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   1 /* sched.c - SPU scheduler.
   2  *
   3  * Copyright (C) IBM 2005
   4  * Author: Mark Nutter <mnutter@us.ibm.com>
   5  *
   6  * 2006-03-31   NUMA domains added.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21  */
  22
  23 #undef DEBUG
  24
  25 #include <linux/module.h>
  26 #include <linux/errno.h>
  27 #include <linux/sched.h>
  28 #include <linux/kernel.h>
  29 #include <linux/mm.h>
  30 #include <linux/completion.h>
  31 #include <linux/vmalloc.h>
  32 #include <linux/smp.h>
  33 #include <linux/smp_lock.h>
  34 #include <linux/stddef.h>
  35 #include <linux/unistd.h>
  36 #include <linux/numa.h>
  37 #include <linux/mutex.h>
  38 #include <linux/notifier.h>
  39
  40 #include <asm/io.h>
  41 #include <asm/mmu_context.h>
  42 #include <asm/spu.h>
  43 #include <asm/spu_csa.h>
  44 #include <asm/spu_priv1.h>
  45 #include "spufs.h"
  46
  47 #define SPU_MIN_TIMESLICE       (100 * HZ / 1000)
  48
  49 #define SPU_BITMAP_SIZE (((MAX_PRIO+BITS_PER_LONG)/BITS_PER_LONG)+1)
  50 struct spu_prio_array {
  51         unsigned long bitmap[SPU_BITMAP_SIZE];
  52         wait_queue_head_t waitq[MAX_PRIO];
  53         struct list_head active_list[MAX_NUMNODES];
  54         struct mutex active_mutex[MAX_NUMNODES];
  55 };
  56
  57 static struct spu_prio_array *spu_prio;
  58
  59 static inline int node_allowed(int node)
  60 {
  61         cpumask_t mask;
  62
  63         if (!nr_cpus_node(node))
  64                 return 0;
  65         mask = node_to_cpumask(node);
  66         if (!cpus_intersects(mask, current->cpus_allowed))
  67                 return 0;
  68         return 1;
  69 }
  70
  71 static inline void mm_needs_global_tlbie(struct mm_struct *mm)
  72 {
  73         int nr = (NR_CPUS > 1) ? NR_CPUS : NR_CPUS + 1;
  74
  75         /* Global TLBIE broadcast required with SPEs. */
  76         __cpus_setall(&mm->cpu_vm_mask, nr);
  77 }
  78
  79 static BLOCKING_NOTIFIER_HEAD(spu_switch_notifier);
  80
  81 static void spu_switch_notify(struct spu *spu, struct spu_context *ctx)
  82 {
  83         blocking_notifier_call_chain(&spu_switch_notifier,
  84                             ctx ? ctx->object_id : 0, spu);
  85 }
  86
  87 int spu_switch_event_register(struct notifier_block * n)
  88 {
  89         return blocking_notifier_chain_register(&spu_switch_notifier, n);
  90 }
  91
  92 int spu_switch_event_unregister(struct notifier_block * n)
  93 {
  94         return blocking_notifier_chain_unregister(&spu_switch_notifier, n);
  95 }
  96
  97
  98 static inline void bind_context(struct spu *spu, struct spu_context *ctx)
  99 {
 100         pr_debug("%s: pid=%d SPU=%d NODE=%d\n", __FUNCTION__, current->pid,
 101                  spu->number, spu->node);
 102         spu->ctx = ctx;
 103         spu->flags = 0;
 104         ctx->spu = spu;
 105         ctx->ops = &spu_hw_ops;
 106         spu->pid = current->pid;
 107         spu->prio = current->prio;
 108         spu->mm = ctx->owner;
 109         mm_needs_global_tlbie(spu->mm);
 110         spu->ibox_callback = spufs_ibox_callback;
 111         spu->wbox_callback = spufs_wbox_callback;
 112         spu->stop_callback = spufs_stop_callback;
 113         spu->mfc_callback = spufs_mfc_callback;
 114         spu->dma_callback = spufs_dma_callback;
 115         mb();
 116         spu_unmap_mappings(ctx);
 117         spu_restore(&ctx->csa, spu);
 118         spu->timestamp = jiffies;
 119         spu_cpu_affinity_set(spu, raw_smp_processor_id());
 120         spu_switch_notify(spu, ctx);
 121 }
 122
 123 static inline void unbind_context(struct spu *spu, struct spu_context *ctx)
 124 {
 125         pr_debug("%s: unbind pid=%d SPU=%d NODE=%d\n", __FUNCTION__,
 126                  spu->pid, spu->number, spu->node);
 127         spu_switch_notify(spu, NULL);
 128         spu_unmap_mappings(ctx);
 129         spu_save(&ctx->csa, spu);
 130         spu->timestamp = jiffies;
 131         ctx->state = SPU_STATE_SAVED;
 132         spu->ibox_callback = NULL;
 133         spu->wbox_callback = NULL;
 134         spu->stop_callback = NULL;
 135         spu->mfc_callback = NULL;
 136         spu->dma_callback = NULL;
 137         spu->mm = NULL;
 138         spu->pid = 0;
 139         spu->prio = MAX_PRIO;
 140         ctx->ops = &spu_backing_ops;
 141         ctx->spu = NULL;
 142         spu->flags = 0;
 143         spu->ctx = NULL;
 144 }
 145
 146 static inline void spu_add_wq(wait_queue_head_t * wq, wait_queue_t * wait,
 147                               int prio)
 148 {
 149         prepare_to_wait_exclusive(wq, wait, TASK_INTERRUPTIBLE);
 150         set_bit(prio, spu_prio->bitmap);
 151 }
 152
 153 static inline void spu_del_wq(wait_queue_head_t * wq, wait_queue_t * wait,
 154                               int prio)
 155 {
 156         u64 flags;
 157
 158         __set_current_state(TASK_RUNNING);
 159
 160         spin_lock_irqsave(&wq->lock, flags);
 161
 162         remove_wait_queue_locked(wq, wait);
 163         if (list_empty(&wq->task_list))
 164                 clear_bit(prio, spu_prio->bitmap);
 165
 166         spin_unlock_irqrestore(&wq->lock, flags);
 167 }
 168
 169 static void spu_prio_wait(struct spu_context *ctx, u64 flags)
 170 {
 171         int prio = current->prio;
 172         wait_queue_head_t *wq = &spu_prio->waitq[prio];
 173         DEFINE_WAIT(wait);
 174
 175         if (ctx->spu)
 176                 return;
 177
 178         spu_add_wq(wq, &wait, prio);
 179
 180         if (!signal_pending(current)) {
 181                 up_write(&ctx->state_sema);
 182                 pr_debug("%s: pid=%d prio=%d\n", __FUNCTION__,
 183                          current->pid, current->prio);
 184                 schedule();
 185                 down_write(&ctx->state_sema);
 186         }
 187
 188         spu_del_wq(wq, &wait, prio);
 189 }
 190
 191 static void spu_prio_wakeup(void)
 192 {
 193         int best = sched_find_first_bit(spu_prio->bitmap);
 194         if (best < MAX_PRIO) {
 195                 wait_queue_head_t *wq = &spu_prio->waitq[best];
 196                 wake_up_interruptible_nr(wq, 1);
 197         }
 198 }
 199
 200 static int get_active_spu(struct spu *spu)
 201 {
 202         int node = spu->node;
 203         struct spu *tmp;
 204         int rc = 0;
 205
 206         mutex_lock(&spu_prio->active_mutex[node]);
 207         list_for_each_entry(tmp, &spu_prio->active_list[node], list) {
 208                 if (tmp == spu) {
 209                         list_del_init(&spu->list);
 210                         rc = 1;
 211                         break;
 212                 }
 213         }
 214         mutex_unlock(&spu_prio->active_mutex[node]);
 215         return rc;
 216 }
 217
 218 static void put_active_spu(struct spu *spu)
 219 {
 220         int node = spu->node;
 221
 222         mutex_lock(&spu_prio->active_mutex[node]);
 223         list_add_tail(&spu->list, &spu_prio->active_list[node]);
 224         mutex_unlock(&spu_prio->active_mutex[node]);
 225 }
 226
 227 static struct spu *spu_get_idle(struct spu_context *ctx, u64 flags)
 228 {
 229         struct spu *spu = NULL;
 230         int node = cpu_to_node(raw_smp_processor_id());
 231         int n;
 232
 233         for (n = 0; n < MAX_NUMNODES; n++, node++) {
 234                 node = (node < MAX_NUMNODES) ? node : 0;
 235                 if (!node_allowed(node))
 236                         continue;
 237                 spu = spu_alloc_node(node);
 238                 if (spu)
 239                         break;
 240         }
 241         return spu;
 242 }
 243
 244 static inline struct spu *spu_get(struct spu_context *ctx, u64 flags)
 245 {
 246         /* Future: spu_get_idle() if possible,
 247          * otherwise try to preempt an active
 248          * context.
 249          */
 250         return spu_get_idle(ctx, flags);
 251 }
 252
 253 /* The three externally callable interfaces
 254  * for the scheduler begin here.
 255  *
 256  *      spu_activate    - bind a context to SPU, waiting as needed.
 257  *      spu_deactivate  - unbind a context from its SPU.
 258  *      spu_yield       - yield an SPU if others are waiting.
 259  */
 260
 261 int spu_activate(struct spu_context *ctx, u64 flags)
 262 {
 263         struct spu *spu;
 264         int ret = 0;
 265
 266         for (;;) {
 267                 if (ctx->spu)
 268                         return 0;
 269                 spu = spu_get(ctx, flags);
 270                 if (spu != NULL) {
 271                         if (ctx->spu != NULL) {
 272                                 spu_free(spu);
 273                                 spu_prio_wakeup();
 274                                 break;
 275                         }
 276                         bind_context(spu, ctx);
 277                         put_active_spu(spu);
 278                         break;
 279                 }
 280                 spu_prio_wait(ctx, flags);
 281                 if (signal_pending(current)) {
 282                         ret = -ERESTARTSYS;
 283                         spu_prio_wakeup();
 284                         break;
 285                 }
 286         }
 287         return ret;
 288 }
 289
 290 void spu_deactivate(struct spu_context *ctx)
 291 {
 292         struct spu *spu;
 293         int needs_idle;
 294
 295         spu = ctx->spu;
 296         if (!spu)
 297                 return;
 298         needs_idle = get_active_spu(spu);
 299         unbind_context(spu, ctx);
 300         if (needs_idle) {
 301                 spu_free(spu);
 302                 spu_prio_wakeup();
 303         }
 304 }
 305
 306 void spu_yield(struct spu_context *ctx)
 307 {
 308         struct spu *spu;
 309         int need_yield = 0;
 310
 311         if (down_write_trylock(&ctx->state_sema)) {
 312                 if ((spu = ctx->spu) != NULL) {
 313                         int best = sched_find_first_bit(spu_prio->bitmap);
 314                         if (best < MAX_PRIO) {
 315                                 pr_debug("%s: yielding SPU %d NODE %d\n",
 316                                          __FUNCTION__, spu->number, spu->node);
 317                                 spu_deactivate(ctx);
 318                                 ctx->state = SPU_STATE_SAVED;
 319                                 need_yield = 1;
 320                         } else {
 321                                 spu->prio = MAX_PRIO;
 322                         }
 323                 }
 324                 up_write(&ctx->state_sema);
 325         }
 326         if (unlikely(need_yield))
 327                 yield();
 328 }
 329
 330 int __init spu_sched_init(void)
 331 {
 332         int i;
 333
 334         spu_prio = kzalloc(sizeof(struct spu_prio_array), GFP_KERNEL);
 335         if (!spu_prio) {
 336                 printk(KERN_WARNING "%s: Unable to allocate priority queue.\n",
 337                        __FUNCTION__);
 338                 return 1;
 339         }
 340         for (i = 0; i < MAX_PRIO; i++) {
 341                 init_waitqueue_head(&spu_prio->waitq[i]);
 342                 __clear_bit(i, spu_prio->bitmap);
 343         }
 344         __set_bit(MAX_PRIO, spu_prio->bitmap);
 345         for (i = 0; i < MAX_NUMNODES; i++) {
 346                 mutex_init(&spu_prio->active_mutex[i]);
 347                 INIT_LIST_HEAD(&spu_prio->active_list[i]);
 348         }
 349         return 0;
 350 }
 351
 352 void __exit spu_sched_exit(void)
 353 {
 354         struct spu *spu, *tmp;
 355         int node;
 356
 357         for (node = 0; node < MAX_NUMNODES; node++) {
 358                 mutex_lock(&spu_prio->active_mutex[node]);
 359                 list_for_each_entry_safe(spu, tmp, &spu_prio->active_list[node],
 360                                          list) {
 361                         list_del_init(&spu->list);
 362                         spu_free(spu);
 363                 }
 364                 mutex_unlock(&spu_prio->active_mutex[node]);
 365         }
 366         kfree(spu_prio);
 367 }