include/linux/page_counter.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_PAGE_COUNTER_H
   3 #define _LINUX_PAGE_COUNTER_H
   4
   5 #include <linux/atomic.h>
   6 #include <linux/kernel.h>
   7 #include <asm/page.h>
   8
   9 struct page_counter {
  10         atomic_long_t usage;
  11         unsigned long min;
  12         unsigned long low;
  13         unsigned long high;
  14         unsigned long max;
  15
  16         /* effective memory.min and memory.min usage tracking */
  17         unsigned long emin;
  18         atomic_long_t min_usage;
  19         atomic_long_t children_min_usage;
  20
  21         /* effective memory.low and memory.low usage tracking */
  22         unsigned long elow;
  23         atomic_long_t low_usage;
  24         atomic_long_t children_low_usage;
  25
  26         /* legacy */
  27         unsigned long watermark;
  28         unsigned long failcnt;
  29
  30         /*
  31          * 'parent' is placed here to be far from 'usage' to reduce
  32          * cache false sharing, as 'usage' is written mostly while
  33          * parent is frequently read for cgroup's hierarchical
  34          * counting nature.
  35          */
  36         struct page_counter *parent;
  37 };
  38
  39 #if BITS_PER_LONG == 32
  40 #define PAGE_COUNTER_MAX LONG_MAX
  41 #else
  42 #define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
  43 #endif
  44
  45 static inline void page_counter_init(struct page_counter *counter,
  46                                      struct page_counter *parent)
  47 {
  48         atomic_long_set(&counter->usage, 0);
  49         counter->max = PAGE_COUNTER_MAX;
  50         counter->parent = parent;
  51 }
  52
  53 static inline unsigned long page_counter_read(struct page_counter *counter)
  54 {
  55         return atomic_long_read(&counter->usage);
  56 }
  57
  58 void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
  59 void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
  60 bool page_counter_try_charge(struct page_counter *counter,
  61                              unsigned long nr_pages,
  62                              struct page_counter **fail);
  63 void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
  64 void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages);
  65 void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);
  66
  67 static inline void page_counter_set_high(struct page_counter *counter,
  68                                          unsigned long nr_pages)
  69 {
  70         WRITE_ONCE(counter->high, nr_pages);
  71 }
  72
  73 int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
  74 int page_counter_memparse(const char *buf, const char *max,
  75                           unsigned long *nr_pages);
  76
  77 static inline void page_counter_reset_watermark(struct page_counter *counter)
  78 {
  79         counter->watermark = page_counter_read(counter);
  80 }
  81
  82 #endif /* _LINUX_PAGE_COUNTER_H */