mm/vmstat.c

   1 /*
   2  *  linux/mm/vmstat.c
   3  *
   4  *  Manages VM statistics
   5  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   6  *
   7  *  zoned VM statistics
   8  *  Copyright (C) 2006 Silicon Graphics, Inc.,
   9  *              Christoph Lameter <christoph@lameter.com>
  10  */
  11 #include <linux/fs.h>
  12 #include <linux/mm.h>
  13 #include <linux/err.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/cpu.h>
  17 #include <linux/vmstat.h>
  18 #include <linux/sched.h>
  19 #include <linux/math64.h>
  20 #include <linux/writeback.h>
  21 #include <linux/compaction.h>
  22
  23 #ifdef CONFIG_VM_EVENT_COUNTERS
  24 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
  25 EXPORT_PER_CPU_SYMBOL(vm_event_states);
  26
  27 static void sum_vm_events(unsigned long *ret)
  28 {
  29         int cpu;
  30         int i;
  31
  32         memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
  33
  34         for_each_online_cpu(cpu) {
  35                 struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
  36
  37                 for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
  38                         ret[i] += this->event[i];
  39         }
  40 }
  41
  42 /*
  43  * Accumulate the vm event counters across all CPUs.
  44  * The result is unavoidably approximate - it can change
  45  * during and after execution of this function.
  46 */
  47 void all_vm_events(unsigned long *ret)
  48 {
  49         get_online_cpus();
  50         sum_vm_events(ret);
  51         put_online_cpus();
  52 }
  53 EXPORT_SYMBOL_GPL(all_vm_events);
  54
  55 #ifdef CONFIG_HOTPLUG
  56 /*
  57  * Fold the foreign cpu events into our own.
  58  *
  59  * This is adding to the events on one processor
  60  * but keeps the global counts constant.
  61  */
  62 void vm_events_fold_cpu(int cpu)
  63 {
  64         struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
  65         int i;
  66
  67         for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
  68                 count_vm_events(i, fold_state->event[i]);
  69                 fold_state->event[i] = 0;
  70         }
  71 }
  72 #endif /* CONFIG_HOTPLUG */
  73
  74 #endif /* CONFIG_VM_EVENT_COUNTERS */
  75
  76 /*
  77  * Manage combined zone based / global counters
  78  *
  79  * vm_stat contains the global counters
  80  */
  81 atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
  82 EXPORT_SYMBOL(vm_stat);
  83
  84 #ifdef CONFIG_SMP
  85
  86 static int calculate_pressure_threshold(struct zone *zone)
  87 {
  88         int threshold;
  89         int watermark_distance;
  90
  91         /*
  92          * As vmstats are not up to date, there is drift between the estimated
  93          * and real values. For high thresholds and a high number of CPUs, it
  94          * is possible for the min watermark to be breached while the estimated
  95          * value looks fine. The pressure threshold is a reduced value such
  96          * that even the maximum amount of drift will not accidentally breach
  97          * the min watermark
  98          */
  99         watermark_distance = low_wmark_pages(zone) - min_wmark_pages(zone);
 100         threshold = max(1, (int)(watermark_distance / num_online_cpus()));
 101
 102         /*
 103          * Maximum threshold is 125
 104          */
 105         threshold = min(125, threshold);
 106
 107         return threshold;
 108 }
 109
 110 static int calculate_threshold(struct zone *zone)
 111 {
 112         int threshold;
 113         int mem;        /* memory in 128 MB units */
 114
 115         /*
 116          * The threshold scales with the number of processors and the amount
 117          * of memory per zone. More memory means that we can defer updates for
 118          * longer, more processors could lead to more contention.
 119          * fls() is used to have a cheap way of logarithmic scaling.
 120          *
 121          * Some sample thresholds:
 122          *
 123          * Threshold    Processors      (fls)   Zonesize        fls(mem+1)
 124          * ------------------------------------------------------------------
 125          * 8            1               1       0.9-1 GB        4
 126          * 16           2               2       0.9-1 GB        4
 127          * 20           2               2       1-2 GB          5
 128          * 24           2               2       2-4 GB          6
 129          * 28           2               2       4-8 GB          7
 130          * 32           2               2       8-16 GB         8
 131          * 4            2               2       <128M           1
 132          * 30           4               3       2-4 GB          5
 133          * 48           4               3       8-16 GB         8
 134          * 32           8               4       1-2 GB          4
 135          * 32           8               4       0.9-1GB         4
 136          * 10           16              5       <128M           1
 137          * 40           16              5       900M            4
 138          * 70           64              7       2-4 GB          5
 139          * 84           64              7       4-8 GB          6
 140          * 108          512             9       4-8 GB          6
 141          * 125          1024            10      8-16 GB         8
 142          * 125          1024            10      16-32 GB        9
 143          */
 144
 145         mem = zone->present_pages >> (27 - PAGE_SHIFT);
 146
 147         threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
 148
 149         /*
 150          * Maximum threshold is 125
 151          */
 152         threshold = min(125, threshold);
 153
 154         return threshold;
 155 }
 156
 157 /*
 158  * Refresh the thresholds for each zone.
 159  */
 160 static void refresh_zone_stat_thresholds(void)
 161 {
 162         struct zone *zone;
 163         int cpu;
 164         int threshold;
 165
 166         for_each_populated_zone(zone) {
 167                 unsigned long max_drift, tolerate_drift;
 168
 169                 threshold = calculate_threshold(zone);
 170
 171                 for_each_online_cpu(cpu)
 172                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 173                                                         = threshold;
 174
 175                 /*
 176                  * Only set percpu_drift_mark if there is a danger that
 177                  * NR_FREE_PAGES reports the low watermark is ok when in fact
 178                  * the min watermark could be breached by an allocation
 179                  */
 180                 tolerate_drift = low_wmark_pages(zone) - min_wmark_pages(zone);
 181                 max_drift = num_online_cpus() * threshold;
 182                 if (max_drift > tolerate_drift)
 183                         zone->percpu_drift_mark = high_wmark_pages(zone) +
 184                                         max_drift;
 185         }
 186 }
 187
 188 void reduce_pgdat_percpu_threshold(pg_data_t *pgdat)
 189 {
 190         struct zone *zone;
 191         int cpu;
 192         int threshold;
 193         int i;
 194
 195         get_online_cpus();
 196         for (i = 0; i < pgdat->nr_zones; i++) {
 197                 zone = &pgdat->node_zones[i];
 198                 if (!zone->percpu_drift_mark)
 199                         continue;
 200
 201                 threshold = calculate_pressure_threshold(zone);
 202                 for_each_online_cpu(cpu)
 203                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 204                                                         = threshold;
 205         }
 206         put_online_cpus();
 207 }
 208
 209 void restore_pgdat_percpu_threshold(pg_data_t *pgdat)
 210 {
 211         struct zone *zone;
 212         int cpu;
 213         int threshold;
 214         int i;
 215
 216         get_online_cpus();
 217         for (i = 0; i < pgdat->nr_zones; i++) {
 218                 zone = &pgdat->node_zones[i];
 219                 if (!zone->percpu_drift_mark)
 220                         continue;
 221
 222                 threshold = calculate_threshold(zone);
 223                 for_each_online_cpu(cpu)
 224                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 225                                                         = threshold;
 226         }
 227         put_online_cpus();
 228 }
 229
 230 /*
 231  * For use when we know that interrupts are disabled.
 232  */
 233 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 234                                 int delta)
 235 {
 236         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 237         s8 __percpu *p = pcp->vm_stat_diff + item;
 238         long x;
 239         long t;
 240
 241         x = delta + __this_cpu_read(*p);
 242
 243         t = __this_cpu_read(pcp->stat_threshold);
 244
 245         if (unlikely(x > t || x < -t)) {
 246                 zone_page_state_add(x, zone, item);
 247                 x = 0;
 248         }
 249         __this_cpu_write(*p, x);
 250 }
 251 EXPORT_SYMBOL(__mod_zone_page_state);
 252
 253 /*
 254  * Optimized increment and decrement functions.
 255  *
 256  * These are only for a single page and therefore can take a struct page *
 257  * argument instead of struct zone *. This allows the inclusion of the code
 258  * generated for page_zone(page) into the optimized functions.
 259  *
 260  * No overflow check is necessary and therefore the differential can be
 261  * incremented or decremented in place which may allow the compilers to
 262  * generate better code.
 263  * The increment or decrement is known and therefore one boundary check can
 264  * be omitted.
 265  *
 266  * NOTE: These functions are very performance sensitive. Change only
 267  * with care.
 268  *
 269  * Some processors have inc/dec instructions that are atomic vs an interrupt.
 270  * However, the code must first determine the differential location in a zone
 271  * based on the processor number and then inc/dec the counter. There is no
 272  * guarantee without disabling preemption that the processor will not change
 273  * in between and therefore the atomicity vs. interrupt cannot be exploited
 274  * in a useful way here.
 275  */
 276 void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 277 {
 278         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 279         s8 __percpu *p = pcp->vm_stat_diff + item;
 280         s8 v, t;
 281
 282         v = __this_cpu_inc_return(*p);
 283         t = __this_cpu_read(pcp->stat_threshold);
 284         if (unlikely(v > t)) {
 285                 s8 overstep = t >> 1;
 286
 287                 zone_page_state_add(v + overstep, zone, item);
 288                 __this_cpu_write(*p, -overstep);
 289         }
 290 }
 291
 292 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
 293 {
 294         __inc_zone_state(page_zone(page), item);
 295 }
 296 EXPORT_SYMBOL(__inc_zone_page_state);
 297
 298 void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 299 {
 300         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 301         s8 __percpu *p = pcp->vm_stat_diff + item;
 302         s8 v, t;
 303
 304         v = __this_cpu_dec_return(*p);
 305         t = __this_cpu_read(pcp->stat_threshold);
 306         if (unlikely(v < - t)) {
 307                 s8 overstep = t >> 1;
 308
 309                 zone_page_state_add(v - overstep, zone, item);
 310                 __this_cpu_write(*p, overstep);
 311         }
 312 }
 313
 314 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
 315 {
 316         __dec_zone_state(page_zone(page), item);
 317 }
 318 EXPORT_SYMBOL(__dec_zone_page_state);
 319
 320 #ifdef CONFIG_CMPXCHG_LOCAL
 321 /*
 322  * If we have cmpxchg_local support then we do not need to incur the overhead
 323  * that comes with local_irq_save/restore if we use this_cpu_cmpxchg.
 324  *
 325  * mod_state() modifies the zone counter state through atomic per cpu
 326  * operations.
 327  *
 328  * Overstep mode specifies how overstep should handled:
 329  *     0       No overstepping
 330  *     1       Overstepping half of threshold
 331  *     -1      Overstepping minus half of threshold
 332 */
 333 static inline void mod_state(struct zone *zone,
 334        enum zone_stat_item item, int delta, int overstep_mode)
 335 {
 336         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 337         s8 __percpu *p = pcp->vm_stat_diff + item;
 338         long o, n, t, z;
 339
 340         do {
 341                 z = 0;  /* overflow to zone counters */
 342
 343                 /*
 344                  * The fetching of the stat_threshold is racy. We may apply
 345                  * a counter threshold to the wrong the cpu if we get
 346                  * rescheduled while executing here. However, the following
 347                  * will apply the threshold again and therefore bring the
 348                  * counter under the threshold.
 349                  */
 350                 t = this_cpu_read(pcp->stat_threshold);
 351
 352                 o = this_cpu_read(*p);
 353                 n = delta + o;
 354
 355                 if (n > t || n < -t) {
 356                         int os = overstep_mode * (t >> 1) ;
 357
 358                         /* Overflow must be added to zone counters */
 359                         z = n + os;
 360                         n = -os;
 361                 }
 362         } while (this_cpu_cmpxchg(*p, o, n) != o);
 363
 364         if (z)
 365                 zone_page_state_add(z, zone, item);
 366 }
 367
 368 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 369                                         int delta)
 370 {
 371         mod_state(zone, item, delta, 0);
 372 }
 373 EXPORT_SYMBOL(mod_zone_page_state);
 374
 375 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
 376 {
 377         mod_state(zone, item, 1, 1);
 378 }
 379
 380 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 381 {
 382         mod_state(page_zone(page), item, 1, 1);
 383 }
 384 EXPORT_SYMBOL(inc_zone_page_state);
 385
 386 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 387 {
 388         mod_state(page_zone(page), item, -1, -1);
 389 }
 390 EXPORT_SYMBOL(dec_zone_page_state);
 391 #else
 392 /*
 393  * Use interrupt disable to serialize counter updates
 394  */
 395 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 396                                         int delta)
 397 {
 398         unsigned long flags;
 399
 400         local_irq_save(flags);
 401         __mod_zone_page_state(zone, item, delta);
 402         local_irq_restore(flags);
 403 }
 404 EXPORT_SYMBOL(mod_zone_page_state);
 405
 406 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
 407 {
 408         unsigned long flags;
 409
 410         local_irq_save(flags);
 411         __inc_zone_state(zone, item);
 412         local_irq_restore(flags);
 413 }
 414
 415 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 416 {
 417         unsigned long flags;
 418         struct zone *zone;
 419
 420         zone = page_zone(page);
 421         local_irq_save(flags);
 422         __inc_zone_state(zone, item);
 423         local_irq_restore(flags);
 424 }
 425 EXPORT_SYMBOL(inc_zone_page_state);
 426
 427 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 428 {
 429         unsigned long flags;
 430
 431         local_irq_save(flags);
 432         __dec_zone_page_state(page, item);
 433         local_irq_restore(flags);
 434 }
 435 EXPORT_SYMBOL(dec_zone_page_state);
 436 #endif
 437
 438 /*
 439  * Update the zone counters for one cpu.
 440  *
 441  * The cpu specified must be either the current cpu or a processor that
 442  * is not online. If it is the current cpu then the execution thread must
 443  * be pinned to the current cpu.
 444  *
 445  * Note that refresh_cpu_vm_stats strives to only access
 446  * node local memory. The per cpu pagesets on remote zones are placed
 447  * in the memory local to the processor using that pageset. So the
 448  * loop over all zones will access a series of cachelines local to
 449  * the processor.
 450  *
 451  * The call to zone_page_state_add updates the cachelines with the
 452  * statistics in the remote zone struct as well as the global cachelines
 453  * with the global counters. These could cause remote node cache line
 454  * bouncing and will have to be only done when necessary.
 455  */
 456 void refresh_cpu_vm_stats(int cpu)
 457 {
 458         struct zone *zone;
 459         int i;
 460         int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 461
 462         for_each_populated_zone(zone) {
 463                 struct per_cpu_pageset *p;
 464
 465                 p = per_cpu_ptr(zone->pageset, cpu);
 466
 467                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 468                         if (p->vm_stat_diff[i]) {
 469                                 unsigned long flags;
 470                                 int v;
 471
 472                                 local_irq_save(flags);
 473                                 v = p->vm_stat_diff[i];
 474                                 p->vm_stat_diff[i] = 0;
 475                                 local_irq_restore(flags);
 476                                 atomic_long_add(v, &zone->vm_stat[i]);
 477                                 global_diff[i] += v;
 478 #ifdef CONFIG_NUMA
 479                                 /* 3 seconds idle till flush */
 480                                 p->expire = 3;
 481 #endif
 482                         }
 483                 cond_resched();
 484 #ifdef CONFIG_NUMA
 485                 /*
 486                  * Deal with draining the remote pageset of this
 487                  * processor
 488                  *
 489                  * Check if there are pages remaining in this pageset
 490                  * if not then there is nothing to expire.
 491                  */
 492                 if (!p->expire || !p->pcp.count)
 493                         continue;
 494
 495                 /*
 496                  * We never drain zones local to this processor.
 497                  */
 498                 if (zone_to_nid(zone) == numa_node_id()) {
 499                         p->expire = 0;
 500                         continue;
 501                 }
 502
 503                 p->expire--;
 504                 if (p->expire)
 505                         continue;
 506
 507                 if (p->pcp.count)
 508                         drain_zone_pages(zone, &p->pcp);
 509 #endif
 510         }
 511
 512         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 513                 if (global_diff[i])
 514                         atomic_long_add(global_diff[i], &vm_stat[i]);
 515 }
 516
 517 #endif
 518
 519 #ifdef CONFIG_NUMA
 520 /*
 521  * zonelist = the list of zones passed to the allocator
 522  * z        = the zone from which the allocation occurred.
 523  *
 524  * Must be called with interrupts disabled.
 525  */
 526 void zone_statistics(struct zone *preferred_zone, struct zone *z)
 527 {
 528         if (z->zone_pgdat == preferred_zone->zone_pgdat) {
 529                 __inc_zone_state(z, NUMA_HIT);
 530         } else {
 531                 __inc_zone_state(z, NUMA_MISS);
 532                 __inc_zone_state(preferred_zone, NUMA_FOREIGN);
 533         }
 534         if (z->node == numa_node_id())
 535                 __inc_zone_state(z, NUMA_LOCAL);
 536         else
 537                 __inc_zone_state(z, NUMA_OTHER);
 538 }
 539 #endif
 540
 541 #ifdef CONFIG_COMPACTION
 542
 543 struct contig_page_info {
 544         unsigned long free_pages;
 545         unsigned long free_blocks_total;
 546         unsigned long free_blocks_suitable;
 547 };
 548
 549 /*
 550  * Calculate the number of free pages in a zone, how many contiguous
 551  * pages are free and how many are large enough to satisfy an allocation of
 552  * the target size. Note that this function makes no attempt to estimate
 553  * how many suitable free blocks there *might* be if MOVABLE pages were
 554  * migrated. Calculating that is possible, but expensive and can be
 555  * figured out from userspace
 556  */
 557 static void fill_contig_page_info(struct zone *zone,
 558                                 unsigned int suitable_order,
 559                                 struct contig_page_info *info)
 560 {
 561         unsigned int order;
 562
 563         info->free_pages = 0;
 564         info->free_blocks_total = 0;
 565         info->free_blocks_suitable = 0;
 566
 567         for (order = 0; order < MAX_ORDER; order++) {
 568                 unsigned long blocks;
 569
 570                 /* Count number of free blocks */
 571                 blocks = zone->free_area[order].nr_free;
 572                 info->free_blocks_total += blocks;
 573
 574                 /* Count free base pages */
 575                 info->free_pages += blocks << order;
 576
 577                 /* Count the suitable free blocks */
 578                 if (order >= suitable_order)
 579                         info->free_blocks_suitable += blocks <<
 580                                                 (order - suitable_order);
 581         }
 582 }
 583
 584 /*
 585  * A fragmentation index only makes sense if an allocation of a requested
 586  * size would fail. If that is true, the fragmentation index indicates
 587  * whether external fragmentation or a lack of memory was the problem.
 588  * The value can be used to determine if page reclaim or compaction
 589  * should be used
 590  */
 591 static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
 592 {
 593         unsigned long requested = 1UL << order;
 594
 595         if (!info->free_blocks_total)
 596                 return 0;
 597
 598         /* Fragmentation index only makes sense when a request would fail */
 599         if (info->free_blocks_suitable)
 600                 return -1000;
 601
 602         /*
 603          * Index is between 0 and 1 so return within 3 decimal places
 604          *
 605          * 0 => allocation would fail due to lack of memory
 606          * 1 => allocation would fail due to fragmentation
 607          */
 608         return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
 609 }
 610
 611 /* Same as __fragmentation index but allocs contig_page_info on stack */
 612 int fragmentation_index(struct zone *zone, unsigned int order)
 613 {
 614         struct contig_page_info info;
 615
 616         fill_contig_page_info(zone, order, &info);
 617         return __fragmentation_index(order, &info);
 618 }
 619 #endif
 620
 621 #if defined(CONFIG_PROC_FS) || defined(CONFIG_COMPACTION)
 622 #include <linux/proc_fs.h>
 623 #include <linux/seq_file.h>
 624
 625 static char * const migratetype_names[MIGRATE_TYPES] = {
 626         "Unmovable",
 627         "Reclaimable",
 628         "Movable",
 629         "Reserve",
 630         "Isolate",
 631 };
 632
 633 static void *frag_start(struct seq_file *m, loff_t *pos)
 634 {
 635         pg_data_t *pgdat;
 636         loff_t node = *pos;
 637         for (pgdat = first_online_pgdat();
 638              pgdat && node;
 639              pgdat = next_online_pgdat(pgdat))
 640                 --node;
 641
 642         return pgdat;
 643 }
 644
 645 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
 646 {
 647         pg_data_t *pgdat = (pg_data_t *)arg;
 648
 649         (*pos)++;
 650         return next_online_pgdat(pgdat);
 651 }
 652
 653 static void frag_stop(struct seq_file *m, void *arg)
 654 {
 655 }
 656
 657 /* Walk all the zones in a node and print using a callback */
 658 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
 659                 void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
 660 {
 661         struct zone *zone;
 662         struct zone *node_zones = pgdat->node_zones;
 663         unsigned long flags;
 664
 665         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
 666                 if (!populated_zone(zone))
 667                         continue;
 668
 669                 spin_lock_irqsave(&zone->lock, flags);
 670                 print(m, pgdat, zone);
 671                 spin_unlock_irqrestore(&zone->lock, flags);
 672         }
 673 }
 674 #endif
 675
 676 #ifdef CONFIG_PROC_FS
 677 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
 678                                                 struct zone *zone)
 679 {
 680         int order;
 681
 682         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 683         for (order = 0; order < MAX_ORDER; ++order)
 684                 seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
 685         seq_putc(m, '\n');
 686 }
 687
 688 /*
 689  * This walks the free areas for each zone.
 690  */
 691 static int frag_show(struct seq_file *m, void *arg)
 692 {
 693         pg_data_t *pgdat = (pg_data_t *)arg;
 694         walk_zones_in_node(m, pgdat, frag_show_print);
 695         return 0;
 696 }
 697
 698 static void pagetypeinfo_showfree_print(struct seq_file *m,
 699                                         pg_data_t *pgdat, struct zone *zone)
 700 {
 701         int order, mtype;
 702
 703         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
 704                 seq_printf(m, "Node %4d, zone %8s, type %12s ",
 705                                         pgdat->node_id,
 706                                         zone->name,
 707                                         migratetype_names[mtype]);
 708                 for (order = 0; order < MAX_ORDER; ++order) {
 709                         unsigned long freecount = 0;
 710                         struct free_area *area;
 711                         struct list_head *curr;
 712
 713                         area = &(zone->free_area[order]);
 714
 715                         list_for_each(curr, &area->free_list[mtype])
 716                                 freecount++;
 717                         seq_printf(m, "%6lu ", freecount);
 718                 }
 719                 seq_putc(m, '\n');
 720         }
 721 }
 722
 723 /* Print out the free pages at each order for each migatetype */
 724 static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
 725 {
 726         int order;
 727         pg_data_t *pgdat = (pg_data_t *)arg;
 728
 729         /* Print header */
 730         seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
 731         for (order = 0; order < MAX_ORDER; ++order)
 732                 seq_printf(m, "%6d ", order);
 733         seq_putc(m, '\n');
 734
 735         walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
 736
 737         return 0;
 738 }
 739
 740 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
 741                                         pg_data_t *pgdat, struct zone *zone)
 742 {
 743         int mtype;
 744         unsigned long pfn;
 745         unsigned long start_pfn = zone->zone_start_pfn;
 746         unsigned long end_pfn = start_pfn + zone->spanned_pages;
 747         unsigned long count[MIGRATE_TYPES] = { 0, };
 748
 749         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 750                 struct page *page;
 751
 752                 if (!pfn_valid(pfn))
 753                         continue;
 754
 755                 page = pfn_to_page(pfn);
 756
 757                 /* Watch for unexpected holes punched in the memmap */
 758                 if (!memmap_valid_within(pfn, page, zone))
 759                         continue;
 760
 761                 mtype = get_pageblock_migratetype(page);
 762
 763                 if (mtype < MIGRATE_TYPES)
 764                         count[mtype]++;
 765         }
 766
 767         /* Print counts */
 768         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 769         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 770                 seq_printf(m, "%12lu ", count[mtype]);
 771         seq_putc(m, '\n');
 772 }
 773
 774 /* Print out the free pages at each order for each migratetype */
 775 static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 776 {
 777         int mtype;
 778         pg_data_t *pgdat = (pg_data_t *)arg;
 779
 780         seq_printf(m, "\n%-23s", "Number of blocks type ");
 781         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 782                 seq_printf(m, "%12s ", migratetype_names[mtype]);
 783         seq_putc(m, '\n');
 784         walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
 785
 786         return 0;
 787 }
 788
 789 /*
 790  * This prints out statistics in relation to grouping pages by mobility.
 791  * It is expensive to collect so do not constantly read the file.
 792  */
 793 static int pagetypeinfo_show(struct seq_file *m, void *arg)
 794 {
 795         pg_data_t *pgdat = (pg_data_t *)arg;
 796
 797         /* check memoryless node */
 798         if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
 799                 return 0;
 800
 801         seq_printf(m, "Page block order: %d\n", pageblock_order);
 802         seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
 803         seq_putc(m, '\n');
 804         pagetypeinfo_showfree(m, pgdat);
 805         pagetypeinfo_showblockcount(m, pgdat);
 806
 807         return 0;
 808 }
 809
 810 static const struct seq_operations fragmentation_op = {
 811         .start  = frag_start,
 812         .next   = frag_next,
 813         .stop   = frag_stop,
 814         .show   = frag_show,
 815 };
 816
 817 static int fragmentation_open(struct inode *inode, struct file *file)
 818 {
 819         return seq_open(file, &fragmentation_op);
 820 }
 821
 822 static const struct file_operations fragmentation_file_operations = {
 823         .open           = fragmentation_open,
 824         .read           = seq_read,
 825         .llseek         = seq_lseek,
 826         .release        = seq_release,
 827 };
 828
 829 static const struct seq_operations pagetypeinfo_op = {
 830         .start  = frag_start,
 831         .next   = frag_next,
 832         .stop   = frag_stop,
 833         .show   = pagetypeinfo_show,
 834 };
 835
 836 static int pagetypeinfo_open(struct inode *inode, struct file *file)
 837 {
 838         return seq_open(file, &pagetypeinfo_op);
 839 }
 840
 841 static const struct file_operations pagetypeinfo_file_ops = {
 842         .open           = pagetypeinfo_open,
 843         .read           = seq_read,
 844         .llseek         = seq_lseek,
 845         .release        = seq_release,
 846 };
 847
 848 #ifdef CONFIG_ZONE_DMA
 849 #define TEXT_FOR_DMA(xx) xx "_dma",
 850 #else
 851 #define TEXT_FOR_DMA(xx)
 852 #endif
 853
 854 #ifdef CONFIG_ZONE_DMA32
 855 #define TEXT_FOR_DMA32(xx) xx "_dma32",
 856 #else
 857 #define TEXT_FOR_DMA32(xx)
 858 #endif
 859
 860 #ifdef CONFIG_HIGHMEM
 861 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
 862 #else
 863 #define TEXT_FOR_HIGHMEM(xx)
 864 #endif
 865
 866 #define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
 867                                         TEXT_FOR_HIGHMEM(xx) xx "_movable",
 868
 869 static const char * const vmstat_text[] = {
 870         /* Zoned VM counters */
 871         "nr_free_pages",
 872         "nr_inactive_anon",
 873         "nr_active_anon",
 874         "nr_inactive_file",
 875         "nr_active_file",
 876         "nr_unevictable",
 877         "nr_mlock",
 878         "nr_anon_pages",
 879         "nr_mapped",
 880         "nr_file_pages",
 881         "nr_dirty",
 882         "nr_writeback",
 883         "nr_slab_reclaimable",
 884         "nr_slab_unreclaimable",
 885         "nr_page_table_pages",
 886         "nr_kernel_stack",
 887         "nr_unstable",
 888         "nr_bounce",
 889         "nr_vmscan_write",
 890         "nr_writeback_temp",
 891         "nr_isolated_anon",
 892         "nr_isolated_file",
 893         "nr_shmem",
 894         "nr_dirtied",
 895         "nr_written",
 896
 897 #ifdef CONFIG_NUMA
 898         "numa_hit",
 899         "numa_miss",
 900         "numa_foreign",
 901         "numa_interleave",
 902         "numa_local",
 903         "numa_other",
 904 #endif
 905         "nr_dirty_threshold",
 906         "nr_dirty_background_threshold",
 907
 908 #ifdef CONFIG_VM_EVENT_COUNTERS
 909         "pgpgin",
 910         "pgpgout",
 911         "pswpin",
 912         "pswpout",
 913
 914         TEXTS_FOR_ZONES("pgalloc")
 915
 916         "pgfree",
 917         "pgactivate",
 918         "pgdeactivate",
 919
 920         "pgfault",
 921         "pgmajfault",
 922
 923         TEXTS_FOR_ZONES("pgrefill")
 924         TEXTS_FOR_ZONES("pgsteal")
 925         TEXTS_FOR_ZONES("pgscan_kswapd")
 926         TEXTS_FOR_ZONES("pgscan_direct")
 927
 928 #ifdef CONFIG_NUMA
 929         "zone_reclaim_failed",
 930 #endif
 931         "pginodesteal",
 932         "slabs_scanned",
 933         "kswapd_steal",
 934         "kswapd_inodesteal",
 935         "kswapd_low_wmark_hit_quickly",
 936         "kswapd_high_wmark_hit_quickly",
 937         "kswapd_skip_congestion_wait",
 938         "pageoutrun",
 939         "allocstall",
 940
 941         "pgrotated",
 942
 943 #ifdef CONFIG_COMPACTION
 944         "compact_blocks_moved",
 945         "compact_pages_moved",
 946         "compact_pagemigrate_failed",
 947         "compact_stall",
 948         "compact_fail",
 949         "compact_success",
 950 #endif
 951
 952 #ifdef CONFIG_HUGETLB_PAGE
 953         "htlb_buddy_alloc_success",
 954         "htlb_buddy_alloc_fail",
 955 #endif
 956         "unevictable_pgs_culled",
 957         "unevictable_pgs_scanned",
 958         "unevictable_pgs_rescued",
 959         "unevictable_pgs_mlocked",
 960         "unevictable_pgs_munlocked",
 961         "unevictable_pgs_cleared",
 962         "unevictable_pgs_stranded",
 963         "unevictable_pgs_mlockfreed",
 964 #endif
 965 };
 966
 967 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 968                                                         struct zone *zone)
 969 {
 970         int i;
 971         seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
 972         seq_printf(m,
 973                    "\n  pages free     %lu"
 974                    "\n        min      %lu"
 975                    "\n        low      %lu"
 976                    "\n        high     %lu"
 977                    "\n        scanned  %lu"
 978                    "\n        spanned  %lu"
 979                    "\n        present  %lu",
 980                    zone_page_state(zone, NR_FREE_PAGES),
 981                    min_wmark_pages(zone),
 982                    low_wmark_pages(zone),
 983                    high_wmark_pages(zone),
 984                    zone->pages_scanned,
 985                    zone->spanned_pages,
 986                    zone->present_pages);
 987
 988         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 989                 seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
 990                                 zone_page_state(zone, i));
 991
 992         seq_printf(m,
 993                    "\n        protection: (%lu",
 994                    zone->lowmem_reserve[0]);
 995         for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
 996                 seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
 997         seq_printf(m,
 998                    ")"
 999                    "\n  pagesets");
1000         for_each_online_cpu(i) {
1001                 struct per_cpu_pageset *pageset;
1002
1003                 pageset = per_cpu_ptr(zone->pageset, i);
1004                 seq_printf(m,
1005                            "\n    cpu: %i"
1006                            "\n              count: %i"
1007                            "\n              high:  %i"
1008                            "\n              batch: %i",
1009                            i,
1010                            pageset->pcp.count,
1011                            pageset->pcp.high,
1012                            pageset->pcp.batch);
1013 #ifdef CONFIG_SMP
1014                 seq_printf(m, "\n  vm stats threshold: %d",
1015                                 pageset->stat_threshold);
1016 #endif
1017         }
1018         seq_printf(m,
1019                    "\n  all_unreclaimable: %u"
1020                    "\n  start_pfn:         %lu"
1021                    "\n  inactive_ratio:    %u",
1022                    zone->all_unreclaimable,
1023                    zone->zone_start_pfn,
1024                    zone->inactive_ratio);
1025         seq_putc(m, '\n');
1026 }
1027
1028 /*
1029  * Output information about zones in @pgdat.
1030  */
1031 static int zoneinfo_show(struct seq_file *m, void *arg)
1032 {
1033         pg_data_t *pgdat = (pg_data_t *)arg;
1034         walk_zones_in_node(m, pgdat, zoneinfo_show_print);
1035         return 0;
1036 }
1037
1038 static const struct seq_operations zoneinfo_op = {
1039         .start  = frag_start, /* iterate over all zones. The same as in
1040                                * fragmentation. */
1041         .next   = frag_next,
1042         .stop   = frag_stop,
1043         .show   = zoneinfo_show,
1044 };
1045
1046 static int zoneinfo_open(struct inode *inode, struct file *file)
1047 {
1048         return seq_open(file, &zoneinfo_op);
1049 }
1050
1051 static const struct file_operations proc_zoneinfo_file_operations = {
1052         .open           = zoneinfo_open,
1053         .read           = seq_read,
1054         .llseek         = seq_lseek,
1055         .release        = seq_release,
1056 };
1057
1058 enum writeback_stat_item {
1059         NR_DIRTY_THRESHOLD,
1060         NR_DIRTY_BG_THRESHOLD,
1061         NR_VM_WRITEBACK_STAT_ITEMS,
1062 };
1063
1064 static void *vmstat_start(struct seq_file *m, loff_t *pos)
1065 {
1066         unsigned long *v;
1067         int i, stat_items_size;
1068
1069         if (*pos >= ARRAY_SIZE(vmstat_text))
1070                 return NULL;
1071         stat_items_size = NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long) +
1072                           NR_VM_WRITEBACK_STAT_ITEMS * sizeof(unsigned long);
1073
1074 #ifdef CONFIG_VM_EVENT_COUNTERS
1075         stat_items_size += sizeof(struct vm_event_state);
1076 #endif
1077
1078         v = kmalloc(stat_items_size, GFP_KERNEL);
1079         m->private = v;
1080         if (!v)
1081                 return ERR_PTR(-ENOMEM);
1082         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1083                 v[i] = global_page_state(i);
1084         v += NR_VM_ZONE_STAT_ITEMS;
1085
1086         global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1087                             v + NR_DIRTY_THRESHOLD);
1088         v += NR_VM_WRITEBACK_STAT_ITEMS;
1089
1090 #ifdef CONFIG_VM_EVENT_COUNTERS
1091         all_vm_events(v);
1092         v[PGPGIN] /= 2;         /* sectors -> kbytes */
1093         v[PGPGOUT] /= 2;
1094 #endif
1095         return (unsigned long *)m->private + *pos;
1096 }
1097
1098 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1099 {
1100         (*pos)++;
1101         if (*pos >= ARRAY_SIZE(vmstat_text))
1102                 return NULL;
1103         return (unsigned long *)m->private + *pos;
1104 }
1105
1106 static int vmstat_show(struct seq_file *m, void *arg)
1107 {
1108         unsigned long *l = arg;
1109         unsigned long off = l - (unsigned long *)m->private;
1110
1111         seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
1112         return 0;
1113 }
1114
1115 static void vmstat_stop(struct seq_file *m, void *arg)
1116 {
1117         kfree(m->private);
1118         m->private = NULL;
1119 }
1120
1121 static const struct seq_operations vmstat_op = {
1122         .start  = vmstat_start,
1123         .next   = vmstat_next,
1124         .stop   = vmstat_stop,
1125         .show   = vmstat_show,
1126 };
1127
1128 static int vmstat_open(struct inode *inode, struct file *file)
1129 {
1130         return seq_open(file, &vmstat_op);
1131 }
1132
1133 static const struct file_operations proc_vmstat_file_operations = {
1134         .open           = vmstat_open,
1135         .read           = seq_read,
1136         .llseek         = seq_lseek,
1137         .release        = seq_release,
1138 };
1139 #endif /* CONFIG_PROC_FS */
1140
1141 #ifdef CONFIG_SMP
1142 static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1143 int sysctl_stat_interval __read_mostly = HZ;
1144
1145 static void vmstat_update(struct work_struct *w)
1146 {
1147         refresh_cpu_vm_stats(smp_processor_id());
1148         schedule_delayed_work(&__get_cpu_var(vmstat_work),
1149                 round_jiffies_relative(sysctl_stat_interval));
1150 }
1151
1152 static void __cpuinit start_cpu_timer(int cpu)
1153 {
1154         struct delayed_work *work = &per_cpu(vmstat_work, cpu);
1155
1156         INIT_DELAYED_WORK_DEFERRABLE(work, vmstat_update);
1157         schedule_delayed_work_on(cpu, work, __round_jiffies_relative(HZ, cpu));
1158 }
1159
1160 /*
1161  * Use the cpu notifier to insure that the thresholds are recalculated
1162  * when necessary.
1163  */
1164 static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
1165                 unsigned long action,
1166                 void *hcpu)
1167 {
1168         long cpu = (long)hcpu;
1169
1170         switch (action) {
1171         case CPU_ONLINE:
1172         case CPU_ONLINE_FROZEN:
1173                 refresh_zone_stat_thresholds();
1174                 start_cpu_timer(cpu);
1175                 node_set_state(cpu_to_node(cpu), N_CPU);
1176                 break;
1177         case CPU_DOWN_PREPARE:
1178         case CPU_DOWN_PREPARE_FROZEN:
1179                 cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
1180                 per_cpu(vmstat_work, cpu).work.func = NULL;
1181                 break;
1182         case CPU_DOWN_FAILED:
1183         case CPU_DOWN_FAILED_FROZEN:
1184                 start_cpu_timer(cpu);
1185                 break;
1186         case CPU_DEAD:
1187         case CPU_DEAD_FROZEN:
1188                 refresh_zone_stat_thresholds();
1189                 break;
1190         default:
1191                 break;
1192         }
1193         return NOTIFY_OK;
1194 }
1195
1196 static struct notifier_block __cpuinitdata vmstat_notifier =
1197         { &vmstat_cpuup_callback, NULL, 0 };
1198 #endif
1199
1200 static int __init setup_vmstat(void)
1201 {
1202 #ifdef CONFIG_SMP
1203         int cpu;
1204
1205         refresh_zone_stat_thresholds();
1206         register_cpu_notifier(&vmstat_notifier);
1207
1208         for_each_online_cpu(cpu)
1209                 start_cpu_timer(cpu);
1210 #endif
1211 #ifdef CONFIG_PROC_FS
1212         proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
1213         proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
1214         proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
1215         proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
1216 #endif
1217         return 0;
1218 }
1219 module_init(setup_vmstat)
1220
1221 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
1222 #include <linux/debugfs.h>
1223
1224 static struct dentry *extfrag_debug_root;
1225
1226 /*
1227  * Return an index indicating how much of the available free memory is
1228  * unusable for an allocation of the requested size.
1229  */
1230 static int unusable_free_index(unsigned int order,
1231                                 struct contig_page_info *info)
1232 {
1233         /* No free memory is interpreted as all free memory is unusable */
1234         if (info->free_pages == 0)
1235                 return 1000;
1236
1237         /*
1238          * Index should be a value between 0 and 1. Return a value to 3
1239          * decimal places.
1240          *
1241          * 0 => no fragmentation
1242          * 1 => high fragmentation
1243          */
1244         return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
1245
1246 }
1247
1248 static void unusable_show_print(struct seq_file *m,
1249                                         pg_data_t *pgdat, struct zone *zone)
1250 {
1251         unsigned int order;
1252         int index;
1253         struct contig_page_info info;
1254
1255         seq_printf(m, "Node %d, zone %8s ",
1256                                 pgdat->node_id,
1257                                 zone->name);
1258         for (order = 0; order < MAX_ORDER; ++order) {
1259                 fill_contig_page_info(zone, order, &info);
1260                 index = unusable_free_index(order, &info);
1261                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1262         }
1263
1264         seq_putc(m, '\n');
1265 }
1266
1267 /*
1268  * Display unusable free space index
1269  *
1270  * The unusable free space index measures how much of the available free
1271  * memory cannot be used to satisfy an allocation of a given size and is a
1272  * value between 0 and 1. The higher the value, the more of free memory is
1273  * unusable and by implication, the worse the external fragmentation is. This
1274  * can be expressed as a percentage by multiplying by 100.
1275  */
1276 static int unusable_show(struct seq_file *m, void *arg)
1277 {
1278         pg_data_t *pgdat = (pg_data_t *)arg;
1279
1280         /* check memoryless node */
1281         if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
1282                 return 0;
1283
1284         walk_zones_in_node(m, pgdat, unusable_show_print);
1285
1286         return 0;
1287 }
1288
1289 static const struct seq_operations unusable_op = {
1290         .start  = frag_start,
1291         .next   = frag_next,
1292         .stop   = frag_stop,
1293         .show   = unusable_show,
1294 };
1295
1296 static int unusable_open(struct inode *inode, struct file *file)
1297 {
1298         return seq_open(file, &unusable_op);
1299 }
1300
1301 static const struct file_operations unusable_file_ops = {
1302         .open           = unusable_open,
1303         .read           = seq_read,
1304         .llseek         = seq_lseek,
1305         .release        = seq_release,
1306 };
1307
1308 static void extfrag_show_print(struct seq_file *m,
1309                                         pg_data_t *pgdat, struct zone *zone)
1310 {
1311         unsigned int order;
1312         int index;
1313
1314         /* Alloc on stack as interrupts are disabled for zone walk */
1315         struct contig_page_info info;
1316
1317         seq_printf(m, "Node %d, zone %8s ",
1318                                 pgdat->node_id,
1319                                 zone->name);
1320         for (order = 0; order < MAX_ORDER; ++order) {
1321                 fill_contig_page_info(zone, order, &info);
1322                 index = __fragmentation_index(order, &info);
1323                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1324         }
1325
1326         seq_putc(m, '\n');
1327 }
1328
1329 /*
1330  * Display fragmentation index for orders that allocations would fail for
1331  */
1332 static int extfrag_show(struct seq_file *m, void *arg)
1333 {
1334         pg_data_t *pgdat = (pg_data_t *)arg;
1335
1336         walk_zones_in_node(m, pgdat, extfrag_show_print);
1337
1338         return 0;
1339 }
1340
1341 static const struct seq_operations extfrag_op = {
1342         .start  = frag_start,
1343         .next   = frag_next,
1344         .stop   = frag_stop,
1345         .show   = extfrag_show,
1346 };
1347
1348 static int extfrag_open(struct inode *inode, struct file *file)
1349 {
1350         return seq_open(file, &extfrag_op);
1351 }
1352
1353 static const struct file_operations extfrag_file_ops = {
1354         .open           = extfrag_open,
1355         .read           = seq_read,
1356         .llseek         = seq_lseek,
1357         .release        = seq_release,
1358 };
1359
1360 static int __init extfrag_debug_init(void)
1361 {
1362         extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
1363         if (!extfrag_debug_root)
1364                 return -ENOMEM;
1365
1366         if (!debugfs_create_file("unusable_index", 0444,
1367                         extfrag_debug_root, NULL, &unusable_file_ops))
1368                 return -ENOMEM;
1369
1370         if (!debugfs_create_file("extfrag_index", 0444,
1371                         extfrag_debug_root, NULL, &extfrag_file_ops))
1372                 return -ENOMEM;
1373
1374         return 0;
1375 }
1376
1377 module_init(extfrag_debug_init);
1378 #endif