spin_lock(&spu_prio->runq_lock);
522 __spu_del_from_rq(ctx);
523 spin_unlock(&spu_prio->runq_lock);
524 }
525
526 static void spu_prio_wait(struct spu_context *ctx)
527 {
528 DEFINE_WAIT(wait);
529
530 /*
531 * The caller must explicitly wait for a context to be loaded
532 * if the nosched flag is set. If NOSCHED is not set, the caller
533 * queues the context and waits for an spu event or error.
534 */
535 BUG_ON(!(ctx->flags & SPU_CREATE_NOSCHED));
536
537 spin_lock(&spu_prio->runq_lock);
538 prepare_to_wait_exclusive(&ctx->stop_wq, &wait, TASK_INTERRUPTIBLE);
539 if (!signal_pending(current)) {
540 __spu_add_to_rq(ctx);
541 spin_unlock(&spu_prio->runq_lock);
542 mutex_unlock(&ctx->state_mutex);
543 schedule();
544 mutex_lock(&ctx->state_mutex);
545 spin_lock(&spu_prio->runq_lock);
546 __spu_del_from_rq(ctx);
547 }
548 spin_unlock(&spu_prio->runq_lock);
549 __set_current_state(TASK_RUNNING);
550 remove_wait_queue(&ctx->stop_wq, &wait);
551 }
552
553 static struct spu *spu_get_idle(struct spu_context *ctx)
554 {
555 struct spu *spu, *aff_ref_spu;
556 int node, n;
557
558 spu_context_nospu_trace(spu_get_idle__enter, ctx);
559
560 if (ctx->gang) {
561 mutex_lock(&ctx->gang->aff_mutex);
562 if (has_affinity(ctx)) {
563 aff_ref_spu = ctx->gang->aff_ref_spu;
564 atomic_inc(&ctx->gang->aff_sched_count);
565 mutex_unlock(&ctx->gang->aff_mutex);
566 node = aff_ref_spu->node;
567
568 mutex_lock(&cbe_spu_info[node].list_mutex);
569 spu = ctx_location(aff_ref_spu, ctx->aff_offset, node);
570 if (spu && spu->alloc_state == SPU_FREE)
571 goto found;
572 mutex_unlock(&cbe_spu_info[node].list_mutex);
573
574 atomic_dec(&ctx->gang->aff_sched_count);
575 goto not_found;
576 }
577 mutex_unlock(&ctx->gang->aff_mutex);
578 }
579 node = cpu_to_node(raw_smp_processor_id());
580 for (n = 0; n < MAX_NUMNODES; n++, node++) {
581 node = (node < MAX_NUMNODES) ? node : 0;
582 if (!node_allowed(ctx, node))
583 continue;
584
585 mutex_lock(&cbe_spu_info[node].list_mutex);
586 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
587 if (spu->alloc_state == SPU_FREE)
588 goto found;
589 }
590 mutex_unlock(&cbe_spu_info[node].list_mutex);
591 }
592
593 not_found:
594 spu_context_nospu_trace(spu_get_idle__not_found, ctx);
595 return NULL;
596
597 found:
598 spu->alloc_state = SPU_USED;
599 mutex_unlock(&cbe_spu_info[node].list_mutex);
600 spu_context_trace(spu_get_idle__found, ctx, spu);
601 spu_init_channels(spu);
602 return spu;
603 }
604
605 /**
606 * find_victim - find a lower priority context to preempt
607 * @ctx: candidate context for running
608 *
609 * Returns the freed physical spu to run the new context on.
610 */
611 static struct spu *find_victim(struct spu_context *ctx)
612 {
613 struct spu_context *victim = NULL;
614 struct spu *spu;
615 int node, n;
616
617 spu_context_nospu_trace(spu_find_victim__enter, ctx);
618
619 /*
620 * Look for a possible preemption candidate on the local node first.
621 * If there is no candidate look at the other nodes. This isn't
622 * exactly fair, but so far the whole spu scheduler tries to keep
623 * a strong node affinity. We might want to fine-tune this in
624 * the future.
625 */
626 restart:
627 node = cpu_to_node(raw_smp_processor_id());
628 for (n = 0; n < MAX_NUMNODES; n++, node++) {
629 node = (node < MAX_NUMNODES) ? node : 0;
630 if (!node_allowed(ctx, node))
631 continue;
632
633 mutex_lock(&cbe_spu_info[node].list_mutex);
634 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
635 struct spu_context *tmp = spu->ctx;
636
637 if (tmp && tmp->prio > ctx->prio &&
638 !(tmp->flags & SPU_CREATE_NOSCHED) &&
639 (!victim || tmp->prio > victim->prio)) {
640 victim = spu->ctx;
641 }
642 }
643 if (victim)
644 get_spu_context(victim);
645 mutex_unlock(&cbe_spu_info[node].list_mutex);
646
647 if (victim) {
648 /*
649 * This nests ctx->state_mutex, but we always lock
650 * higher priority contexts before lower priority
651 * ones, so this is safe until we introduce
652 * priority inheritance schemes.
653 *
654 * XXX if the highest priority context is locked,
655 * this can loop a long time. Might be better to
656 * look at another context or give up after X retries.
657 */
658 if (!mutex_trylock(&victim->state_mutex)) {
659 put_spu_context(victim);
660 victim = NULL;
661 goto restart;
662 }
663
664 spu = victim->spu;
665 if (!spu || victim->prio <= ctx->prio) {
666 /*
667 * This race can happen because we've dropped
668 * the active list mutex. Not a problem, just
669 * restart the search.
670 */
671 mutex_unlock(&victim->state_mutex);
672 put_spu_context(victim);
673 victim = NULL;
674 goto restart;
675 }
676
677 spu_context_trace(__spu_deactivate__unload, ctx, spu);
678
679 mutex_lock(&cbe_spu_info[node].list_mutex);
680 cbe_spu_info[node].nr_active--;
681 spu_unbind_context(spu, victim);
682 mutex_unlock(&cbe_spu_info[node].list_mutex);
683
684 victim->stats.invol_ctx_switch++;
685 spu->stats.invol_ctx_switch++;
686 if (test_bit(SPU_SCHED_SPU_RUN, &victim->sched_flags))
687 spu_add_to_rq(victim);
688
689 mutex_unlock(&victim->state_mutex);
690 put_spu_context(victim);
691
692 return spu;
693 }
694 }
695
696 return NULL;
697 }
698
699 static void __spu_schedule(struct spu *spu, struct spu_context *ctx)
700 {
701 int node = spu->node;
702 int success = 0;
703
704 spu_set_timeslice(ctx);
705
706 mutex_lock(&cbe_spu_info[node].list_mutex);
707 if (spu->ctx == NULL) {
708 spu_bind_context(spu, ctx);
709 cbe_spu_info[node].nr_active++;
710 spu->alloc_state = SPU_USED;
711 success = 1;
712 }
713 mutex_unlock(&cbe_spu_info[node].list_mutex);
714
715 if (success)
716 wake_up_all(&ctx->run_wq);
717 else
718 spu_add_to_rq(ctx);
719 }
720
721 static void spu_schedule(struct spu *spu, struct spu_context *ctx)
722 {
723 /* not a candidate for interruptible because it's called either
724 from the scheduler thread or from spu_deactivate */
725 mutex_lock(&ctx->state_mutex);
726 if (ctx->state == SPU_STATE_SAVED)
727 __spu_schedule(spu, ctx);
728 spu_release(ctx);
729 }
730
731 /**
732 * spu_unschedule - remove a context from a spu, and possibly release it.
733 * @spu: The SPU to unschedule from
734 * @ctx: The context currently scheduled on the SPU
735 * @free_spu Whether to free the SPU for other contexts
736 *
737 * Unbinds the context @ctx from the SPU @spu. If @free_spu is non-zero, the
738 * SPU is made available for other contexts (ie, may be returned by
739 * spu_get_idle). If this is zero, the caller is expected to schedule another
740 * context to this spu.
741 *
742 * Should be called with ctx->state_mutex held.
743 */
744 static void spu_unschedule(struct spu *spu, struct spu_context *ctx,
745 int free_spu)
746 {
747 int node = spu->node;
748
749 mutex_lock(&cbe_spu_info[node].list_mutex);
750 cbe_spu_info[node].nr_active--;
751 if (free_spu)
752 spu->alloc_state = SPU_FREE;
753 spu_unbind_context(spu, ctx);
754 ctx->stats.invol_ctx_switch++;
755 spu->stats.invol_ctx_switch++;
756 mutex_unlock(&cbe_spu_info[node].list_mutex);
757 }
758
759 /**
760 * spu_activate - find a free spu for a context and execute it
761 * @ctx: spu context to schedule
762 * @flags: flags (currently ignored)
763 *
764 * Tries to find a free spu to run @ctx. If no free spu is available
765 * add the context to the runqueue so it gets woken up once an spu
766 * is available.
767 */
768 int spu_activate(struct spu_context *ctx, unsigned long flags)
769 {
770 struct spu *spu;
771
772 /*
773 * If there are multiple threads waiting for a single context
774 * only one actually binds the context while the others will
775 * only be able to acquire the state_mutex once the context
776 * already is in runnable state.
777 */
778 if (ctx->spu)
779 return 0;
780
781 spu_activate_top:
782 if (signal_pending(current))
783 return -ERESTARTSYS;
784
785 spu = spu_get_idle(ctx);
786 /*
787 * If this is a realtime thread we try to get it running by
788 * preempting a lower priority thread.
789 */
790 if (!spu && rt_prio(ctx->prio))
791 spu = find_victim(ctx);
792 if (spu) {
793 unsigned long runcntl;
794
795 runcntl = ctx->ops->runcntl_read(ctx);
796 __spu_schedule(spu, ctx);
797 if (runcntl & SPU_RUNCNTL_RUNNABLE)
798 spuctx_switch_state(ctx, SPU_UTIL_USER);
799
800 return 0;
801 }
802
803 if (ctx->flags & SPU_CREATE_NOSCHED) {
804 spu_prio_wait(ctx);
805 goto spu_activate_top;
806 }
807
808 spu_add_to_rq(ctx);
809
810 return 0;
811 }
812
813 /**
814 * grab_runnable_context - try to find a runnable context
815 *
816 * Remove the highest priority context on the runqueue and return it
817 * to the caller. Returns %NULL if no runnable context was found.
818 */
819 static struct spu_context *grab_runnable_context(int prio, int node)
820 {
821 struct spu_context *ctx;
822 int best;
823
824 spin_lock(&spu_prio->runq_lock);
825 best = find_first_bit(spu_prio->bitmap, prio);
826 while (best < prio) {
827 struct list_head *rq = &spu_prio->runq[best];
828
829 list_for_each_entry(ctx, rq, rq) {
830 /* XXX(hch): check for affinity here as well */
831 if (__node_allowed(ctx, node)) {
832 __spu_del_from_rq(ctx);
833 goto found;
834 }
835 }
836 best++;
837 }
838 ctx = NULL;
839 found:
840 spin_unlock(&spu_prio->runq_lock);
841 return ctx;
842 }
843
844 static int __spu_deactivate(struct spu_context *ctx, int force, int max_prio)
845 {
846 struct spu *spu = ctx->spu;
847 struct spu_context *new = NULL;
848
849 if (spu) {
850 new = grab_runnable_context(max_prio, spu->node);
851 if (new || force) {
852 spu_unschedule(spu, ctx, new == NULL);
853 if (new) {
854 if (new->flags & SPU_CREATE_NOSCHED)
855 wake_up(&new->stop_wq);
856 else {
857 spu_release(ctx);
858 spu_schedule(spu, new);
859 /* this one can't easily be made
860 interruptible */
861 mutex_lock(&ctx->state_mutex);
862 }
863 }
864 }
865 }
866
867 return new != NULL;
868 }
869
870 /**
871 * spu_deactivate - unbind a context from its physical spu
872 * @ctx: spu context to unbind
873 *
874 * Unbind @ctx from the physical spu it is running on and schedule
875 * the highest priority context to run on the freed physical spu.
876 */
877 void spu_deactivate(struct spu_context *ctx)
878 {
879 spu_context_nospu_trace(spu_deactivate__enter, ctx);
880 __spu_deactivate(ctx, 1, MAX_PRIO);
881 }
882
883 /**
884 * spu_yield - yield a physical spu if others are waiting
885 * @ctx: spu context to yield
886 *
887 * Check if there is a higher priority context waiting and if yes
888 * unbind @ctx from the physical spu and schedule the highest
889 * priority context to run on the freed physical spu instead.
890 */
891 void spu_yield(struct spu_context *ctx)
892 {
893 spu_context_nospu_trace(spu_yield__enter, ctx);
894 if (!(ctx->flags & SPU_CREATE_NOSCHED)) {
895 mutex_lock(&ctx->state_mutex);
896 __spu_deactivate(ctx, 0, MAX_PRIO);
897 mutex_unlock(&ctx->state_mutex);
898 }
899 }
900
901 static noinline void spusched_tick(struct spu_context *ctx)
902 {
903 struct spu_context *new = NULL;
904 struct spu *spu = NULL;
905
906 if (spu_acquire(ctx))
907 BUG(); /* a kernel thread never has signals pending */
908
909 if (ctx->state != SPU_STATE_RUNNABLE)
910 goto out;
911 if (ctx->flags & SPU_CREATE_NOSCHED)
912 goto out;
913 if (ctx->policy == SCHED_FIFO)
914 goto out;
915
916 if (--ctx->time_slice && test_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags))
917 goto out;
918
919 spu = ctx->spu;
920
921 spu_context_trace(spusched_tick__preempt, ctx, spu);
922
923 new = grab_runnable_context(ctx->prio + 1, spu->node);
924 if (new) {
925 spu_unschedule(spu, ctx, 0);
926 if (test_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags))
927 spu_add_to_rq(ctx);
928 } else {
929 spu_context_nospu_trace(spusched_tick__newslice, ctx);
930 if (!ctx->time_slice)
931 ctx->time_slice++;
932 }
933 out:
934 spu_release(ctx);
935
936 if (new)
937 spu_schedule(spu, new);
938 }
939
940 /**
941 * count_active_contexts - count nr of active tasks
942 *
943 * Return the number of tasks currently running or waiting to run.
944 *
945 * Note that we don't take runq_lock / list_mutex here. Reading
946 * a single 32bit value is atomic on powerpc, and we don't care
947 * about memory ordering issues here.
948 */
949 static unsigned long count_active_contexts(void)
950 {
951 int nr_active = 0, node;
952
953 for (node = 0; node < MAX_NUMNODES; node++)
954 nr_active += cbe_spu_info[node].nr_active;
955 nr_active += spu_prio->nr_waiting;
956
957 return nr_active;
958 }
959
960 /**
961 * spu_calc_load - update the avenrun load estimates.
962 *
963 * No locking against reading these values from userspace, as for
964 * the CPU loadavg code.
965 */
966 static void spu_calc_load(void)
967 {
968 unsigned long active_tasks; /* fixed-point */
969
970 active_tasks = count_active_contexts() * FIXED_1;
971 spu_avenrun[0] = calc_load(spu_avenrun[0], EXP_1, active_tasks);
972 spu_avenrun[1] = calc_load(spu_avenrun[1], EXP_5, active_tasks);
973 spu_avenrun[2] = calc_load(spu_avenrun[2], EXP_15, active_tasks);
974 }
975
976 static void spusched_wake(struct timer_list *unused)
977 {
978 mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
979 wake_up_process(spusched_task);
980 }
981
982 static void spuloadavg_wake(struct timer_list *unused)
983 {
984 mod_timer(&spuloadavg_timer, jiffies + LOAD_FREQ);
985 spu_calc_load();
986 }
987
988 static int spusched_thread(void *unused)
989 {
990 struct spu *spu;
991 int node;
992
993 while (!kthread_should_stop()) {
994 set_current_state(TASK_INTERRUPTIBLE);
995 schedule();
996 for (node = 0; node < MAX_NUMNODES; node++) {
997 struct mutex *mtx = &cbe_spu_info[node].list_mutex;
998
999 mutex_lock(mtx);
1000 list_for_each_entry(spu, &cbe_spu_info[node].spus,
1001 cbe_list) {
1002 struct spu_context *ctx = spu->ctx;
1003
1004 if (ctx) {
1005 get_spu_context(ctx);
1006 mutex_unlock(mtx);
1007 spusched_tick(ctx);
1008 mutex_lock(mtx);
1009 put_spu_context(ctx);
1010 }
1011 }
1012 mutex_unlock(mtx);
1013 }
1014 }
1015
1016 return 0;
1017 }
1018
1019 void spuctx_switch_state(struct spu_context *ctx,
1020 enum spu_utilization_state new_state)
1021 {
1022 unsigned long long curtime;
1023 signed long long delta;
1024 struct spu *spu;
1025 enum spu_utilization_state old_state;
1026 int node;
1027
1028 curtime = ktime_get_ns();
1029 delta = curtime - ctx->stats.tstamp;
1030
1031 WARN_ON(!mutex_is_locked(&ctx->state_mutex));
1032 WARN_ON(delta < 0);
1033
1034 spu = ctx->spu;
1035 old_state = ctx->stats.util_state;
1036 ctx->stats.util_state = new_state;
1037 ctx->stats.tstamp = curtime;
1038
1039 /*
1040 * Update the physical SPU utilization statistics.
1041 */
1042 if (spu) {
1043 ctx->stats.times[old_state] += delta;
1044 spu->stats.times[old_state] += delta;
1045 spu->stats.util_state = new_state;
1046 spu->stats.tstamp = curtime;
1047 node = spu->node;
1048 if (old_state == SPU_UTIL_USER)
1049 atomic_dec(&cbe_spu_info[node].busy_spus);
1050 if (new_state == SPU_UTIL_USER)
1051 atomic_inc(&cbe_spu_info[node].busy_spus);
1052 }
1053 }
1054
1055 #ifdef CONFIG_PROC_FS
1056 static int show_spu_loadavg(struct seq_file *s, void *private)
1057 {
1058 int a, b, c;
1059
1060 a = spu_avenrun[0] + (FIXED_1/200);
1061 b = spu_avenrun[1] + (FIXED_1/200);
1062 c = spu_avenrun[2] + (FIXED_1/200);
1063
1064 /*
1065 * Note that last_pid doesn't really make much sense for the
1066 * SPU loadavg (it even seems very odd on the CPU side...),
1067 * but we include it here to have a 100% compatible interface.
1068 */
1069 seq_printf(s, "%d.%02d %d.%02d %d.%02d %ld/%d %d\n",
1070 LOAD_INT(a), LOAD_FRAC(a),
1071 LOAD_INT(b), LOAD_FRAC(b),
1072 LOAD_INT(c), LOAD_FRAC(c),
1073 count_active_contexts(),
1074 atomic_read(&nr_spu_contexts),
1075 idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
1076 return 0;
1077 }
1078 #endif
1079
1080 int __init spu_sched_init(void)
1081 {
1082 struct proc_dir_entry *entry;
1083 int err = -ENOMEM, i;
1084
1085 spu_prio = kzalloc(sizeof(struct spu_prio_array), GFP_KERNEL);
1086 if (!spu_prio)
1087 goto out;
1088
1089 for (i = 0; i < MAX_PRIO; i++) {
1090 INIT_LIST_HEAD(&spu_prio->runq[i]);
1091 __clear_bit(i, spu_prio->bitmap);
1092 }
1093 spin_lock_init(&spu_prio->runq_lock);
1094
1095 timer_setup(&spusched_timer, spusched_wake, 0);
1096 timer_setup(&spuloadavg_timer, spuloadavg_wake, 0);
1097
1098 spusched_task = kthread_run(spusched_thread, NULL, "spusched");
1099 if (IS_ERR(spusched_task)) {
1100 err = PTR_ERR(spusched_task);
1101 goto out_free_spu_prio;
1102 }
1103
1104 mod_timer(&spuloadavg_timer, 0);
1105
1106 entry = proc_create_single("spu_loadavg", 0, NULL, show_spu_loadavg);
1107 if (!entry)
1108 goto out_stop_kthread;
1109
1110 pr_debug("spusched: tick: %d, min ticks: %d, default ticks: %d\n",
1111 SPUSCHED_TICK, MIN_SPU_TIMESLICE, DEF_SPU_TIMESLICE);
1112 return 0;
1113
1114 out_stop_kthread:
1115 kthread_stop(spusched_task);
1116 out_free_spu_prio:
1117 kfree(spu_prio);
1118 out:
1119 return err;
1120 }
1121
1122 void spu_sched_exit(void)
1123 {
1124 struct spu *spu;
1125 int node;
1126
1127 remove_proc_entry("spu_loadavg", NULL);
1128
1129 del_timer_sync(&spusched_timer);
1130 del_timer_sync(&spuloadavg_timer);
1131 kthread_stop(spusched_task);
1132
1133 for (node = 0; node < MAX_NUMNODES; node++) {
1134 mutex_lock(&cbe_spu_info[node].list_mutex);
1135 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list)
1136 if (spu->alloc_state != SPU_FREE)
1137 spu->alloc_state = SPU_FREE;
1138 mutex_unlock(&cbe_spu_info[node].list_mutex);
1139 }
1140 kfree(spu_prio);
1141 }
1142
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.