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/cache.h>
   7 #include <linux/kernel.h>
   8 #include <asm/page.h>
   9
  10 struct page_counter {
  11         /*
  12          * Make sure 'usage' does not share cacheline with any other field. The
  13          * memcg->memory.usage is a hot member of struct mem_cgroup.
  14          */
  15         atomic_long_t usage;
  16         CACHELINE_PADDING(_pad1_);
  17
  18         /* effective memory.min and memory.min usage tracking */
  19         unsigned long emin;
  20         atomic_long_t min_usage;
  21         atomic_long_t children_min_usage;
  22
  23         /* effective memory.low and memory.low usage tracking */
  24         unsigned long elow;
  25         atomic_long_t low_usage;
  26         atomic_long_t children_low_usage;
  27
  28         unsigned long watermark;
  29         unsigned long failcnt;
  30
  31         /* Keep all the read most fields in a separete cacheline. */
  32         CACHELINE_PADDING(_pad2_);
  33
  34         unsigned long min;
  35         unsigned long low;
  36         unsigned long high;
  37         unsigned long max;
  38         struct page_counter *parent;
  39 } ____cacheline_internodealigned_in_smp;
  40
  41 #if BITS_PER_LONG == 32
  42 #define PAGE_COUNTER_MAX LONG_MAX
  43 #else
  44 #define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
  45 #endif
  46
  47 static inline void page_counter_init(struct page_counter *counter,
  48                                      struct page_counter *parent)
  49 {
  50         atomic_long_set(&counter->usage, 0);
  51         counter->max = PAGE_COUNTER_MAX;
  52         counter->parent = parent;
  53 }
  54
  55 static inline unsigned long page_counter_read(struct page_counter *counter)
  56 {
  57         return atomic_long_read(&counter->usage);
  58 }
  59
  60 void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
  61 void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
  62 bool page_counter_try_charge(struct page_counter *counter,
  63                              unsigned long nr_pages,
  64                              struct page_counter **fail);
  65 void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
  66 void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages);
  67 void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);
  68
  69 static inline void page_counter_set_high(struct page_counter *counter,
  70                                          unsigned long nr_pages)
  71 {
  72         WRITE_ONCE(counter->high, nr_pages);
  73 }
  74
  75 int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
  76 int page_counter_memparse(const char *buf, const char *max,
  77                           unsigned long *nr_pages);
  78
  79 static inline void page_counter_reset_watermark(struct page_counter *counter)
  80 {
  81         counter->watermark = page_counter_read(counter);
  82 }
  83
  84 #endif /* _LINUX_PAGE_COUNTER_H */