1 #ifndef _LINUX_PERCPU_COUNTER_H
2 #define _LINUX_PERCPU_COUNTER_H
4 * A simple "approximate counter" for use in ext2 and ext3 superblocks.
6 * WARNING: these things are HUGE. 4 kbytes per counter on 32-way P4.
9 #include <linux/spinlock.h>
10 #include <linux/smp.h>
11 #include <linux/list.h>
12 #include <linux/threads.h>
13 #include <linux/percpu.h>
14 #include <linux/types.h>
18 struct percpu_counter {
21 #ifdef CONFIG_HOTPLUG_CPU
22 struct list_head list; /* All percpu_counters are on a list */
28 #define FBC_BATCH (NR_CPUS*2)
30 #define FBC_BATCH (NR_CPUS*4)
33 int __percpu_counter_init(struct percpu_counter *fbc, s64 amount,
34 struct lock_class_key *key);
36 #define percpu_counter_init(fbc, value) \
38 static struct lock_class_key __key; \
40 __percpu_counter_init(fbc, value, &__key); \
43 void percpu_counter_destroy(struct percpu_counter *fbc);
44 void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
45 void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
46 s64 __percpu_counter_sum(struct percpu_counter *fbc);
48 static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
50 __percpu_counter_add(fbc, amount, FBC_BATCH);
53 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
55 s64 ret = __percpu_counter_sum(fbc);
56 return ret < 0 ? 0 : ret;
59 static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
61 return __percpu_counter_sum(fbc);
64 static inline s64 percpu_counter_read(struct percpu_counter *fbc)
70 * It is possible for the percpu_counter_read() to return a small negative
71 * number for some counter which should never be negative.
74 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
78 barrier(); /* Prevent reloads of fbc->count */
86 struct percpu_counter {
90 static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
96 static inline void percpu_counter_destroy(struct percpu_counter *fbc)
100 static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
105 #define __percpu_counter_add(fbc, amount, batch) \
106 percpu_counter_add(fbc, amount)
109 percpu_counter_add(struct percpu_counter *fbc, s64 amount)
112 fbc->count += amount;
116 static inline s64 percpu_counter_read(struct percpu_counter *fbc)
121 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
126 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
128 return percpu_counter_read_positive(fbc);
131 static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
133 return percpu_counter_read(fbc);
136 #endif /* CONFIG_SMP */
138 static inline void percpu_counter_inc(struct percpu_counter *fbc)
140 percpu_counter_add(fbc, 1);
143 static inline void percpu_counter_dec(struct percpu_counter *fbc)
145 percpu_counter_add(fbc, -1);
148 static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
150 percpu_counter_add(fbc, -amount);
153 #endif /* _LINUX_PERCPU_COUNTER_H */