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Linux/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  *  Copyright (C) 2008-2014 Christoph Lameter
 11  */
 12 #include <linux/fs.h>
 13 #include <linux/mm.h>
 14 #include <linux/err.h>
 15 #include <linux/module.h>
 16 #include <linux/slab.h>
 17 #include <linux/cpu.h>
 18 #include <linux/cpumask.h>
 19 #include <linux/vmstat.h>
 20 #include <linux/proc_fs.h>
 21 #include <linux/seq_file.h>
 22 #include <linux/debugfs.h>
 23 #include <linux/sched.h>
 24 #include <linux/math64.h>
 25 #include <linux/writeback.h>
 26 #include <linux/compaction.h>
 27 #include <linux/mm_inline.h>
 28 #include <linux/page_ext.h>
 29 #include <linux/page_owner.h>
 30 
 31 #include "internal.h"
 32 
 33 #ifdef CONFIG_VM_EVENT_COUNTERS
 34 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
 35 EXPORT_PER_CPU_SYMBOL(vm_event_states);
 36 
 37 static void sum_vm_events(unsigned long *ret)
 38 {
 39         int cpu;
 40         int i;
 41 
 42         memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
 43 
 44         for_each_online_cpu(cpu) {
 45                 struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
 46 
 47                 for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
 48                         ret[i] += this->event[i];
 49         }
 50 }
 51 
 52 /*
 53  * Accumulate the vm event counters across all CPUs.
 54  * The result is unavoidably approximate - it can change
 55  * during and after execution of this function.
 56 */
 57 void all_vm_events(unsigned long *ret)
 58 {
 59         get_online_cpus();
 60         sum_vm_events(ret);
 61         put_online_cpus();
 62 }
 63 EXPORT_SYMBOL_GPL(all_vm_events);
 64 
 65 /*
 66  * Fold the foreign cpu events into our own.
 67  *
 68  * This is adding to the events on one processor
 69  * but keeps the global counts constant.
 70  */
 71 void vm_events_fold_cpu(int cpu)
 72 {
 73         struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
 74         int i;
 75 
 76         for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
 77                 count_vm_events(i, fold_state->event[i]);
 78                 fold_state->event[i] = 0;
 79         }
 80 }
 81 
 82 #endif /* CONFIG_VM_EVENT_COUNTERS */
 83 
 84 /*
 85  * Manage combined zone based / global counters
 86  *
 87  * vm_stat contains the global counters
 88  */
 89 atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp;
 90 EXPORT_SYMBOL(vm_stat);
 91 
 92 #ifdef CONFIG_SMP
 93 
 94 int calculate_pressure_threshold(struct zone *zone)
 95 {
 96         int threshold;
 97         int watermark_distance;
 98 
 99         /*
100          * As vmstats are not up to date, there is drift between the estimated
101          * and real values. For high thresholds and a high number of CPUs, it
102          * is possible for the min watermark to be breached while the estimated
103          * value looks fine. The pressure threshold is a reduced value such
104          * that even the maximum amount of drift will not accidentally breach
105          * the min watermark
106          */
107         watermark_distance = low_wmark_pages(zone) - min_wmark_pages(zone);
108         threshold = max(1, (int)(watermark_distance / num_online_cpus()));
109 
110         /*
111          * Maximum threshold is 125
112          */
113         threshold = min(125, threshold);
114 
115         return threshold;
116 }
117 
118 int calculate_normal_threshold(struct zone *zone)
119 {
120         int threshold;
121         int mem;        /* memory in 128 MB units */
122 
123         /*
124          * The threshold scales with the number of processors and the amount
125          * of memory per zone. More memory means that we can defer updates for
126          * longer, more processors could lead to more contention.
127          * fls() is used to have a cheap way of logarithmic scaling.
128          *
129          * Some sample thresholds:
130          *
131          * Threshold    Processors      (fls)   Zonesize        fls(mem+1)
132          * ------------------------------------------------------------------
133          * 8            1               1       0.9-1 GB        4
134          * 16           2               2       0.9-1 GB        4
135          * 20           2               2       1-2 GB          5
136          * 24           2               2       2-4 GB          6
137          * 28           2               2       4-8 GB          7
138          * 32           2               2       8-16 GB         8
139          * 4            2               2       <128M           1
140          * 30           4               3       2-4 GB          5
141          * 48           4               3       8-16 GB         8
142          * 32           8               4       1-2 GB          4
143          * 32           8               4       0.9-1GB         4
144          * 10           16              5       <128M           1
145          * 40           16              5       900M            4
146          * 70           64              7       2-4 GB          5
147          * 84           64              7       4-8 GB          6
148          * 108          512             9       4-8 GB          6
149          * 125          1024            10      8-16 GB         8
150          * 125          1024            10      16-32 GB        9
151          */
152 
153         mem = zone->managed_pages >> (27 - PAGE_SHIFT);
154 
155         threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
156 
157         /*
158          * Maximum threshold is 125
159          */
160         threshold = min(125, threshold);
161 
162         return threshold;
163 }
164 
165 /*
166  * Refresh the thresholds for each zone.
167  */
168 void refresh_zone_stat_thresholds(void)
169 {
170         struct zone *zone;
171         int cpu;
172         int threshold;
173 
174         for_each_populated_zone(zone) {
175                 unsigned long max_drift, tolerate_drift;
176 
177                 threshold = calculate_normal_threshold(zone);
178 
179                 for_each_online_cpu(cpu)
180                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
181                                                         = threshold;
182 
183                 /*
184                  * Only set percpu_drift_mark if there is a danger that
185                  * NR_FREE_PAGES reports the low watermark is ok when in fact
186                  * the min watermark could be breached by an allocation
187                  */
188                 tolerate_drift = low_wmark_pages(zone) - min_wmark_pages(zone);
189                 max_drift = num_online_cpus() * threshold;
190                 if (max_drift > tolerate_drift)
191                         zone->percpu_drift_mark = high_wmark_pages(zone) +
192                                         max_drift;
193         }
194 }
195 
196 void set_pgdat_percpu_threshold(pg_data_t *pgdat,
197                                 int (*calculate_pressure)(struct zone *))
198 {
199         struct zone *zone;
200         int cpu;
201         int threshold;
202         int i;
203 
204         for (i = 0; i < pgdat->nr_zones; i++) {
205                 zone = &pgdat->node_zones[i];
206                 if (!zone->percpu_drift_mark)
207                         continue;
208 
209                 threshold = (*calculate_pressure)(zone);
210                 for_each_online_cpu(cpu)
211                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
212                                                         = threshold;
213         }
214 }
215 
216 /*
217  * For use when we know that interrupts are disabled,
218  * or when we know that preemption is disabled and that
219  * particular counter cannot be updated from interrupt context.
220  */
221 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
222                                 int delta)
223 {
224         struct per_cpu_pageset __percpu *pcp = zone->pageset;
225         s8 __percpu *p = pcp->vm_stat_diff + item;
226         long x;
227         long t;
228 
229         x = delta + __this_cpu_read(*p);
230 
231         t = __this_cpu_read(pcp->stat_threshold);
232 
233         if (unlikely(x > t || x < -t)) {
234                 zone_page_state_add(x, zone, item);
235                 x = 0;
236         }
237         __this_cpu_write(*p, x);
238 }
239 EXPORT_SYMBOL(__mod_zone_page_state);
240 
241 /*
242  * Optimized increment and decrement functions.
243  *
244  * These are only for a single page and therefore can take a struct page *
245  * argument instead of struct zone *. This allows the inclusion of the code
246  * generated for page_zone(page) into the optimized functions.
247  *
248  * No overflow check is necessary and therefore the differential can be
249  * incremented or decremented in place which may allow the compilers to
250  * generate better code.
251  * The increment or decrement is known and therefore one boundary check can
252  * be omitted.
253  *
254  * NOTE: These functions are very performance sensitive. Change only
255  * with care.
256  *
257  * Some processors have inc/dec instructions that are atomic vs an interrupt.
258  * However, the code must first determine the differential location in a zone
259  * based on the processor number and then inc/dec the counter. There is no
260  * guarantee without disabling preemption that the processor will not change
261  * in between and therefore the atomicity vs. interrupt cannot be exploited
262  * in a useful way here.
263  */
264 void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
265 {
266         struct per_cpu_pageset __percpu *pcp = zone->pageset;
267         s8 __percpu *p = pcp->vm_stat_diff + item;
268         s8 v, t;
269 
270         v = __this_cpu_inc_return(*p);
271         t = __this_cpu_read(pcp->stat_threshold);
272         if (unlikely(v > t)) {
273                 s8 overstep = t >> 1;
274 
275                 zone_page_state_add(v + overstep, zone, item);
276                 __this_cpu_write(*p, -overstep);
277         }
278 }
279 
280 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
281 {
282         __inc_zone_state(page_zone(page), item);
283 }
284 EXPORT_SYMBOL(__inc_zone_page_state);
285 
286 void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
287 {
288         struct per_cpu_pageset __percpu *pcp = zone->pageset;
289         s8 __percpu *p = pcp->vm_stat_diff + item;
290         s8 v, t;
291 
292         v = __this_cpu_dec_return(*p);
293         t = __this_cpu_read(pcp->stat_threshold);
294         if (unlikely(v < - t)) {
295                 s8 overstep = t >> 1;
296 
297                 zone_page_state_add(v - overstep, zone, item);
298                 __this_cpu_write(*p, overstep);
299         }
300 }
301 
302 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
303 {
304         __dec_zone_state(page_zone(page), item);
305 }
306 EXPORT_SYMBOL(__dec_zone_page_state);
307 
308 #ifdef CONFIG_HAVE_CMPXCHG_LOCAL
309 /*
310  * If we have cmpxchg_local support then we do not need to incur the overhead
311  * that comes with local_irq_save/restore if we use this_cpu_cmpxchg.
312  *
313  * mod_state() modifies the zone counter state through atomic per cpu
314  * operations.
315  *
316  * Overstep mode specifies how overstep should handled:
317  *     0       No overstepping
318  *     1       Overstepping half of threshold
319  *     -1      Overstepping minus half of threshold
320 */
321 static inline void mod_state(struct zone *zone,
322        enum zone_stat_item item, int delta, int overstep_mode)
323 {
324         struct per_cpu_pageset __percpu *pcp = zone->pageset;
325         s8 __percpu *p = pcp->vm_stat_diff + item;
326         long o, n, t, z;
327 
328         do {
329                 z = 0;  /* overflow to zone counters */
330 
331                 /*
332                  * The fetching of the stat_threshold is racy. We may apply
333                  * a counter threshold to the wrong the cpu if we get
334                  * rescheduled while executing here. However, the next
335                  * counter update will apply the threshold again and
336                  * therefore bring the counter under the threshold again.
337                  *
338                  * Most of the time the thresholds are the same anyways
339                  * for all cpus in a zone.
340                  */
341                 t = this_cpu_read(pcp->stat_threshold);
342 
343                 o = this_cpu_read(*p);
344                 n = delta + o;
345 
346                 if (n > t || n < -t) {
347                         int os = overstep_mode * (t >> 1) ;
348 
349                         /* Overflow must be added to zone counters */
350                         z = n + os;
351                         n = -os;
352                 }
353         } while (this_cpu_cmpxchg(*p, o, n) != o);
354 
355         if (z)
356                 zone_page_state_add(z, zone, item);
357 }
358 
359 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
360                                         int delta)
361 {
362         mod_state(zone, item, delta, 0);
363 }
364 EXPORT_SYMBOL(mod_zone_page_state);
365 
366 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
367 {
368         mod_state(zone, item, 1, 1);
369 }
370 
371 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
372 {
373         mod_state(page_zone(page), item, 1, 1);
374 }
375 EXPORT_SYMBOL(inc_zone_page_state);
376 
377 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
378 {
379         mod_state(page_zone(page), item, -1, -1);
380 }
381 EXPORT_SYMBOL(dec_zone_page_state);
382 #else
383 /*
384  * Use interrupt disable to serialize counter updates
385  */
386 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
387                                         int delta)
388 {
389         unsigned long flags;
390 
391         local_irq_save(flags);
392         __mod_zone_page_state(zone, item, delta);
393         local_irq_restore(flags);
394 }
395 EXPORT_SYMBOL(mod_zone_page_state);
396 
397 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
398 {
399         unsigned long flags;
400 
401         local_irq_save(flags);
402         __inc_zone_state(zone, item);
403         local_irq_restore(flags);
404 }
405 
406 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
407 {
408         unsigned long flags;
409         struct zone *zone;
410 
411         zone = page_zone(page);
412         local_irq_save(flags);
413         __inc_zone_state(zone, item);
414         local_irq_restore(flags);
415 }
416 EXPORT_SYMBOL(inc_zone_page_state);
417 
418 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
419 {
420         unsigned long flags;
421 
422         local_irq_save(flags);
423         __dec_zone_page_state(page, item);
424         local_irq_restore(flags);
425 }
426 EXPORT_SYMBOL(dec_zone_page_state);
427 #endif
428 
429 
430 /*
431  * Fold a differential into the global counters.
432  * Returns the number of counters updated.
433  */
434 static int fold_diff(int *diff)
435 {
436         int i;
437         int changes = 0;
438 
439         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
440                 if (diff[i]) {
441                         atomic_long_add(diff[i], &vm_stat[i]);
442                         changes++;
443         }
444         return changes;
445 }
446 
447 /*
448  * Update the zone counters for the current cpu.
449  *
450  * Note that refresh_cpu_vm_stats strives to only access
451  * node local memory. The per cpu pagesets on remote zones are placed
452  * in the memory local to the processor using that pageset. So the
453  * loop over all zones will access a series of cachelines local to
454  * the processor.
455  *
456  * The call to zone_page_state_add updates the cachelines with the
457  * statistics in the remote zone struct as well as the global cachelines
458  * with the global counters. These could cause remote node cache line
459  * bouncing and will have to be only done when necessary.
460  *
461  * The function returns the number of global counters updated.
462  */
463 static int refresh_cpu_vm_stats(void)
464 {
465         struct zone *zone;
466         int i;
467         int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
468         int changes = 0;
469 
470         for_each_populated_zone(zone) {
471                 struct per_cpu_pageset __percpu *p = zone->pageset;
472 
473                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
474                         int v;
475 
476                         v = this_cpu_xchg(p->vm_stat_diff[i], 0);
477                         if (v) {
478 
479                                 atomic_long_add(v, &zone->vm_stat[i]);
480                                 global_diff[i] += v;
481 #ifdef CONFIG_NUMA
482                                 /* 3 seconds idle till flush */
483                                 __this_cpu_write(p->expire, 3);
484 #endif
485                         }
486                 }
487                 cond_resched();
488 #ifdef CONFIG_NUMA
489                 /*
490                  * Deal with draining the remote pageset of this
491                  * processor
492                  *
493                  * Check if there are pages remaining in this pageset
494                  * if not then there is nothing to expire.
495                  */
496                 if (!__this_cpu_read(p->expire) ||
497                                !__this_cpu_read(p->pcp.count))
498                         continue;
499 
500                 /*
501                  * We never drain zones local to this processor.
502                  */
503                 if (zone_to_nid(zone) == numa_node_id()) {
504                         __this_cpu_write(p->expire, 0);
505                         continue;
506                 }
507 
508                 if (__this_cpu_dec_return(p->expire))
509                         continue;
510 
511                 if (__this_cpu_read(p->pcp.count)) {
512                         drain_zone_pages(zone, this_cpu_ptr(&p->pcp));
513                         changes++;
514                 }
515 #endif
516         }
517         changes += fold_diff(global_diff);
518         return changes;
519 }
520 
521 /*
522  * Fold the data for an offline cpu into the global array.
523  * There cannot be any access by the offline cpu and therefore
524  * synchronization is simplified.
525  */
526 void cpu_vm_stats_fold(int cpu)
527 {
528         struct zone *zone;
529         int i;
530         int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
531 
532         for_each_populated_zone(zone) {
533                 struct per_cpu_pageset *p;
534 
535                 p = per_cpu_ptr(zone->pageset, cpu);
536 
537                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
538                         if (p->vm_stat_diff[i]) {
539                                 int v;
540 
541                                 v = p->vm_stat_diff[i];
542                                 p->vm_stat_diff[i] = 0;
543                                 atomic_long_add(v, &zone->vm_stat[i]);
544                                 global_diff[i] += v;
545                         }
546         }
547 
548         fold_diff(global_diff);
549 }
550 
551 /*
552  * this is only called if !populated_zone(zone), which implies no other users of
553  * pset->vm_stat_diff[] exsist.
554  */
555 void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset)
556 {
557         int i;
558 
559         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
560                 if (pset->vm_stat_diff[i]) {
561                         int v = pset->vm_stat_diff[i];
562                         pset->vm_stat_diff[i] = 0;
563                         atomic_long_add(v, &zone->vm_stat[i]);
564                         atomic_long_add(v, &vm_stat[i]);
565                 }
566 }
567 #endif
568 
569 #ifdef CONFIG_NUMA
570 /*
571  * zonelist = the list of zones passed to the allocator
572  * z        = the zone from which the allocation occurred.
573  *
574  * Must be called with interrupts disabled.
575  *
576  * When __GFP_OTHER_NODE is set assume the node of the preferred
577  * zone is the local node. This is useful for daemons who allocate
578  * memory on behalf of other processes.
579  */
580 void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags)
581 {
582         if (z->zone_pgdat == preferred_zone->zone_pgdat) {
583                 __inc_zone_state(z, NUMA_HIT);
584         } else {
585                 __inc_zone_state(z, NUMA_MISS);
586                 __inc_zone_state(preferred_zone, NUMA_FOREIGN);
587         }
588         if (z->node == ((flags & __GFP_OTHER_NODE) ?
589                         preferred_zone->node : numa_node_id()))
590                 __inc_zone_state(z, NUMA_LOCAL);
591         else
592                 __inc_zone_state(z, NUMA_OTHER);
593 }
594 #endif
595 
596 #ifdef CONFIG_COMPACTION
597 
598 struct contig_page_info {
599         unsigned long free_pages;
600         unsigned long free_blocks_total;
601         unsigned long free_blocks_suitable;
602 };
603 
604 /*
605  * Calculate the number of free pages in a zone, how many contiguous
606  * pages are free and how many are large enough to satisfy an allocation of
607  * the target size. Note that this function makes no attempt to estimate
608  * how many suitable free blocks there *might* be if MOVABLE pages were
609  * migrated. Calculating that is possible, but expensive and can be
610  * figured out from userspace
611  */
612 static void fill_contig_page_info(struct zone *zone,
613                                 unsigned int suitable_order,
614                                 struct contig_page_info *info)
615 {
616         unsigned int order;
617 
618         info->free_pages = 0;
619         info->free_blocks_total = 0;
620         info->free_blocks_suitable = 0;
621 
622         for (order = 0; order < MAX_ORDER; order++) {
623                 unsigned long blocks;
624 
625                 /* Count number of free blocks */
626                 blocks = zone->free_area[order].nr_free;
627                 info->free_blocks_total += blocks;
628 
629                 /* Count free base pages */
630                 info->free_pages += blocks << order;
631 
632                 /* Count the suitable free blocks */
633                 if (order >= suitable_order)
634                         info->free_blocks_suitable += blocks <<
635                                                 (order - suitable_order);
636         }
637 }
638 
639 /*
640  * A fragmentation index only makes sense if an allocation of a requested
641  * size would fail. If that is true, the fragmentation index indicates
642  * whether external fragmentation or a lack of memory was the problem.
643  * The value can be used to determine if page reclaim or compaction
644  * should be used
645  */
646 static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
647 {
648         unsigned long requested = 1UL << order;
649 
650         if (!info->free_blocks_total)
651                 return 0;
652 
653         /* Fragmentation index only makes sense when a request would fail */
654         if (info->free_blocks_suitable)
655                 return -1000;
656 
657         /*
658          * Index is between 0 and 1 so return within 3 decimal places
659          *
660          * 0 => allocation would fail due to lack of memory
661          * 1 => allocation would fail due to fragmentation
662          */
663         return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
664 }
665 
666 /* Same as __fragmentation index but allocs contig_page_info on stack */
667 int fragmentation_index(struct zone *zone, unsigned int order)
668 {
669         struct contig_page_info info;
670 
671         fill_contig_page_info(zone, order, &info);
672         return __fragmentation_index(order, &info);
673 }
674 #endif
675 
676 #if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || defined(CONFIG_NUMA)
677 #ifdef CONFIG_ZONE_DMA
678 #define TEXT_FOR_DMA(xx) xx "_dma",
679 #else
680 #define TEXT_FOR_DMA(xx)
681 #endif
682 
683 #ifdef CONFIG_ZONE_DMA32
684 #define TEXT_FOR_DMA32(xx) xx "_dma32",
685 #else
686 #define TEXT_FOR_DMA32(xx)
687 #endif
688 
689 #ifdef CONFIG_HIGHMEM
690 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
691 #else
692 #define TEXT_FOR_HIGHMEM(xx)
693 #endif
694 
695 #define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
696                                         TEXT_FOR_HIGHMEM(xx) xx "_movable",
697 
698 const char * const vmstat_text[] = {
699         /* enum zone_stat_item countes */
700         "nr_free_pages",
701         "nr_alloc_batch",
702         "nr_inactive_anon",
703         "nr_active_anon",
704         "nr_inactive_file",
705         "nr_active_file",
706         "nr_unevictable",
707         "nr_mlock",
708         "nr_anon_pages",
709         "nr_mapped",
710         "nr_file_pages",
711         "nr_dirty",
712         "nr_writeback",
713         "nr_slab_reclaimable",
714         "nr_slab_unreclaimable",
715         "nr_page_table_pages",
716         "nr_kernel_stack",
717         "nr_unstable",
718         "nr_bounce",
719         "nr_vmscan_write",
720         "nr_vmscan_immediate_reclaim",
721         "nr_writeback_temp",
722         "nr_isolated_anon",
723         "nr_isolated_file",
724         "nr_shmem",
725         "nr_dirtied",
726         "nr_written",
727         "nr_pages_scanned",
728 
729 #ifdef CONFIG_NUMA
730         "numa_hit",
731         "numa_miss",
732         "numa_foreign",
733         "numa_interleave",
734         "numa_local",
735         "numa_other",
736 #endif
737         "workingset_refault",
738         "workingset_activate",
739         "workingset_nodereclaim",
740         "nr_anon_transparent_hugepages",
741         "nr_free_cma",
742 
743         /* enum writeback_stat_item counters */
744         "nr_dirty_threshold",
745         "nr_dirty_background_threshold",
746 
747 #ifdef CONFIG_VM_EVENT_COUNTERS
748         /* enum vm_event_item counters */
749         "pgpgin",
750         "pgpgout",
751         "pswpin",
752         "pswpout",
753 
754         TEXTS_FOR_ZONES("pgalloc")
755 
756         "pgfree",
757         "pgactivate",
758         "pgdeactivate",
759 
760         "pgfault",
761         "pgmajfault",
762 
763         TEXTS_FOR_ZONES("pgrefill")
764         TEXTS_FOR_ZONES("pgsteal_kswapd")
765         TEXTS_FOR_ZONES("pgsteal_direct")
766         TEXTS_FOR_ZONES("pgscan_kswapd")
767         TEXTS_FOR_ZONES("pgscan_direct")
768         "pgscan_direct_throttle",
769 
770 #ifdef CONFIG_NUMA
771         "zone_reclaim_failed",
772 #endif
773         "pginodesteal",
774         "slabs_scanned",
775         "kswapd_inodesteal",
776         "kswapd_low_wmark_hit_quickly",
777         "kswapd_high_wmark_hit_quickly",
778         "pageoutrun",
779         "allocstall",
780 
781         "pgrotated",
782 
783         "drop_pagecache",
784         "drop_slab",
785 
786 #ifdef CONFIG_NUMA_BALANCING
787         "numa_pte_updates",
788         "numa_huge_pte_updates",
789         "numa_hint_faults",
790         "numa_hint_faults_local",
791         "numa_pages_migrated",
792 #endif
793 #ifdef CONFIG_MIGRATION
794         "pgmigrate_success",
795         "pgmigrate_fail",
796 #endif
797 #ifdef CONFIG_COMPACTION
798         "compact_migrate_scanned",
799         "compact_free_scanned",
800         "compact_isolated",
801         "compact_stall",
802         "compact_fail",
803         "compact_success",
804 #endif
805 
806 #ifdef CONFIG_HUGETLB_PAGE
807         "htlb_buddy_alloc_success",
808         "htlb_buddy_alloc_fail",
809 #endif
810         "unevictable_pgs_culled",
811         "unevictable_pgs_scanned",
812         "unevictable_pgs_rescued",
813         "unevictable_pgs_mlocked",
814         "unevictable_pgs_munlocked",
815         "unevictable_pgs_cleared",
816         "unevictable_pgs_stranded",
817 
818 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
819         "thp_fault_alloc",
820         "thp_fault_fallback",
821         "thp_collapse_alloc",
822         "thp_collapse_alloc_failed",
823         "thp_split",
824         "thp_zero_page_alloc",
825         "thp_zero_page_alloc_failed",
826 #endif
827 #ifdef CONFIG_MEMORY_BALLOON
828         "balloon_inflate",
829         "balloon_deflate",
830 #ifdef CONFIG_BALLOON_COMPACTION
831         "balloon_migrate",
832 #endif
833 #endif /* CONFIG_MEMORY_BALLOON */
834 #ifdef CONFIG_DEBUG_TLBFLUSH
835 #ifdef CONFIG_SMP
836         "nr_tlb_remote_flush",
837         "nr_tlb_remote_flush_received",
838 #endif /* CONFIG_SMP */
839         "nr_tlb_local_flush_all",
840         "nr_tlb_local_flush_one",
841 #endif /* CONFIG_DEBUG_TLBFLUSH */
842 
843 #ifdef CONFIG_DEBUG_VM_VMACACHE
844         "vmacache_find_calls",
845         "vmacache_find_hits",
846         "vmacache_full_flushes",
847 #endif
848 #endif /* CONFIG_VM_EVENTS_COUNTERS */
849 };
850 #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
851 
852 
853 #if (defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)) || \
854      defined(CONFIG_PROC_FS)
855 static void *frag_start(struct seq_file *m, loff_t *pos)
856 {
857         pg_data_t *pgdat;
858         loff_t node = *pos;
859 
860         for (pgdat = first_online_pgdat();
861              pgdat && node;
862              pgdat = next_online_pgdat(pgdat))
863                 --node;
864 
865         return pgdat;
866 }
867 
868 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
869 {
870         pg_data_t *pgdat = (pg_data_t *)arg;
871 
872         (*pos)++;
873         return next_online_pgdat(pgdat);
874 }
875 
876 static void frag_stop(struct seq_file *m, void *arg)
877 {
878 }
879 
880 /* Walk all the zones in a node and print using a callback */
881 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
882                 void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
883 {
884         struct zone *zone;
885         struct zone *node_zones = pgdat->node_zones;
886         unsigned long flags;
887 
888         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
889                 if (!populated_zone(zone))
890                         continue;
891 
892                 spin_lock_irqsave(&zone->lock, flags);
893                 print(m, pgdat, zone);
894                 spin_unlock_irqrestore(&zone->lock, flags);
895         }
896 }
897 #endif
898 
899 #ifdef CONFIG_PROC_FS
900 static char * const migratetype_names[MIGRATE_TYPES] = {
901         "Unmovable",
902         "Reclaimable",
903         "Movable",
904         "Reserve",
905 #ifdef CONFIG_CMA
906         "CMA",
907 #endif
908 #ifdef CONFIG_MEMORY_ISOLATION
909         "Isolate",
910 #endif
911 };
912 
913 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
914                                                 struct zone *zone)
915 {
916         int order;
917 
918         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
919         for (order = 0; order < MAX_ORDER; ++order)
920                 seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
921         seq_putc(m, '\n');
922 }
923 
924 /*
925  * This walks the free areas for each zone.
926  */
927 static int frag_show(struct seq_file *m, void *arg)
928 {
929         pg_data_t *pgdat = (pg_data_t *)arg;
930         walk_zones_in_node(m, pgdat, frag_show_print);
931         return 0;
932 }
933 
934 static void pagetypeinfo_showfree_print(struct seq_file *m,
935                                         pg_data_t *pgdat, struct zone *zone)
936 {
937         int order, mtype;
938 
939         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
940                 seq_printf(m, "Node %4d, zone %8s, type %12s ",
941                                         pgdat->node_id,
942                                         zone->name,
943                                         migratetype_names[mtype]);
944                 for (order = 0; order < MAX_ORDER; ++order) {
945                         unsigned long freecount = 0;
946                         struct free_area *area;
947                         struct list_head *curr;
948 
949                         area = &(zone->free_area[order]);
950 
951                         list_for_each(curr, &area->free_list[mtype])
952                                 freecount++;
953                         seq_printf(m, "%6lu ", freecount);
954                 }
955                 seq_putc(m, '\n');
956         }
957 }
958 
959 /* Print out the free pages at each order for each migatetype */
960 static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
961 {
962         int order;
963         pg_data_t *pgdat = (pg_data_t *)arg;
964 
965         /* Print header */
966         seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
967         for (order = 0; order < MAX_ORDER; ++order)
968                 seq_printf(m, "%6d ", order);
969         seq_putc(m, '\n');
970 
971         walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
972 
973         return 0;
974 }
975 
976 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
977                                         pg_data_t *pgdat, struct zone *zone)
978 {
979         int mtype;
980         unsigned long pfn;
981         unsigned long start_pfn = zone->zone_start_pfn;
982         unsigned long end_pfn = zone_end_pfn(zone);
983         unsigned long count[MIGRATE_TYPES] = { 0, };
984 
985         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
986                 struct page *page;
987 
988                 if (!pfn_valid(pfn))
989                         continue;
990 
991                 page = pfn_to_page(pfn);
992 
993                 /* Watch for unexpected holes punched in the memmap */
994                 if (!memmap_valid_within(pfn, page, zone))
995                         continue;
996 
997                 mtype = get_pageblock_migratetype(page);
998 
999                 if (mtype < MIGRATE_TYPES)
1000                         count[mtype]++;
1001         }
1002 
1003         /* Print counts */
1004         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
1005         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1006                 seq_printf(m, "%12lu ", count[mtype]);
1007         seq_putc(m, '\n');
1008 }
1009 
1010 /* Print out the free pages at each order for each migratetype */
1011 static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
1012 {
1013         int mtype;
1014         pg_data_t *pgdat = (pg_data_t *)arg;
1015 
1016         seq_printf(m, "\n%-23s", "Number of blocks type ");
1017         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1018                 seq_printf(m, "%12s ", migratetype_names[mtype]);
1019         seq_putc(m, '\n');
1020         walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
1021 
1022         return 0;
1023 }
1024 
1025 #ifdef CONFIG_PAGE_OWNER
1026 static void pagetypeinfo_showmixedcount_print(struct seq_file *m,
1027                                                         pg_data_t *pgdat,
1028                                                         struct zone *zone)
1029 {
1030         struct page *page;
1031         struct page_ext *page_ext;
1032         unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
1033         unsigned long end_pfn = pfn + zone->spanned_pages;
1034         unsigned long count[MIGRATE_TYPES] = { 0, };
1035         int pageblock_mt, page_mt;
1036         int i;
1037 
1038         /* Scan block by block. First and last block may be incomplete */
1039         pfn = zone->zone_start_pfn;
1040 
1041         /*
1042          * Walk the zone in pageblock_nr_pages steps. If a page block spans
1043          * a zone boundary, it will be double counted between zones. This does
1044          * not matter as the mixed block count will still be correct
1045          */
1046         for (; pfn < end_pfn; ) {
1047                 if (!pfn_valid(pfn)) {
1048                         pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
1049                         continue;
1050                 }
1051 
1052                 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
1053                 block_end_pfn = min(block_end_pfn, end_pfn);
1054 
1055                 page = pfn_to_page(pfn);
1056                 pageblock_mt = get_pfnblock_migratetype(page, pfn);
1057 
1058                 for (; pfn < block_end_pfn; pfn++) {
1059                         if (!pfn_valid_within(pfn))
1060                                 continue;
1061 
1062                         page = pfn_to_page(pfn);
1063                         if (PageBuddy(page)) {
1064                                 pfn += (1UL << page_order(page)) - 1;
1065                                 continue;
1066                         }
1067 
1068                         if (PageReserved(page))
1069                                 continue;
1070 
1071                         page_ext = lookup_page_ext(page);
1072 
1073                         if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
1074                                 continue;
1075 
1076                         page_mt = gfpflags_to_migratetype(page_ext->gfp_mask);
1077                         if (pageblock_mt != page_mt) {
1078                                 if (is_migrate_cma(pageblock_mt))
1079                                         count[MIGRATE_MOVABLE]++;
1080                                 else
1081                                         count[pageblock_mt]++;
1082 
1083                                 pfn = block_end_pfn;
1084                                 break;
1085                         }
1086                         pfn += (1UL << page_ext->order) - 1;
1087                 }
1088         }
1089 
1090         /* Print counts */
1091         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
1092         for (i = 0; i < MIGRATE_TYPES; i++)
1093                 seq_printf(m, "%12lu ", count[i]);
1094         seq_putc(m, '\n');
1095 }
1096 #endif /* CONFIG_PAGE_OWNER */
1097 
1098 /*
1099  * Print out the number of pageblocks for each migratetype that contain pages
1100  * of other types. This gives an indication of how well fallbacks are being
1101  * contained by rmqueue_fallback(). It requires information from PAGE_OWNER
1102  * to determine what is going on
1103  */
1104 static void pagetypeinfo_showmixedcount(struct seq_file *m, pg_data_t *pgdat)
1105 {
1106 #ifdef CONFIG_PAGE_OWNER
1107         int mtype;
1108 
1109         if (!page_owner_inited)
1110                 return;
1111 
1112         drain_all_pages(NULL);
1113 
1114         seq_printf(m, "\n%-23s", "Number of mixed blocks ");
1115         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1116                 seq_printf(m, "%12s ", migratetype_names[mtype]);
1117         seq_putc(m, '\n');
1118 
1119         walk_zones_in_node(m, pgdat, pagetypeinfo_showmixedcount_print);
1120 #endif /* CONFIG_PAGE_OWNER */
1121 }
1122 
1123 /*
1124  * This prints out statistics in relation to grouping pages by mobility.
1125  * It is expensive to collect so do not constantly read the file.
1126  */
1127 static int pagetypeinfo_show(struct seq_file *m, void *arg)
1128 {
1129         pg_data_t *pgdat = (pg_data_t *)arg;
1130 
1131         /* check memoryless node */
1132         if (!node_state(pgdat->node_id, N_MEMORY))
1133                 return 0;
1134 
1135         seq_printf(m, "Page block order: %d\n", pageblock_order);
1136         seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
1137         seq_putc(m, '\n');
1138         pagetypeinfo_showfree(m, pgdat);
1139         pagetypeinfo_showblockcount(m, pgdat);
1140         pagetypeinfo_showmixedcount(m, pgdat);
1141 
1142         return 0;
1143 }
1144 
1145 static const struct seq_operations fragmentation_op = {
1146         .start  = frag_start,
1147         .next   = frag_next,
1148         .stop   = frag_stop,
1149         .show   = frag_show,
1150 };
1151 
1152 static int fragmentation_open(struct inode *inode, struct file *file)
1153 {
1154         return seq_open(file, &fragmentation_op);
1155 }
1156 
1157 static const struct file_operations fragmentation_file_operations = {
1158         .open           = fragmentation_open,
1159         .read           = seq_read,
1160         .llseek         = seq_lseek,
1161         .release        = seq_release,
1162 };
1163 
1164 static const struct seq_operations pagetypeinfo_op = {
1165         .start  = frag_start,
1166         .next   = frag_next,
1167         .stop   = frag_stop,
1168         .show   = pagetypeinfo_show,
1169 };
1170 
1171 static int pagetypeinfo_open(struct inode *inode, struct file *file)
1172 {
1173         return seq_open(file, &pagetypeinfo_op);
1174 }
1175 
1176 static const struct file_operations pagetypeinfo_file_ops = {
1177         .open           = pagetypeinfo_open,
1178         .read           = seq_read,
1179         .llseek         = seq_lseek,
1180         .release        = seq_release,
1181 };
1182 
1183 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
1184                                                         struct zone *zone)
1185 {
1186         int i;
1187         seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
1188         seq_printf(m,
1189                    "\n  pages free     %lu"
1190                    "\n        min      %lu"
1191                    "\n        low      %lu"
1192                    "\n        high     %lu"
1193                    "\n        scanned  %lu"
1194                    "\n        spanned  %lu"
1195                    "\n        present  %lu"
1196                    "\n        managed  %lu",
1197                    zone_page_state(zone, NR_FREE_PAGES),
1198                    min_wmark_pages(zone),
1199                    low_wmark_pages(zone),
1200                    high_wmark_pages(zone),
1201                    zone_page_state(zone, NR_PAGES_SCANNED),
1202                    zone->spanned_pages,
1203                    zone->present_pages,
1204                    zone->managed_pages);
1205 
1206         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1207                 seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
1208                                 zone_page_state(zone, i));
1209 
1210         seq_printf(m,
1211                    "\n        protection: (%ld",
1212                    zone->lowmem_reserve[0]);
1213         for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
1214                 seq_printf(m, ", %ld", zone->lowmem_reserve[i]);
1215         seq_printf(m,
1216                    ")"
1217                    "\n  pagesets");
1218         for_each_online_cpu(i) {
1219                 struct per_cpu_pageset *pageset;
1220 
1221                 pageset = per_cpu_ptr(zone->pageset, i);
1222                 seq_printf(m,
1223                            "\n    cpu: %i"
1224                            "\n              count: %i"
1225                            "\n              high:  %i"
1226                            "\n              batch: %i",
1227                            i,
1228                            pageset->pcp.count,
1229                            pageset->pcp.high,
1230                            pageset->pcp.batch);
1231 #ifdef CONFIG_SMP
1232                 seq_printf(m, "\n  vm stats threshold: %d",
1233                                 pageset->stat_threshold);
1234 #endif
1235         }
1236         seq_printf(m,
1237                    "\n  all_unreclaimable: %u"
1238                    "\n  start_pfn:         %lu"
1239                    "\n  inactive_ratio:    %u",
1240                    !zone_reclaimable(zone),
1241                    zone->zone_start_pfn,
1242                    zone->inactive_ratio);
1243         seq_putc(m, '\n');
1244 }
1245 
1246 /*
1247  * Output information about zones in @pgdat.
1248  */
1249 static int zoneinfo_show(struct seq_file *m, void *arg)
1250 {
1251         pg_data_t *pgdat = (pg_data_t *)arg;
1252         walk_zones_in_node(m, pgdat, zoneinfo_show_print);
1253         return 0;
1254 }
1255 
1256 static const struct seq_operations zoneinfo_op = {
1257         .start  = frag_start, /* iterate over all zones. The same as in
1258                                * fragmentation. */
1259         .next   = frag_next,
1260         .stop   = frag_stop,
1261         .show   = zoneinfo_show,
1262 };
1263 
1264 static int zoneinfo_open(struct inode *inode, struct file *file)
1265 {
1266         return seq_open(file, &zoneinfo_op);
1267 }
1268 
1269 static const struct file_operations proc_zoneinfo_file_operations = {
1270         .open           = zoneinfo_open,
1271         .read           = seq_read,
1272         .llseek         = seq_lseek,
1273         .release        = seq_release,
1274 };
1275 
1276 enum writeback_stat_item {
1277         NR_DIRTY_THRESHOLD,
1278         NR_DIRTY_BG_THRESHOLD,
1279         NR_VM_WRITEBACK_STAT_ITEMS,
1280 };
1281 
1282 static void *vmstat_start(struct seq_file *m, loff_t *pos)
1283 {
1284         unsigned long *v;
1285         int i, stat_items_size;
1286 
1287         if (*pos >= ARRAY_SIZE(vmstat_text))
1288                 return NULL;
1289         stat_items_size = NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long) +
1290                           NR_VM_WRITEBACK_STAT_ITEMS * sizeof(unsigned long);
1291 
1292 #ifdef CONFIG_VM_EVENT_COUNTERS
1293         stat_items_size += sizeof(struct vm_event_state);
1294 #endif
1295 
1296         v = kmalloc(stat_items_size, GFP_KERNEL);
1297         m->private = v;
1298         if (!v)
1299                 return ERR_PTR(-ENOMEM);
1300         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1301                 v[i] = global_page_state(i);
1302         v += NR_VM_ZONE_STAT_ITEMS;
1303 
1304         global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1305                             v + NR_DIRTY_THRESHOLD);
1306         v += NR_VM_WRITEBACK_STAT_ITEMS;
1307 
1308 #ifdef CONFIG_VM_EVENT_COUNTERS
1309         all_vm_events(v);
1310         v[PGPGIN] /= 2;         /* sectors -> kbytes */
1311         v[PGPGOUT] /= 2;
1312 #endif
1313         return (unsigned long *)m->private + *pos;
1314 }
1315 
1316 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1317 {
1318         (*pos)++;
1319         if (*pos >= ARRAY_SIZE(vmstat_text))
1320                 return NULL;
1321         return (unsigned long *)m->private + *pos;
1322 }
1323 
1324 static int vmstat_show(struct seq_file *m, void *arg)
1325 {
1326         unsigned long *l = arg;
1327         unsigned long off = l - (unsigned long *)m->private;
1328 
1329         seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
1330         return 0;
1331 }
1332 
1333 static void vmstat_stop(struct seq_file *m, void *arg)
1334 {
1335         kfree(m->private);
1336         m->private = NULL;
1337 }
1338 
1339 static const struct seq_operations vmstat_op = {
1340         .start  = vmstat_start,
1341         .next   = vmstat_next,
1342         .stop   = vmstat_stop,
1343         .show   = vmstat_show,
1344 };
1345 
1346 static int vmstat_open(struct inode *inode, struct file *file)
1347 {
1348         return seq_open(file, &vmstat_op);
1349 }
1350 
1351 static const struct file_operations proc_vmstat_file_operations = {
1352         .open           = vmstat_open,
1353         .read           = seq_read,
1354         .llseek         = seq_lseek,
1355         .release        = seq_release,
1356 };
1357 #endif /* CONFIG_PROC_FS */
1358 
1359 #ifdef CONFIG_SMP
1360 static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1361 int sysctl_stat_interval __read_mostly = HZ;
1362 static cpumask_var_t cpu_stat_off;
1363 
1364 static void vmstat_update(struct work_struct *w)
1365 {
1366         if (refresh_cpu_vm_stats())
1367                 /*
1368                  * Counters were updated so we expect more updates
1369                  * to occur in the future. Keep on running the
1370                  * update worker thread.
1371                  */
1372                 schedule_delayed_work(this_cpu_ptr(&vmstat_work),
1373                         round_jiffies_relative(sysctl_stat_interval));
1374         else {
1375                 /*
1376                  * We did not update any counters so the app may be in
1377                  * a mode where it does not cause counter updates.
1378                  * We may be uselessly running vmstat_update.
1379                  * Defer the checking for differentials to the
1380                  * shepherd thread on a different processor.
1381                  */
1382                 int r;
1383                 /*
1384                  * Shepherd work thread does not race since it never
1385                  * changes the bit if its zero but the cpu
1386                  * online / off line code may race if
1387                  * worker threads are still allowed during
1388                  * shutdown / startup.
1389                  */
1390                 r = cpumask_test_and_set_cpu(smp_processor_id(),
1391                         cpu_stat_off);
1392                 VM_BUG_ON(r);
1393         }
1394 }
1395 
1396 /*
1397  * Check if the diffs for a certain cpu indicate that
1398  * an update is needed.
1399  */
1400 static bool need_update(int cpu)
1401 {
1402         struct zone *zone;
1403 
1404         for_each_populated_zone(zone) {
1405                 struct per_cpu_pageset *p = per_cpu_ptr(zone->pageset, cpu);
1406 
1407                 BUILD_BUG_ON(sizeof(p->vm_stat_diff[0]) != 1);
1408                 /*
1409                  * The fast way of checking if there are any vmstat diffs.
1410                  * This works because the diffs are byte sized items.
1411                  */
1412                 if (memchr_inv(p->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS))
1413                         return true;
1414 
1415         }
1416         return false;
1417 }
1418 
1419 
1420 /*
1421  * Shepherd worker thread that checks the
1422  * differentials of processors that have their worker
1423  * threads for vm statistics updates disabled because of
1424  * inactivity.
1425  */
1426 static void vmstat_shepherd(struct work_struct *w);
1427 
1428 static DECLARE_DELAYED_WORK(shepherd, vmstat_shepherd);
1429 
1430 static void vmstat_shepherd(struct work_struct *w)
1431 {
1432         int cpu;
1433 
1434         get_online_cpus();
1435         /* Check processors whose vmstat worker threads have been disabled */
1436         for_each_cpu(cpu, cpu_stat_off)
1437                 if (need_update(cpu) &&
1438                         cpumask_test_and_clear_cpu(cpu, cpu_stat_off))
1439 
1440                         schedule_delayed_work_on(cpu,
1441                                 &per_cpu(vmstat_work, cpu), 0);
1442 
1443         put_online_cpus();
1444 
1445         schedule_delayed_work(&shepherd,
1446                 round_jiffies_relative(sysctl_stat_interval));
1447 
1448 }
1449 
1450 static void __init start_shepherd_timer(void)
1451 {
1452         int cpu;
1453 
1454         for_each_possible_cpu(cpu)
1455                 INIT_DELAYED_WORK(per_cpu_ptr(&vmstat_work, cpu),
1456                         vmstat_update);
1457 
1458         if (!alloc_cpumask_var(&cpu_stat_off, GFP_KERNEL))
1459                 BUG();
1460         cpumask_copy(cpu_stat_off, cpu_online_mask);
1461 
1462         schedule_delayed_work(&shepherd,
1463                 round_jiffies_relative(sysctl_stat_interval));
1464 }
1465 
1466 static void vmstat_cpu_dead(int node)
1467 {
1468         int cpu;
1469 
1470         get_online_cpus();
1471         for_each_online_cpu(cpu)
1472                 if (cpu_to_node(cpu) == node)
1473                         goto end;
1474 
1475         node_clear_state(node, N_CPU);
1476 end:
1477         put_online_cpus();
1478 }
1479 
1480 /*
1481  * Use the cpu notifier to insure that the thresholds are recalculated
1482  * when necessary.
1483  */
1484 static int vmstat_cpuup_callback(struct notifier_block *nfb,
1485                 unsigned long action,
1486                 void *hcpu)
1487 {
1488         long cpu = (long)hcpu;
1489 
1490         switch (action) {
1491         case CPU_ONLINE:
1492         case CPU_ONLINE_FROZEN:
1493                 refresh_zone_stat_thresholds();
1494                 node_set_state(cpu_to_node(cpu), N_CPU);
1495                 cpumask_set_cpu(cpu, cpu_stat_off);
1496                 break;
1497         case CPU_DOWN_PREPARE:
1498         case CPU_DOWN_PREPARE_FROZEN:
1499                 cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
1500                 cpumask_clear_cpu(cpu, cpu_stat_off);
1501                 break;
1502         case CPU_DOWN_FAILED:
1503         case CPU_DOWN_FAILED_FROZEN:
1504                 cpumask_set_cpu(cpu, cpu_stat_off);
1505                 break;
1506         case CPU_DEAD:
1507         case CPU_DEAD_FROZEN:
1508                 refresh_zone_stat_thresholds();
1509                 vmstat_cpu_dead(cpu_to_node(cpu));
1510                 break;
1511         default:
1512                 break;
1513         }
1514         return NOTIFY_OK;
1515 }
1516 
1517 static struct notifier_block vmstat_notifier =
1518         { &vmstat_cpuup_callback, NULL, 0 };
1519 #endif
1520 
1521 static int __init setup_vmstat(void)
1522 {
1523 #ifdef CONFIG_SMP
1524         cpu_notifier_register_begin();
1525         __register_cpu_notifier(&vmstat_notifier);
1526 
1527         start_shepherd_timer();
1528         cpu_notifier_register_done();
1529 #endif
1530 #ifdef CONFIG_PROC_FS
1531         proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
1532         proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
1533         proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
1534         proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
1535 #endif
1536         return 0;
1537 }
1538 module_init(setup_vmstat)
1539 
1540 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
1541 
1542 /*
1543  * Return an index indicating how much of the available free memory is
1544  * unusable for an allocation of the requested size.
1545  */
1546 static int unusable_free_index(unsigned int order,
1547                                 struct contig_page_info *info)
1548 {
1549         /* No free memory is interpreted as all free memory is unusable */
1550         if (info->free_pages == 0)
1551                 return 1000;
1552 
1553         /*
1554          * Index should be a value between 0 and 1. Return a value to 3
1555          * decimal places.
1556          *
1557          * 0 => no fragmentation
1558          * 1 => high fragmentation
1559          */
1560         return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
1561 
1562 }
1563 
1564 static void unusable_show_print(struct seq_file *m,
1565                                         pg_data_t *pgdat, struct zone *zone)
1566 {
1567         unsigned int order;
1568         int index;
1569         struct contig_page_info info;
1570 
1571         seq_printf(m, "Node %d, zone %8s ",
1572                                 pgdat->node_id,
1573                                 zone->name);
1574         for (order = 0; order < MAX_ORDER; ++order) {
1575                 fill_contig_page_info(zone, order, &info);
1576                 index = unusable_free_index(order, &info);
1577                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1578         }
1579 
1580         seq_putc(m, '\n');
1581 }
1582 
1583 /*
1584  * Display unusable free space index
1585  *
1586  * The unusable free space index measures how much of the available free
1587  * memory cannot be used to satisfy an allocation of a given size and is a
1588  * value between 0 and 1. The higher the value, the more of free memory is
1589  * unusable and by implication, the worse the external fragmentation is. This
1590  * can be expressed as a percentage by multiplying by 100.
1591  */
1592 static int unusable_show(struct seq_file *m, void *arg)
1593 {
1594         pg_data_t *pgdat = (pg_data_t *)arg;
1595 
1596         /* check memoryless node */
1597         if (!node_state(pgdat->node_id, N_MEMORY))
1598                 return 0;
1599 
1600         walk_zones_in_node(m, pgdat, unusable_show_print);
1601 
1602         return 0;
1603 }
1604 
1605 static const struct seq_operations unusable_op = {
1606         .start  = frag_start,
1607         .next   = frag_next,
1608         .stop   = frag_stop,
1609         .show   = unusable_show,
1610 };
1611 
1612 static int unusable_open(struct inode *inode, struct file *file)
1613 {
1614         return seq_open(file, &unusable_op);
1615 }
1616 
1617 static const struct file_operations unusable_file_ops = {
1618         .open           = unusable_open,
1619         .read           = seq_read,
1620         .llseek         = seq_lseek,
1621         .release        = seq_release,
1622 };
1623 
1624 static void extfrag_show_print(struct seq_file *m,
1625                                         pg_data_t *pgdat, struct zone *zone)
1626 {
1627         unsigned int order;
1628         int index;
1629 
1630         /* Alloc on stack as interrupts are disabled for zone walk */
1631         struct contig_page_info info;
1632 
1633         seq_printf(m, "Node %d, zone %8s ",
1634                                 pgdat->node_id,
1635                                 zone->name);
1636         for (order = 0; order < MAX_ORDER; ++order) {
1637                 fill_contig_page_info(zone, order, &info);
1638                 index = __fragmentation_index(order, &info);
1639                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1640         }
1641 
1642         seq_putc(m, '\n');
1643 }
1644 
1645 /*
1646  * Display fragmentation index for orders that allocations would fail for
1647  */
1648 static int extfrag_show(struct seq_file *m, void *arg)
1649 {
1650         pg_data_t *pgdat = (pg_data_t *)arg;
1651 
1652         walk_zones_in_node(m, pgdat, extfrag_show_print);
1653 
1654         return 0;
1655 }
1656 
1657 static const struct seq_operations extfrag_op = {
1658         .start  = frag_start,
1659         .next   = frag_next,
1660         .stop   = frag_stop,
1661         .show   = extfrag_show,
1662 };
1663 
1664 static int extfrag_open(struct inode *inode, struct file *file)
1665 {
1666         return seq_open(file, &extfrag_op);
1667 }
1668 
1669 static const struct file_operations extfrag_file_ops = {
1670         .open           = extfrag_open,
1671         .read           = seq_read,
1672         .llseek         = seq_lseek,
1673         .release        = seq_release,
1674 };
1675 
1676 static int __init extfrag_debug_init(void)
1677 {
1678         struct dentry *extfrag_debug_root;
1679 
1680         extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
1681         if (!extfrag_debug_root)
1682                 return -ENOMEM;
1683 
1684         if (!debugfs_create_file("unusable_index", 0444,
1685                         extfrag_debug_root, NULL, &unusable_file_ops))
1686                 goto fail;
1687 
1688         if (!debugfs_create_file("extfrag_index", 0444,
1689                         extfrag_debug_root, NULL, &extfrag_file_ops))
1690                 goto fail;
1691 
1692         return 0;
1693 fail:
1694         debugfs_remove_recursive(extfrag_debug_root);
1695         return -ENOMEM;
1696 }
1697 
1698 module_init(extfrag_debug_init);
1699 #endif
1700 

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