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
  12 #include <linux/mm.h>
  13 #include <linux/module.h>
  14 #include <linux/cpu.h>
  15
  16 void __get_zone_counts(unsigned long *active, unsigned long *inactive,
  17                         unsigned long *free, struct pglist_data *pgdat)
  18 {
  19         struct zone *zones = pgdat->node_zones;
  20         int i;
  21
  22         *active = 0;
  23         *inactive = 0;
  24         *free = 0;
  25         for (i = 0; i < MAX_NR_ZONES; i++) {
  26                 *active += zones[i].nr_active;
  27                 *inactive += zones[i].nr_inactive;
  28                 *free += zones[i].free_pages;
  29         }
  30 }
  31
  32 void get_zone_counts(unsigned long *active,
  33                 unsigned long *inactive, unsigned long *free)
  34 {
  35         struct pglist_data *pgdat;
  36
  37         *active = 0;
  38         *inactive = 0;
  39         *free = 0;
  40         for_each_online_pgdat(pgdat) {
  41                 unsigned long l, m, n;
  42                 __get_zone_counts(&l, &m, &n, pgdat);
  43                 *active += l;
  44                 *inactive += m;
  45                 *free += n;
  46         }
  47 }
  48
  49 #ifdef CONFIG_VM_EVENT_COUNTERS
  50 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
  51 EXPORT_PER_CPU_SYMBOL(vm_event_states);
  52
  53 static void sum_vm_events(unsigned long *ret, cpumask_t *cpumask)
  54 {
  55         int cpu = 0;
  56         int i;
  57
  58         memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
  59
  60         cpu = first_cpu(*cpumask);
  61         while (cpu < NR_CPUS) {
  62                 struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
  63
  64                 cpu = next_cpu(cpu, *cpumask);
  65
  66                 if (cpu < NR_CPUS)
  67                         prefetch(&per_cpu(vm_event_states, cpu));
  68
  69
  70                 for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
  71                         ret[i] += this->event[i];
  72         }
  73 }
  74
  75 /*
  76  * Accumulate the vm event counters across all CPUs.
  77  * The result is unavoidably approximate - it can change
  78  * during and after execution of this function.
  79 */
  80 void all_vm_events(unsigned long *ret)
  81 {
  82         sum_vm_events(ret, &cpu_online_map);
  83 }
  84 EXPORT_SYMBOL_GPL(all_vm_events);
  85
  86 #ifdef CONFIG_HOTPLUG
  87 /*
  88  * Fold the foreign cpu events into our own.
  89  *
  90  * This is adding to the events on one processor
  91  * but keeps the global counts constant.
  92  */
  93 void vm_events_fold_cpu(int cpu)
  94 {
  95         struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
  96         int i;
  97
  98         for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
  99                 count_vm_events(i, fold_state->event[i]);
 100                 fold_state->event[i] = 0;
 101         }
 102 }
 103 #endif /* CONFIG_HOTPLUG */
 104
 105 #endif /* CONFIG_VM_EVENT_COUNTERS */
 106
 107 /*
 108  * Manage combined zone based / global counters
 109  *
 110  * vm_stat contains the global counters
 111  */
 112 atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
 113 EXPORT_SYMBOL(vm_stat);
 114
 115 #ifdef CONFIG_SMP
 116
 117 static int calculate_threshold(struct zone *zone)
 118 {
 119         int threshold;
 120         int mem;        /* memory in 128 MB units */
 121
 122         /*
 123          * The threshold scales with the number of processors and the amount
 124          * of memory per zone. More memory means that we can defer updates for
 125          * longer, more processors could lead to more contention.
 126          * fls() is used to have a cheap way of logarithmic scaling.
 127          *
 128          * Some sample thresholds:
 129          *
 130          * Threshold    Processors      (fls)   Zonesize        fls(mem+1)
 131          * ------------------------------------------------------------------
 132          * 8            1               1       0.9-1 GB        4
 133          * 16           2               2       0.9-1 GB        4
 134          * 20           2               2       1-2 GB          5
 135          * 24           2               2       2-4 GB          6
 136          * 28           2               2       4-8 GB          7
 137          * 32           2               2       8-16 GB         8
 138          * 4            2               2       <128M           1
 139          * 30           4               3       2-4 GB          5
 140          * 48           4               3       8-16 GB         8
 141          * 32           8               4       1-2 GB          4
 142          * 32           8               4       0.9-1GB         4
 143          * 10           16              5       <128M           1
 144          * 40           16              5       900M            4
 145          * 70           64              7       2-4 GB          5
 146          * 84           64              7       4-8 GB          6
 147          * 108          512             9       4-8 GB          6
 148          * 125          1024            10      8-16 GB         8
 149          * 125          1024            10      16-32 GB        9
 150          */
 151
 152         mem = zone->present_pages >> (27 - PAGE_SHIFT);
 153
 154         threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
 155
 156         /*
 157          * Maximum threshold is 125
 158          */
 159         threshold = min(125, threshold);
 160
 161         return threshold;
 162 }
 163
 164 /*
 165  * Refresh the thresholds for each zone.
 166  */
 167 static void refresh_zone_stat_thresholds(void)
 168 {
 169         struct zone *zone;
 170         int cpu;
 171         int threshold;
 172
 173         for_each_zone(zone) {
 174
 175                 if (!zone->present_pages)
 176                         continue;
 177
 178                 threshold = calculate_threshold(zone);
 179
 180                 for_each_online_cpu(cpu)
 181                         zone_pcp(zone, cpu)->stat_threshold = threshold;
 182         }
 183 }
 184
 185 /*
 186  * For use when we know that interrupts are disabled.
 187  */
 188 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 189                                 int delta)
 190 {
 191         struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
 192         s8 *p = pcp->vm_stat_diff + item;
 193         long x;
 194
 195         x = delta + *p;
 196
 197         if (unlikely(x > pcp->stat_threshold || x < -pcp->stat_threshold)) {
 198                 zone_page_state_add(x, zone, item);
 199                 x = 0;
 200         }
 201         *p = x;
 202 }
 203 EXPORT_SYMBOL(__mod_zone_page_state);
 204
 205 /*
 206  * For an unknown interrupt state
 207  */
 208 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 209                                         int delta)
 210 {
 211         unsigned long flags;
 212
 213         local_irq_save(flags);
 214         __mod_zone_page_state(zone, item, delta);
 215         local_irq_restore(flags);
 216 }
 217 EXPORT_SYMBOL(mod_zone_page_state);
 218
 219 /*
 220  * Optimized increment and decrement functions.
 221  *
 222  * These are only for a single page and therefore can take a struct page *
 223  * argument instead of struct zone *. This allows the inclusion of the code
 224  * generated for page_zone(page) into the optimized functions.
 225  *
 226  * No overflow check is necessary and therefore the differential can be
 227  * incremented or decremented in place which may allow the compilers to
 228  * generate better code.
 229  * The increment or decrement is known and therefore one boundary check can
 230  * be omitted.
 231  *
 232  * NOTE: These functions are very performance sensitive. Change only
 233  * with care.
 234  *
 235  * Some processors have inc/dec instructions that are atomic vs an interrupt.
 236  * However, the code must first determine the differential location in a zone
 237  * based on the processor number and then inc/dec the counter. There is no
 238  * guarantee without disabling preemption that the processor will not change
 239  * in between and therefore the atomicity vs. interrupt cannot be exploited
 240  * in a useful way here.
 241  */
 242 static void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 243 {
 244         struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
 245         s8 *p = pcp->vm_stat_diff + item;
 246
 247         (*p)++;
 248
 249         if (unlikely(*p > pcp->stat_threshold)) {
 250                 int overstep = pcp->stat_threshold / 2;
 251
 252                 zone_page_state_add(*p + overstep, zone, item);
 253                 *p = -overstep;
 254         }
 255 }
 256
 257 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
 258 {
 259         __inc_zone_state(page_zone(page), item);
 260 }
 261 EXPORT_SYMBOL(__inc_zone_page_state);
 262
 263 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
 264 {
 265         struct zone *zone = page_zone(page);
 266         struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
 267         s8 *p = pcp->vm_stat_diff + item;
 268
 269         (*p)--;
 270
 271         if (unlikely(*p < - pcp->stat_threshold)) {
 272                 int overstep = pcp->stat_threshold / 2;
 273
 274                 zone_page_state_add(*p - overstep, zone, item);
 275                 *p = overstep;
 276         }
 277 }
 278 EXPORT_SYMBOL(__dec_zone_page_state);
 279
 280 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
 281 {
 282         unsigned long flags;
 283
 284         local_irq_save(flags);
 285         __inc_zone_state(zone, item);
 286         local_irq_restore(flags);
 287 }
 288
 289 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 290 {
 291         unsigned long flags;
 292         struct zone *zone;
 293
 294         zone = page_zone(page);
 295         local_irq_save(flags);
 296         __inc_zone_state(zone, item);
 297         local_irq_restore(flags);
 298 }
 299 EXPORT_SYMBOL(inc_zone_page_state);
 300
 301 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 302 {
 303         unsigned long flags;
 304
 305         local_irq_save(flags);
 306         __dec_zone_page_state(page, item);
 307         local_irq_restore(flags);
 308 }
 309 EXPORT_SYMBOL(dec_zone_page_state);
 310
 311 /*
 312  * Update the zone counters for one cpu.
 313  */
 314 void refresh_cpu_vm_stats(int cpu)
 315 {
 316         struct zone *zone;
 317         int i;
 318         unsigned long flags;
 319
 320         for_each_zone(zone) {
 321                 struct per_cpu_pageset *pcp;
 322
 323                 if (!populated_zone(zone))
 324                         continue;
 325
 326                 pcp = zone_pcp(zone, cpu);
 327
 328                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 329                         if (pcp->vm_stat_diff[i]) {
 330                                 local_irq_save(flags);
 331                                 zone_page_state_add(pcp->vm_stat_diff[i],
 332                                         zone, i);
 333                                 pcp->vm_stat_diff[i] = 0;
 334                                 local_irq_restore(flags);
 335                         }
 336         }
 337 }
 338
 339 static void __refresh_cpu_vm_stats(void *dummy)
 340 {
 341         refresh_cpu_vm_stats(smp_processor_id());
 342 }
 343
 344 /*
 345  * Consolidate all counters.
 346  *
 347  * Note that the result is less inaccurate but still inaccurate
 348  * if concurrent processes are allowed to run.
 349  */
 350 void refresh_vm_stats(void)
 351 {
 352         on_each_cpu(__refresh_cpu_vm_stats, NULL, 0, 1);
 353 }
 354 EXPORT_SYMBOL(refresh_vm_stats);
 355
 356 #endif
 357
 358 #ifdef CONFIG_NUMA
 359 /*
 360  * zonelist = the list of zones passed to the allocator
 361  * z        = the zone from which the allocation occurred.
 362  *
 363  * Must be called with interrupts disabled.
 364  */
 365 void zone_statistics(struct zonelist *zonelist, struct zone *z)
 366 {
 367         if (z->zone_pgdat == zonelist->zones[0]->zone_pgdat) {
 368                 __inc_zone_state(z, NUMA_HIT);
 369         } else {
 370                 __inc_zone_state(z, NUMA_MISS);
 371                 __inc_zone_state(zonelist->zones[0], NUMA_FOREIGN);
 372         }
 373         if (z->node == numa_node_id())
 374                 __inc_zone_state(z, NUMA_LOCAL);
 375         else
 376                 __inc_zone_state(z, NUMA_OTHER);
 377 }
 378 #endif
 379
 380 #ifdef CONFIG_PROC_FS
 381
 382 #include <linux/seq_file.h>
 383
 384 static void *frag_start(struct seq_file *m, loff_t *pos)
 385 {
 386         pg_data_t *pgdat;
 387         loff_t node = *pos;
 388         for (pgdat = first_online_pgdat();
 389              pgdat && node;
 390              pgdat = next_online_pgdat(pgdat))
 391                 --node;
 392
 393         return pgdat;
 394 }
 395
 396 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
 397 {
 398         pg_data_t *pgdat = (pg_data_t *)arg;
 399
 400         (*pos)++;
 401         return next_online_pgdat(pgdat);
 402 }
 403
 404 static void frag_stop(struct seq_file *m, void *arg)
 405 {
 406 }
 407
 408 /*
 409  * This walks the free areas for each zone.
 410  */
 411 static int frag_show(struct seq_file *m, void *arg)
 412 {
 413         pg_data_t *pgdat = (pg_data_t *)arg;
 414         struct zone *zone;
 415         struct zone *node_zones = pgdat->node_zones;
 416         unsigned long flags;
 417         int order;
 418
 419         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
 420                 if (!populated_zone(zone))
 421                         continue;
 422
 423                 spin_lock_irqsave(&zone->lock, flags);
 424                 seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 425                 for (order = 0; order < MAX_ORDER; ++order)
 426                         seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
 427                 spin_unlock_irqrestore(&zone->lock, flags);
 428                 seq_putc(m, '\n');
 429         }
 430         return 0;
 431 }
 432
 433 const struct seq_operations fragmentation_op = {
 434         .start  = frag_start,
 435         .next   = frag_next,
 436         .stop   = frag_stop,
 437         .show   = frag_show,
 438 };
 439
 440 #ifdef CONFIG_ZONE_DMA32
 441 #define TEXT_FOR_DMA32(xx) xx "_dma32",
 442 #else
 443 #define TEXT_FOR_DMA32(xx)
 444 #endif
 445
 446 #ifdef CONFIG_HIGHMEM
 447 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
 448 #else
 449 #define TEXT_FOR_HIGHMEM(xx)
 450 #endif
 451
 452 #define TEXTS_FOR_ZONES(xx) xx "_dma", TEXT_FOR_DMA32(xx) xx "_normal", \
 453                                         TEXT_FOR_HIGHMEM(xx)
 454
 455 static const char * const vmstat_text[] = {
 456         /* Zoned VM counters */
 457         "nr_anon_pages",
 458         "nr_mapped",
 459         "nr_file_pages",
 460         "nr_slab_reclaimable",
 461         "nr_slab_unreclaimable",
 462         "nr_page_table_pages",
 463         "nr_dirty",
 464         "nr_writeback",
 465         "nr_unstable",
 466         "nr_bounce",
 467         "nr_vmscan_write",
 468
 469 #ifdef CONFIG_NUMA
 470         "numa_hit",
 471         "numa_miss",
 472         "numa_foreign",
 473         "numa_interleave",
 474         "numa_local",
 475         "numa_other",
 476 #endif
 477
 478 #ifdef CONFIG_VM_EVENT_COUNTERS
 479         "pgpgin",
 480         "pgpgout",
 481         "pswpin",
 482         "pswpout",
 483
 484         TEXTS_FOR_ZONES("pgalloc")
 485
 486         "pgfree",
 487         "pgactivate",
 488         "pgdeactivate",
 489
 490         "pgfault",
 491         "pgmajfault",
 492
 493         TEXTS_FOR_ZONES("pgrefill")
 494         TEXTS_FOR_ZONES("pgsteal")
 495         TEXTS_FOR_ZONES("pgscan_kswapd")
 496         TEXTS_FOR_ZONES("pgscan_direct")
 497
 498         "pginodesteal",
 499         "slabs_scanned",
 500         "kswapd_steal",
 501         "kswapd_inodesteal",
 502         "pageoutrun",
 503         "allocstall",
 504
 505         "pgrotated",
 506 #endif
 507 };
 508
 509 /*
 510  * Output information about zones in @pgdat.
 511  */
 512 static int zoneinfo_show(struct seq_file *m, void *arg)
 513 {
 514         pg_data_t *pgdat = arg;
 515         struct zone *zone;
 516         struct zone *node_zones = pgdat->node_zones;
 517         unsigned long flags;
 518
 519         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; zone++) {
 520                 int i;
 521
 522                 if (!populated_zone(zone))
 523                         continue;
 524
 525                 spin_lock_irqsave(&zone->lock, flags);
 526                 seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
 527                 seq_printf(m,
 528                            "\n  pages free     %lu"
 529                            "\n        min      %lu"
 530                            "\n        low      %lu"
 531                            "\n        high     %lu"
 532                            "\n        active   %lu"
 533                            "\n        inactive %lu"
 534                            "\n        scanned  %lu (a: %lu i: %lu)"
 535                            "\n        spanned  %lu"
 536                            "\n        present  %lu",
 537                            zone->free_pages,
 538                            zone->pages_min,
 539                            zone->pages_low,
 540                            zone->pages_high,
 541                            zone->nr_active,
 542                            zone->nr_inactive,
 543                            zone->pages_scanned,
 544                            zone->nr_scan_active, zone->nr_scan_inactive,
 545                            zone->spanned_pages,
 546                            zone->present_pages);
 547
 548                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 549                         seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
 550                                         zone_page_state(zone, i));
 551
 552                 seq_printf(m,
 553                            "\n        protection: (%lu",
 554                            zone->lowmem_reserve[0]);
 555                 for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
 556                         seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
 557                 seq_printf(m,
 558                            ")"
 559                            "\n  pagesets");
 560                 for_each_online_cpu(i) {
 561                         struct per_cpu_pageset *pageset;
 562                         int j;
 563
 564                         pageset = zone_pcp(zone, i);
 565                         for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
 566                                 if (pageset->pcp[j].count)
 567                                         break;
 568                         }
 569                         if (j == ARRAY_SIZE(pageset->pcp))
 570                                 continue;
 571                         for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
 572                                 seq_printf(m,
 573                                            "\n    cpu: %i pcp: %i"
 574                                            "\n              count: %i"
 575                                            "\n              high:  %i"
 576                                            "\n              batch: %i",
 577                                            i, j,
 578                                            pageset->pcp[j].count,
 579                                            pageset->pcp[j].high,
 580                                            pageset->pcp[j].batch);
 581                         }
 582 #ifdef CONFIG_SMP
 583                         seq_printf(m, "\n  vm stats threshold: %d",
 584                                         pageset->stat_threshold);
 585 #endif
 586                 }
 587                 seq_printf(m,
 588                            "\n  all_unreclaimable: %u"
 589                            "\n  prev_priority:     %i"
 590                            "\n  start_pfn:         %lu",
 591                            zone->all_unreclaimable,
 592                            zone->prev_priority,
 593                            zone->zone_start_pfn);
 594                 spin_unlock_irqrestore(&zone->lock, flags);
 595                 seq_putc(m, '\n');
 596         }
 597         return 0;
 598 }
 599
 600 const struct seq_operations zoneinfo_op = {
 601         .start  = frag_start, /* iterate over all zones. The same as in
 602                                * fragmentation. */
 603         .next   = frag_next,
 604         .stop   = frag_stop,
 605         .show   = zoneinfo_show,
 606 };
 607
 608 static void *vmstat_start(struct seq_file *m, loff_t *pos)
 609 {
 610         unsigned long *v;
 611 #ifdef CONFIG_VM_EVENT_COUNTERS
 612         unsigned long *e;
 613 #endif
 614         int i;
 615
 616         if (*pos >= ARRAY_SIZE(vmstat_text))
 617                 return NULL;
 618
 619 #ifdef CONFIG_VM_EVENT_COUNTERS
 620         v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long)
 621                         + sizeof(struct vm_event_state), GFP_KERNEL);
 622 #else
 623         v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long),
 624                         GFP_KERNEL);
 625 #endif
 626         m->private = v;
 627         if (!v)
 628                 return ERR_PTR(-ENOMEM);
 629         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 630                 v[i] = global_page_state(i);
 631 #ifdef CONFIG_VM_EVENT_COUNTERS
 632         e = v + NR_VM_ZONE_STAT_ITEMS;
 633         all_vm_events(e);
 634         e[PGPGIN] /= 2;         /* sectors -> kbytes */
 635         e[PGPGOUT] /= 2;
 636 #endif
 637         return v + *pos;
 638 }
 639
 640 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
 641 {
 642         (*pos)++;
 643         if (*pos >= ARRAY_SIZE(vmstat_text))
 644                 return NULL;
 645         return (unsigned long *)m->private + *pos;
 646 }
 647
 648 static int vmstat_show(struct seq_file *m, void *arg)
 649 {
 650         unsigned long *l = arg;
 651         unsigned long off = l - (unsigned long *)m->private;
 652
 653         seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
 654         return 0;
 655 }
 656
 657 static void vmstat_stop(struct seq_file *m, void *arg)
 658 {
 659         kfree(m->private);
 660         m->private = NULL;
 661 }
 662
 663 const struct seq_operations vmstat_op = {
 664         .start  = vmstat_start,
 665         .next   = vmstat_next,
 666         .stop   = vmstat_stop,
 667         .show   = vmstat_show,
 668 };
 669
 670 #endif /* CONFIG_PROC_FS */
 671
 672 #ifdef CONFIG_SMP
 673 /*
 674  * Use the cpu notifier to insure that the thresholds are recalculated
 675  * when necessary.
 676  */
 677 static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
 678                 unsigned long action,
 679                 void *hcpu)
 680 {
 681         switch (action) {
 682         case CPU_UP_PREPARE:
 683         case CPU_UP_CANCELED:
 684         case CPU_DEAD:
 685                 refresh_zone_stat_thresholds();
 686                 break;
 687         default:
 688                 break;
 689         }
 690         return NOTIFY_OK;
 691 }
 692
 693 static struct notifier_block __cpuinitdata vmstat_notifier =
 694         { &vmstat_cpuup_callback, NULL, 0 };
 695
 696 int __init setup_vmstat(void)
 697 {
 698         refresh_zone_stat_thresholds();
 699         register_cpu_notifier(&vmstat_notifier);
 700         return 0;
 701 }
 702 module_init(setup_vmstat)
 703 #endif