LXR linux/include/linux/page

   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
   9struct 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
  45static 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
  53static inline unsigned long page_counter_read(struct page_counter *counter)
  54{
  55        return atomic_long_read(&counter->usage);
  56}
  57
  58void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
  59void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
  60bool page_counter_try_charge(struct page_counter *counter,
  61                             unsigned long nr_pages,
  62                             struct page_counter **fail);
  63void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
  64void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages);
  65void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);
  66
  67static 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
  73int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
  74int page_counter_memparse(const char *buf, const char *max,
  75                          unsigned long *nr_pages);
  76
  77static 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 */
  83