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