root/arch/powerpc/platforms/cell/spufs/sched.c

DEFINITIONS

1. spu_set_timeslice
2. __spu_update_sched_info
3. spu_update_sched_info
4. __node_allowed
5. node_allowed
6. do_notify_spus_active
7. spu_bind_context
8. sched_spu
9. aff_merge_remaining_ctxs
10. aff_set_offsets
11. aff_ref_location
12. aff_set_ref_point_location
13. ctx_location
14. has_affinity
15. spu_unbind_context
16. __spu_add_to_rq
17. spu_add_to_rq
18. __spu_del_from_rq
19. spu_del_from_rq
20. spu_prio_wait
21. spu_get_idle
22. find_victim
23. __spu_schedule
24. spu_schedule
25. spu_unschedule
26. spu_activate
27. grab_runnable_context
28. __spu_deactivate
29. spu_deactivate
30. spu_yield
31. spusched_tick
32. count_active_contexts
33. spu_calc_load
34. spusched_wake
35. spuloadavg_wake
36. spusched_thread
37. spuctx_switch_state
38. show_spu_loadavg
39. spu_sched_init
40. spu_sched_exit

   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) / (MAX_USER_PRIO / 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          * When the awakened processes see their "notify_active" flag is set,
 186          * they will call spu_switch_notify().
 187          */
 188         for_each_online_node(node) {
 189                 struct spu *spu;
 190 
 191                 mutex_lock(&cbe_spu_info[node].list_mutex);
 192                 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
 193                         if (spu->alloc_state != SPU_FREE) {
 194                                 struct spu_context *ctx = spu->ctx;
 195                                 set_bit(SPU_SCHED_NOTIFY_ACTIVE,
 196                                         &ctx->sched_flags);
 197                                 mb();
 198                                 wake_up_all(&ctx->stop_wq);
 199                         }
 200                 }
 201                 mutex_unlock(&cbe_spu_info[node].list_mutex);
 202         }
 203 }
 204 
 205 /**
 206  * spu_bind_context - bind spu context to physical spu
 207  * @spu:        physical spu to bind to
 208  * @ctx:        context to bind
 209  */
 210 static void spu_bind_context(struct spu *spu, struct spu_context *ctx)
 211 {
 212         spu_context_trace(spu_bind_context__enter, ctx, spu);
 213 
 214         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 215 
 216         if (ctx->flags & SPU_CREATE_NOSCHED)
 217                 atomic_inc(&cbe_spu_info[spu->node].reserved_spus);
 218 
 219         ctx->stats.slb_flt_base = spu->stats.slb_flt;
 220         ctx->stats.class2_intr_base = spu->stats.class2_intr;
 221 
 222         spu_associate_mm(spu, ctx->owner);
 223 
 224         spin_lock_irq(&spu->register_lock);
 225         spu->ctx = ctx;
 226         spu->flags = 0;
 227         ctx->spu = spu;
 228         ctx->ops = &spu_hw_ops;
 229         spu->pid = current->pid;
 230         spu->tgid = current->tgid;
 231         spu->ibox_callback = spufs_ibox_callback;
 232         spu->wbox_callback = spufs_wbox_callback;
 233         spu->stop_callback = spufs_stop_callback;
 234         spu->mfc_callback = spufs_mfc_callback;
 235         spin_unlock_irq(&spu->register_lock);
 236 
 237         spu_unmap_mappings(ctx);
 238 
 239         spu_switch_log_notify(spu, ctx, SWITCH_LOG_START, 0);
 240         spu_restore(&ctx->csa, spu);
 241         spu->timestamp = jiffies;
 242         spu_switch_notify(spu, ctx);
 243         ctx->state = SPU_STATE_RUNNABLE;
 244 
 245         spuctx_switch_state(ctx, SPU_UTIL_USER);
 246 }
 247 
 248 /*
 249  * Must be used with the list_mutex held.
 250  */
 251 static inline int sched_spu(struct spu *spu)
 252 {
 253         BUG_ON(!mutex_is_locked(&cbe_spu_info[spu->node].list_mutex));
 254 
 255         return (!spu->ctx || !(spu->ctx->flags & SPU_CREATE_NOSCHED));
 256 }
 257 
 258 static void aff_merge_remaining_ctxs(struct spu_gang *gang)
 259 {
 260         struct spu_context *ctx;
 261 
 262         list_for_each_entry(ctx, &gang->aff_list_head, aff_list) {
 263                 if (list_empty(&ctx->aff_list))
 264                         list_add(&ctx->aff_list, &gang->aff_list_head);
 265         }
 266         gang->aff_flags |= AFF_MERGED;
 267 }
 268 
 269 static void aff_set_offsets(struct spu_gang *gang)
 270 {
 271         struct spu_context *ctx;
 272         int offset;
 273 
 274         offset = -1;
 275         list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list,
 276                                                                 aff_list) {
 277                 if (&ctx->aff_list == &gang->aff_list_head)
 278                         break;
 279                 ctx->aff_offset = offset--;
 280         }
 281 
 282         offset = 0;
 283         list_for_each_entry(ctx, gang->aff_ref_ctx->aff_list.prev, aff_list) {
 284                 if (&ctx->aff_list == &gang->aff_list_head)
 285                         break;
 286                 ctx->aff_offset = offset++;
 287         }
 288 
 289         gang->aff_flags |= AFF_OFFSETS_SET;
 290 }
 291 
 292 static struct spu *aff_ref_location(struct spu_context *ctx, int mem_aff,
 293                  int group_size, int lowest_offset)
 294 {
 295         struct spu *spu;
 296         int node, n;
 297 
 298         /*
 299          * TODO: A better algorithm could be used to find a good spu to be
 300          *       used as reference location for the ctxs chain.
 301          */
 302         node = cpu_to_node(raw_smp_processor_id());
 303         for (n = 0; n < MAX_NUMNODES; n++, node++) {
 304                 /*
 305                  * "available_spus" counts how many spus are not potentially
 306                  * going to be used by other affinity gangs whose reference
 307                  * context is already in place. Although this code seeks to
 308                  * avoid having affinity gangs with a summed amount of
 309                  * contexts bigger than the amount of spus in the node,
 310                  * this may happen sporadically. In this case, available_spus
 311                  * becomes negative, which is harmless.
 312                  */
 313                 int available_spus;
 314 
 315                 node = (node < MAX_NUMNODES) ? node : 0;
 316                 if (!node_allowed(ctx, node))
 317                         continue;
 318 
 319                 available_spus = 0;
 320                 mutex_lock(&cbe_spu_info[node].list_mutex);
 321                 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
 322                         if (spu->ctx && spu->ctx->gang && !spu->ctx->aff_offset
 323                                         && spu->ctx->gang->aff_ref_spu)
 324                                 available_spus -= spu->ctx->gang->contexts;
 325                         available_spus++;
 326                 }
 327                 if (available_spus < ctx->gang->contexts) {
 328                         mutex_unlock(&cbe_spu_info[node].list_mutex);
 329                         continue;
 330                 }
 331 
 332                 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
 333                         if ((!mem_aff || spu->has_mem_affinity) &&
 334                                                         sched_spu(spu)) {
 335                                 mutex_unlock(&cbe_spu_info[node].list_mutex);
 336                                 return spu;
 337                         }
 338                 }
 339                 mutex_unlock(&cbe_spu_info[node].list_mutex);
 340         }
 341         return NULL;
 342 }
 343 
 344 static void aff_set_ref_point_location(struct spu_gang *gang)
 345 {
 346         int mem_aff, gs, lowest_offset;
 347         struct spu_context *ctx;
 348         struct spu *tmp;
 349 
 350         mem_aff = gang->aff_ref_ctx->flags & SPU_CREATE_AFFINITY_MEM;
 351         lowest_offset = 0;
 352         gs = 0;
 353 
 354         list_for_each_entry(tmp, &gang->aff_list_head, aff_list)
 355                 gs++;
 356 
 357         list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list,
 358                                                                 aff_list) {
 359                 if (&ctx->aff_list == &gang->aff_list_head)
 360                         break;
 361                 lowest_offset = ctx->aff_offset;
 362         }
 363 
 364         gang->aff_ref_spu = aff_ref_location(gang->aff_ref_ctx, mem_aff, gs,
 365                                                         lowest_offset);
 366 }
 367 
 368 static struct spu *ctx_location(struct spu *ref, int offset, int node)
 369 {
 370         struct spu *spu;
 371 
 372         spu = NULL;
 373         if (offset >= 0) {
 374                 list_for_each_entry(spu, ref->aff_list.prev, aff_list) {
 375                         BUG_ON(spu->node != node);
 376                         if (offset == 0)
 377                                 break;
 378                         if (sched_spu(spu))
 379                                 offset--;
 380                 }
 381         } else {
 382                 list_for_each_entry_reverse(spu, ref->aff_list.next, aff_list) {
 383                         BUG_ON(spu->node != node);
 384                         if (offset == 0)
 385                                 break;
 386                         if (sched_spu(spu))
 387                                 offset++;
 388                 }
 389         }
 390 
 391         return spu;
 392 }
 393 
 394 /*
 395  * affinity_check is called each time a context is going to be scheduled.
 396  * It returns the spu ptr on which the context must run.
 397  */
 398 static int has_affinity(struct spu_context *ctx)
 399 {
 400         struct spu_gang *gang = ctx->gang;
 401 
 402         if (list_empty(&ctx->aff_list))
 403                 return 0;
 404 
 405         if (atomic_read(&ctx->gang->aff_sched_count) == 0)
 406                 ctx->gang->aff_ref_spu = NULL;
 407 
 408         if (!gang->aff_ref_spu) {
 409                 if (!(gang->aff_flags & AFF_MERGED))
 410                         aff_merge_remaining_ctxs(gang);
 411                 if (!(gang->aff_flags & AFF_OFFSETS_SET))
 412                         aff_set_offsets(gang);
 413                 aff_set_ref_point_location(gang);
 414         }
 415 
 416         return gang->aff_ref_spu != NULL;
 417 }
 418 
 419 /**
 420  * spu_unbind_context - unbind spu context from physical spu
 421  * @spu:        physical spu to unbind from
 422  * @ctx:        context to unbind
 423  */
 424 static void spu_unbind_context(struct spu *spu, struct spu_context *ctx)
 425 {
 426         u32 status;
 427 
 428         spu_context_trace(spu_unbind_context__enter, ctx, spu);
 429 
 430         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 431 
 432         if (spu->ctx->flags & SPU_CREATE_NOSCHED)
 433                 atomic_dec(&cbe_spu_info[spu->node].reserved_spus);
 434 
 435         if (ctx->gang)
 436                 /*
 437                  * If ctx->gang->aff_sched_count is positive, SPU affinity is
 438                  * being considered in this gang. Using atomic_dec_if_positive
 439                  * allow us to skip an explicit check for affinity in this gang
 440                  */
 441                 atomic_dec_if_positive(&ctx->gang->aff_sched_count);
 442 
 443         spu_switch_notify(spu, NULL);
 444         spu_unmap_mappings(ctx);
 445         spu_save(&ctx->csa, spu);
 446         spu_switch_log_notify(spu, ctx, SWITCH_LOG_STOP, 0);
 447 
 448         spin_lock_irq(&spu->register_lock);
 449         spu->timestamp = jiffies;
 450         ctx->state = SPU_STATE_SAVED;
 451         spu->ibox_callback = NULL;
 452         spu->wbox_callback = NULL;
 453         spu->stop_callback = NULL;
 454         spu->mfc_callback = NULL;
 455         spu->pid = 0;
 456         spu->tgid = 0;
 457         ctx->ops = &spu_backing_ops;
 458         spu->flags = 0;
 459         spu->ctx = NULL;
 460         spin_unlock_irq(&spu->register_lock);
 461 
 462         spu_associate_mm(spu, NULL);
 463 
 464         ctx->stats.slb_flt +=
 465                 (spu->stats.slb_flt - ctx->stats.slb_flt_base);
 466         ctx->stats.class2_intr +=
 467                 (spu->stats.class2_intr - ctx->stats.class2_intr_base);
 468 
 469         /* This maps the underlying spu state to idle */
 470         spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
 471         ctx->spu = NULL;
 472 
 473         if (spu_stopped(ctx, &status))
 474                 wake_up_all(&ctx->stop_wq);
 475 }
 476 
 477 /**
 478  * spu_add_to_rq - add a context to the runqueue
 479  * @ctx:       context to add
 480  */
 481 static void __spu_add_to_rq(struct spu_context *ctx)
 482 {
 483         /*
 484          * Unfortunately this code path can be called from multiple threads
 485          * on behalf of a single context due to the way the problem state
 486          * mmap support works.
 487          *
 488          * Fortunately we need to wake up all these threads at the same time
 489          * and can simply skip the runqueue addition for every but the first
 490          * thread getting into this codepath.
 491          *
 492          * It's still quite hacky, and long-term we should proxy all other
 493          * threads through the owner thread so that spu_run is in control
 494          * of all the scheduling activity for a given context.
 495          */
 496         if (list_empty(&ctx->rq)) {
 497                 list_add_tail(&ctx->rq, &spu_prio->runq[ctx->prio]);
 498                 set_bit(ctx->prio, spu_prio->bitmap);
 499                 if (!spu_prio->nr_waiting++)
 500                         mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
 501         }
 502 }
 503 
 504 static void spu_add_to_rq(struct spu_context *ctx)
 505 {
 506         spin_lock(&spu_prio->runq_lock);
 507         __spu_add_to_rq(ctx);
 508         spin_unlock(&spu_prio->runq_lock);
 509 }
 510 
 511 static void __spu_del_from_rq(struct spu_context *ctx)
 512 {
 513         int prio = ctx->prio;
 514 
 515         if (!list_empty(&ctx->rq)) {
 516                 if (!--spu_prio->nr_waiting)
 517                         del_timer(&spusched_timer);
 518                 list_del_init(&ctx->rq);
 519 
 520                 if (list_empty(&spu_prio->runq[prio]))
 521                         clear_bit(prio, spu_prio->bitmap);
 522         }
 523 }
 524 
 525 void spu_del_from_rq(struct spu_context *ctx)
 526 {
 527         spin_lock(&spu_prio->runq_lock);
 528         __spu_del_from_rq(ctx);
 529         spin_unlock(&spu_prio->runq_lock);
 530 }
 531 
 532 static void spu_prio_wait(struct spu_context *ctx)
 533 {
 534         DEFINE_WAIT(wait);
 535 
 536         /*
 537          * The caller must explicitly wait for a context to be loaded
 538          * if the nosched flag is set.  If NOSCHED is not set, the caller
 539          * queues the context and waits for an spu event or error.
 540          */
 541         BUG_ON(!(ctx->flags & SPU_CREATE_NOSCHED));
 542 
 543         spin_lock(&spu_prio->runq_lock);
 544         prepare_to_wait_exclusive(&ctx->stop_wq, &wait, TASK_INTERRUPTIBLE);
 545         if (!signal_pending(current)) {
 546                 __spu_add_to_rq(ctx);
 547                 spin_unlock(&spu_prio->runq_lock);
 548                 mutex_unlock(&ctx->state_mutex);
 549                 schedule();
 550                 mutex_lock(&ctx->state_mutex);
 551                 spin_lock(&spu_prio->runq_lock);
 552                 __spu_del_from_rq(ctx);
 553         }
 554         spin_unlock(&spu_prio->runq_lock);
 555         __set_current_state(TASK_RUNNING);
 556         remove_wait_queue(&ctx->stop_wq, &wait);
 557 }
 558 
 559 static struct spu *spu_get_idle(struct spu_context *ctx)
 560 {
 561         struct spu *spu, *aff_ref_spu;
 562         int node, n;
 563 
 564         spu_context_nospu_trace(spu_get_idle__enter, ctx);
 565 
 566         if (ctx->gang) {
 567                 mutex_lock(&ctx->gang->aff_mutex);
 568                 if (has_affinity(ctx)) {
 569                         aff_ref_spu = ctx->gang->aff_ref_spu;
 570                         atomic_inc(&ctx->gang->aff_sched_count);
 571                         mutex_unlock(&ctx->gang->aff_mutex);
 572                         node = aff_ref_spu->node;
 573 
 574                         mutex_lock(&cbe_spu_info[node].list_mutex);
 575                         spu = ctx_location(aff_ref_spu, ctx->aff_offset, node);
 576                         if (spu && spu->alloc_state == SPU_FREE)
 577                                 goto found;
 578                         mutex_unlock(&cbe_spu_info[node].list_mutex);
 579 
 580                         atomic_dec(&ctx->gang->aff_sched_count);
 581                         goto not_found;
 582                 }
 583                 mutex_unlock(&ctx->gang->aff_mutex);
 584         }
 585         node = cpu_to_node(raw_smp_processor_id());
 586         for (n = 0; n < MAX_NUMNODES; n++, node++) {
 587                 node = (node < MAX_NUMNODES) ? node : 0;
 588                 if (!node_allowed(ctx, node))
 589                         continue;
 590 
 591                 mutex_lock(&cbe_spu_info[node].list_mutex);
 592                 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
 593                         if (spu->alloc_state == SPU_FREE)
 594                                 goto found;
 595                 }
 596                 mutex_unlock(&cbe_spu_info[node].list_mutex);
 597         }
 598 
 599  not_found:
 600         spu_context_nospu_trace(spu_get_idle__not_found, ctx);
 601         return NULL;
 602 
 603  found:
 604         spu->alloc_state = SPU_USED;
 605         mutex_unlock(&cbe_spu_info[node].list_mutex);
 606         spu_context_trace(spu_get_idle__found, ctx, spu);
 607         spu_init_channels(spu);
 608         return spu;
 609 }
 610 
 611 /**
 612  * find_victim - find a lower priority context to preempt
 613  * @ctx:        candidate context for running
 614  *
 615  * Returns the freed physical spu to run the new context on.
 616  */
 617 static struct spu *find_victim(struct spu_context *ctx)
 618 {
 619         struct spu_context *victim = NULL;
 620         struct spu *spu;
 621         int node, n;
 622 
 623         spu_context_nospu_trace(spu_find_victim__enter, ctx);
 624 
 625         /*
 626          * Look for a possible preemption candidate on the local node first.
 627          * If there is no candidate look at the other nodes.  This isn't
 628          * exactly fair, but so far the whole spu scheduler tries to keep
 629          * a strong node affinity.  We might want to fine-tune this in
 630          * the future.
 631          */
 632  restart:
 633         node = cpu_to_node(raw_smp_processor_id());
 634         for (n = 0; n < MAX_NUMNODES; n++, node++) {
 635                 node = (node < MAX_NUMNODES) ? node : 0;
 636                 if (!node_allowed(ctx, node))
 637                         continue;
 638 
 639                 mutex_lock(&cbe_spu_info[node].list_mutex);
 640                 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
 641                         struct spu_context *tmp = spu->ctx;
 642 
 643                         if (tmp && tmp->prio > ctx->prio &&
 644                             !(tmp->flags & SPU_CREATE_NOSCHED) &&
 645                             (!victim || tmp->prio > victim->prio)) {
 646                                 victim = spu->ctx;
 647                         }
 648                 }
 649                 if (victim)
 650                         get_spu_context(victim);
 651                 mutex_unlock(&cbe_spu_info[node].list_mutex);
 652 
 653                 if (victim) {
 654                         /*
 655                          * This nests ctx->state_mutex, but we always lock
 656                          * higher priority contexts before lower priority
 657                          * ones, so this is safe until we introduce
 658                          * priority inheritance schemes.
 659                          *
 660                          * XXX if the highest priority context is locked,
 661                          * this can loop a long time.  Might be better to
 662                          * look at another context or give up after X retries.
 663                          */
 664                         if (!mutex_trylock(&victim->state_mutex)) {
 665                                 put_spu_context(victim);
 666                                 victim = NULL;
 667                                 goto restart;
 668                         }
 669 
 670                         spu = victim->spu;
 671                         if (!spu || victim->prio <= ctx->prio) {
 672                                 /*
 673                                  * This race can happen because we've dropped
 674                                  * the active list mutex.  Not a problem, just
 675                                  * restart the search.
 676                                  */
 677                                 mutex_unlock(&victim->state_mutex);
 678                                 put_spu_context(victim);
 679                                 victim = NULL;
 680                                 goto restart;
 681                         }
 682 
 683                         spu_context_trace(__spu_deactivate__unload, ctx, spu);
 684 
 685                         mutex_lock(&cbe_spu_info[node].list_mutex);
 686                         cbe_spu_info[node].nr_active--;
 687                         spu_unbind_context(spu, victim);
 688                         mutex_unlock(&cbe_spu_info[node].list_mutex);
 689 
 690                         victim->stats.invol_ctx_switch++;
 691                         spu->stats.invol_ctx_switch++;
 692                         if (test_bit(SPU_SCHED_SPU_RUN, &victim->sched_flags))
 693                                 spu_add_to_rq(victim);
 694 
 695                         mutex_unlock(&victim->state_mutex);
 696                         put_spu_context(victim);
 697 
 698                         return spu;
 699                 }
 700         }
 701 
 702         return NULL;
 703 }
 704 
 705 static void __spu_schedule(struct spu *spu, struct spu_context *ctx)
 706 {
 707         int node = spu->node;
 708         int success = 0;
 709 
 710         spu_set_timeslice(ctx);
 711 
 712         mutex_lock(&cbe_spu_info[node].list_mutex);
 713         if (spu->ctx == NULL) {
 714                 spu_bind_context(spu, ctx);
 715                 cbe_spu_info[node].nr_active++;
 716                 spu->alloc_state = SPU_USED;
 717                 success = 1;
 718         }
 719         mutex_unlock(&cbe_spu_info[node].list_mutex);
 720 
 721         if (success)
 722                 wake_up_all(&ctx->run_wq);
 723         else
 724                 spu_add_to_rq(ctx);
 725 }
 726 
 727 static void spu_schedule(struct spu *spu, struct spu_context *ctx)
 728 {
 729         /* not a candidate for interruptible because it's called either
 730            from the scheduler thread or from spu_deactivate */
 731         mutex_lock(&ctx->state_mutex);
 732         if (ctx->state == SPU_STATE_SAVED)
 733                 __spu_schedule(spu, ctx);
 734         spu_release(ctx);
 735 }
 736 
 737 /**
 738  * spu_unschedule - remove a context from a spu, and possibly release it.
 739  * @spu:        The SPU to unschedule from
 740  * @ctx:        The context currently scheduled on the SPU
 741  * @free_spu    Whether to free the SPU for other contexts
 742  *
 743  * Unbinds the context @ctx from the SPU @spu. If @free_spu is non-zero, the
 744  * SPU is made available for other contexts (ie, may be returned by
 745  * spu_get_idle). If this is zero, the caller is expected to schedule another
 746  * context to this spu.
 747  *
 748  * Should be called with ctx->state_mutex held.
 749  */
 750 static void spu_unschedule(struct spu *spu, struct spu_context *ctx,
 751                 int free_spu)
 752 {
 753         int node = spu->node;
 754 
 755         mutex_lock(&cbe_spu_info[node].list_mutex);
 756         cbe_spu_info[node].nr_active--;
 757         if (free_spu)
 758                 spu->alloc_state = SPU_FREE;
 759         spu_unbind_context(spu, ctx);
 760         ctx->stats.invol_ctx_switch++;
 761         spu->stats.invol_ctx_switch++;
 762         mutex_unlock(&cbe_spu_info[node].list_mutex);
 763 }
 764 
 765 /**
 766  * spu_activate - find a free spu for a context and execute it
 767  * @ctx:        spu context to schedule
 768  * @flags:      flags (currently ignored)
 769  *
 770  * Tries to find a free spu to run @ctx.  If no free spu is available
 771  * add the context to the runqueue so it gets woken up once an spu
 772  * is available.
 773  */
 774 int spu_activate(struct spu_context *ctx, unsigned long flags)
 775 {
 776         struct spu *spu;
 777 
 778         /*
 779          * If there are multiple threads waiting for a single context
 780          * only one actually binds the context while the others will
 781          * only be able to acquire the state_mutex once the context
 782          * already is in runnable state.
 783          */
 784         if (ctx->spu)
 785                 return 0;
 786 
 787 spu_activate_top:
 788         if (signal_pending(current))
 789                 return -ERESTARTSYS;
 790 
 791         spu = spu_get_idle(ctx);
 792         /*
 793          * If this is a realtime thread we try to get it running by
 794          * preempting a lower priority thread.
 795          */
 796         if (!spu && rt_prio(ctx->prio))
 797                 spu = find_victim(ctx);
 798         if (spu) {
 799                 unsigned long runcntl;
 800 
 801                 runcntl = ctx->ops->runcntl_read(ctx);
 802                 __spu_schedule(spu, ctx);
 803                 if (runcntl & SPU_RUNCNTL_RUNNABLE)
 804                         spuctx_switch_state(ctx, SPU_UTIL_USER);
 805 
 806                 return 0;
 807         }
 808 
 809         if (ctx->flags & SPU_CREATE_NOSCHED) {
 810                 spu_prio_wait(ctx);
 811                 goto spu_activate_top;
 812         }
 813 
 814         spu_add_to_rq(ctx);
 815 
 816         return 0;
 817 }
 818 
 819 /**
 820  * grab_runnable_context - try to find a runnable context
 821  *
 822  * Remove the highest priority context on the runqueue and return it
 823  * to the caller.  Returns %NULL if no runnable context was found.
 824  */
 825 static struct spu_context *grab_runnable_context(int prio, int node)
 826 {
 827         struct spu_context *ctx;
 828         int best;
 829 
 830         spin_lock(&spu_prio->runq_lock);
 831         best = find_first_bit(spu_prio->bitmap, prio);
 832         while (best < prio) {
 833                 struct list_head *rq = &spu_prio->runq[best];
 834 
 835                 list_for_each_entry(ctx, rq, rq) {
 836                         /* XXX(hch): check for affinity here as well */
 837                         if (__node_allowed(ctx, node)) {
 838                                 __spu_del_from_rq(ctx);
 839                                 goto found;
 840                         }
 841                 }
 842                 best++;
 843         }
 844         ctx = NULL;
 845  found:
 846         spin_unlock(&spu_prio->runq_lock);
 847         return ctx;
 848 }
 849 
 850 static int __spu_deactivate(struct spu_context *ctx, int force, int max_prio)
 851 {
 852         struct spu *spu = ctx->spu;
 853         struct spu_context *new = NULL;
 854 
 855         if (spu) {
 856                 new = grab_runnable_context(max_prio, spu->node);
 857                 if (new || force) {
 858                         spu_unschedule(spu, ctx, new == NULL);
 859                         if (new) {
 860                                 if (new->flags & SPU_CREATE_NOSCHED)
 861                                         wake_up(&new->stop_wq);
 862                                 else {
 863                                         spu_release(ctx);
 864                                         spu_schedule(spu, new);
 865                                         /* this one can't easily be made
 866                                            interruptible */
 867                                         mutex_lock(&ctx->state_mutex);
 868                                 }
 869                         }
 870                 }
 871         }
 872 
 873         return new != NULL;
 874 }
 875 
 876 /**
 877  * spu_deactivate - unbind a context from it's physical spu
 878  * @ctx:        spu context to unbind
 879  *
 880  * Unbind @ctx from the physical spu it is running on and schedule
 881  * the highest priority context to run on the freed physical spu.
 882  */
 883 void spu_deactivate(struct spu_context *ctx)
 884 {
 885         spu_context_nospu_trace(spu_deactivate__enter, ctx);
 886         __spu_deactivate(ctx, 1, MAX_PRIO);
 887 }
 888 
 889 /**
 890  * spu_yield -  yield a physical spu if others are waiting
 891  * @ctx:        spu context to yield
 892  *
 893  * Check if there is a higher priority context waiting and if yes
 894  * unbind @ctx from the physical spu and schedule the highest
 895  * priority context to run on the freed physical spu instead.
 896  */
 897 void spu_yield(struct spu_context *ctx)
 898 {
 899         spu_context_nospu_trace(spu_yield__enter, ctx);
 900         if (!(ctx->flags & SPU_CREATE_NOSCHED)) {
 901                 mutex_lock(&ctx->state_mutex);
 902                 __spu_deactivate(ctx, 0, MAX_PRIO);
 903                 mutex_unlock(&ctx->state_mutex);
 904         }
 905 }
 906 
 907 static noinline void spusched_tick(struct spu_context *ctx)
 908 {
 909         struct spu_context *new = NULL;
 910         struct spu *spu = NULL;
 911 
 912         if (spu_acquire(ctx))
 913                 BUG();  /* a kernel thread never has signals pending */
 914 
 915         if (ctx->state != SPU_STATE_RUNNABLE)
 916                 goto out;
 917         if (ctx->flags & SPU_CREATE_NOSCHED)
 918                 goto out;
 919         if (ctx->policy == SCHED_FIFO)
 920                 goto out;
 921 
 922         if (--ctx->time_slice && test_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags))
 923                 goto out;
 924 
 925         spu = ctx->spu;
 926 
 927         spu_context_trace(spusched_tick__preempt, ctx, spu);
 928 
 929         new = grab_runnable_context(ctx->prio + 1, spu->node);
 930         if (new) {
 931                 spu_unschedule(spu, ctx, 0);
 932                 if (test_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags))
 933                         spu_add_to_rq(ctx);
 934         } else {
 935                 spu_context_nospu_trace(spusched_tick__newslice, ctx);
 936                 if (!ctx->time_slice)
 937                         ctx->time_slice++;
 938         }
 939 out:
 940         spu_release(ctx);
 941 
 942         if (new)
 943                 spu_schedule(spu, new);
 944 }
 945 
 946 /**
 947  * count_active_contexts - count nr of active tasks
 948  *
 949  * Return the number of tasks currently running or waiting to run.
 950  *
 951  * Note that we don't take runq_lock / list_mutex here.  Reading
 952  * a single 32bit value is atomic on powerpc, and we don't care
 953  * about memory ordering issues here.
 954  */
 955 static unsigned long count_active_contexts(void)
 956 {
 957         int nr_active = 0, node;
 958 
 959         for (node = 0; node < MAX_NUMNODES; node++)
 960                 nr_active += cbe_spu_info[node].nr_active;
 961         nr_active += spu_prio->nr_waiting;
 962 
 963         return nr_active;
 964 }
 965 
 966 /**
 967  * spu_calc_load - update the avenrun load estimates.
 968  *
 969  * No locking against reading these values from userspace, as for
 970  * the CPU loadavg code.
 971  */
 972 static void spu_calc_load(void)
 973 {
 974         unsigned long active_tasks; /* fixed-point */
 975 
 976         active_tasks = count_active_contexts() * FIXED_1;
 977         spu_avenrun[0] = calc_load(spu_avenrun[0], EXP_1, active_tasks);
 978         spu_avenrun[1] = calc_load(spu_avenrun[1], EXP_5, active_tasks);
 979         spu_avenrun[2] = calc_load(spu_avenrun[2], EXP_15, active_tasks);
 980 }
 981 
 982 static void spusched_wake(struct timer_list *unused)
 983 {
 984         mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
 985         wake_up_process(spusched_task);
 986 }
 987 
 988 static void spuloadavg_wake(struct timer_list *unused)
 989 {
 990         mod_timer(&spuloadavg_timer, jiffies + LOAD_FREQ);
 991         spu_calc_load();
 992 }
 993 
 994 static int spusched_thread(void *unused)
 995 {
 996         struct spu *spu;
 997         int node;
 998 
 999         while (!kthread_should_stop()) {
1000                 set_current_state(TASK_INTERRUPTIBLE);
1001                 schedule();
1002                 for (node = 0; node < MAX_NUMNODES; node++) {
1003                         struct mutex *mtx = &cbe_spu_info[node].list_mutex;
1004 
1005                         mutex_lock(mtx);
1006                         list_for_each_entry(spu, &cbe_spu_info[node].spus,
1007                                         cbe_list) {
1008                                 struct spu_context *ctx = spu->ctx;
1009 
1010                                 if (ctx) {
1011                                         get_spu_context(ctx);
1012                                         mutex_unlock(mtx);
1013                                         spusched_tick(ctx);
1014                                         mutex_lock(mtx);
1015                                         put_spu_context(ctx);
1016                                 }
1017                         }
1018                         mutex_unlock(mtx);
1019                 }
1020         }
1021 
1022         return 0;
1023 }
1024 
1025 void spuctx_switch_state(struct spu_context *ctx,
1026                 enum spu_utilization_state new_state)
1027 {
1028         unsigned long long curtime;
1029         signed long long delta;
1030         struct spu *spu;
1031         enum spu_utilization_state old_state;
1032         int node;
1033 
1034         curtime = ktime_get_ns();
1035         delta = curtime - ctx->stats.tstamp;
1036 
1037         WARN_ON(!mutex_is_locked(&ctx->state_mutex));
1038         WARN_ON(delta < 0);
1039 
1040         spu = ctx->spu;
1041         old_state = ctx->stats.util_state;
1042         ctx->stats.util_state = new_state;
1043         ctx->stats.tstamp = curtime;
1044 
1045         /*
1046          * Update the physical SPU utilization statistics.
1047          */
1048         if (spu) {
1049                 ctx->stats.times[old_state] += delta;
1050                 spu->stats.times[old_state] += delta;
1051                 spu->stats.util_state = new_state;
1052                 spu->stats.tstamp = curtime;
1053                 node = spu->node;
1054                 if (old_state == SPU_UTIL_USER)
1055                         atomic_dec(&cbe_spu_info[node].busy_spus);
1056                 if (new_state == SPU_UTIL_USER)
1057                         atomic_inc(&cbe_spu_info[node].busy_spus);
1058         }
1059 }
1060 
1061 static int show_spu_loadavg(struct seq_file *s, void *private)
1062 {
1063         int a, b, c;
1064 
1065         a = spu_avenrun[0] + (FIXED_1/200);
1066         b = spu_avenrun[1] + (FIXED_1/200);
1067         c = spu_avenrun[2] + (FIXED_1/200);
1068 
1069         /*
1070          * Note that last_pid doesn't really make much sense for the
1071          * SPU loadavg (it even seems very odd on the CPU side...),
1072          * but we include it here to have a 100% compatible interface.
1073          */
1074         seq_printf(s, "%d.%02d %d.%02d %d.%02d %ld/%d %d\n",
1075                 LOAD_INT(a), LOAD_FRAC(a),
1076                 LOAD_INT(b), LOAD_FRAC(b),
1077                 LOAD_INT(c), LOAD_FRAC(c),
1078                 count_active_contexts(),
1079                 atomic_read(&nr_spu_contexts),
1080                 idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
1081         return 0;
1082 };
1083 
1084 int __init spu_sched_init(void)
1085 {
1086         struct proc_dir_entry *entry;
1087         int err = -ENOMEM, i;
1088 
1089         spu_prio = kzalloc(sizeof(struct spu_prio_array), GFP_KERNEL);
1090         if (!spu_prio)
1091                 goto out;
1092 
1093         for (i = 0; i < MAX_PRIO; i++) {
1094                 INIT_LIST_HEAD(&spu_prio->runq[i]);
1095                 __clear_bit(i, spu_prio->bitmap);
1096         }
1097         spin_lock_init(&spu_prio->runq_lock);
1098 
1099         timer_setup(&spusched_timer, spusched_wake, 0);
1100         timer_setup(&spuloadavg_timer, spuloadavg_wake, 0);
1101 
1102         spusched_task = kthread_run(spusched_thread, NULL, "spusched");
1103         if (IS_ERR(spusched_task)) {
1104                 err = PTR_ERR(spusched_task);
1105                 goto out_free_spu_prio;
1106         }
1107 
1108         mod_timer(&spuloadavg_timer, 0);
1109 
1110         entry = proc_create_single("spu_loadavg", 0, NULL, show_spu_loadavg);
1111         if (!entry)
1112                 goto out_stop_kthread;
1113 
1114         pr_debug("spusched: tick: %d, min ticks: %d, default ticks: %d\n",
1115                         SPUSCHED_TICK, MIN_SPU_TIMESLICE, DEF_SPU_TIMESLICE);
1116         return 0;
1117 
1118  out_stop_kthread:
1119         kthread_stop(spusched_task);
1120  out_free_spu_prio:
1121         kfree(spu_prio);
1122  out:
1123         return err;
1124 }
1125 
1126 void spu_sched_exit(void)
1127 {
1128         struct spu *spu;
1129         int node;
1130 
1131         remove_proc_entry("spu_loadavg", NULL);
1132 
1133         del_timer_sync(&spusched_timer);
1134         del_timer_sync(&spuloadavg_timer);
1135         kthread_stop(spusched_task);
1136 
1137         for (node = 0; node < MAX_NUMNODES; node++) {
1138                 mutex_lock(&cbe_spu_info[node].list_mutex);
1139                 list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list)
1140                         if (spu->alloc_state != SPU_FREE)
1141                                 spu->alloc_state = SPU_FREE;
1142                 mutex_unlock(&cbe_spu_info[node].list_mutex);
1143         }
1144         kfree(spu_prio);
1145 }