include/linux/page_counter.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef _LINUX_PAGE_COUNTER_H
0003 #define _LINUX_PAGE_COUNTER_H
0004
0005 #include <linux/atomic.h>
0006 #include <linux/kernel.h>
0007 #include <asm/page.h>
0008
0009 struct page_counter {
0010     atomic_long_t usage;
0011     unsigned long min;
0012     unsigned long low;
0013     unsigned long high;
0014     unsigned long max;
0015
0016     /* effective memory.min and memory.min usage tracking */
0017     unsigned long emin;
0018     atomic_long_t min_usage;
0019     atomic_long_t children_min_usage;
0020
0021     /* effective memory.low and memory.low usage tracking */
0022     unsigned long elow;
0023     atomic_long_t low_usage;
0024     atomic_long_t children_low_usage;
0025
0026     /* legacy */
0027     unsigned long watermark;
0028     unsigned long failcnt;
0029
0030     /*
0031      * 'parent' is placed here to be far from 'usage' to reduce
0032      * cache false sharing, as 'usage' is written mostly while
0033      * parent is frequently read for cgroup's hierarchical
0034      * counting nature.
0035      */
0036     struct page_counter *parent;
0037 };
0038
0039 #if BITS_PER_LONG == 32
0040 #define PAGE_COUNTER_MAX LONG_MAX
0041 #else
0042 #define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
0043 #endif
0044
0045 static inline void page_counter_init(struct page_counter *counter,
0046                      struct page_counter *parent)
0047 {
0048     atomic_long_set(&counter->usage, 0);
0049     counter->max = PAGE_COUNTER_MAX;
0050     counter->parent = parent;
0051 }
0052
0053 static inline unsigned long page_counter_read(struct page_counter *counter)
0054 {
0055     return atomic_long_read(&counter->usage);
0056 }
0057
0058 void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
0059 void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
0060 bool page_counter_try_charge(struct page_counter *counter,
0061                  unsigned long nr_pages,
0062                  struct page_counter **fail);
0063 void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
0064 void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages);
0065 void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);
0066
0067 static inline void page_counter_set_high(struct page_counter *counter,
0068                      unsigned long nr_pages)
0069 {
0070     WRITE_ONCE(counter->high, nr_pages);
0071 }
0072
0073 int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
0074 int page_counter_memparse(const char *buf, const char *max,
0075               unsigned long *nr_pages);
0076
0077 static inline void page_counter_reset_watermark(struct page_counter *counter)
0078 {
0079     counter->watermark = page_counter_read(counter);
0080 }
0081
0082 #endif /* _LINUX_PAGE_COUNTER_H */