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 */
27 extern int percpu_counter_batch;
29 int percpu_counter_init(struct percpu_counter *fbc, s64 amount);
30 int percpu_counter_init_irq(struct percpu_counter *fbc, s64 amount);
31 void percpu_counter_destroy(struct percpu_counter *fbc);
32 void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
33 void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
34 s64 __percpu_counter_sum(struct percpu_counter *fbc);
36 static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
38 __percpu_counter_add(fbc, amount, percpu_counter_batch);
41 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
43 s64 ret = __percpu_counter_sum(fbc);
44 return ret < 0 ? 0 : ret;
47 static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
49 return __percpu_counter_sum(fbc);
52 static inline s64 percpu_counter_read(struct percpu_counter *fbc)
58 * It is possible for the percpu_counter_read() to return a small negative
59 * number for some counter which should never be negative.
62 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
66 barrier(); /* Prevent reloads of fbc->count */
74 struct percpu_counter {
78 static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
84 #define percpu_counter_init_irq percpu_counter_init
86 static inline void percpu_counter_destroy(struct percpu_counter *fbc)
90 static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
95 #define __percpu_counter_add(fbc, amount, batch) \
96 percpu_counter_add(fbc, amount)
99 percpu_counter_add(struct percpu_counter *fbc, s64 amount)
102 fbc->count += amount;
106 static inline s64 percpu_counter_read(struct percpu_counter *fbc)
111 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
116 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
118 return percpu_counter_read_positive(fbc);
121 static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
123 return percpu_counter_read(fbc);
126 #endif /* CONFIG_SMP */
128 static inline void percpu_counter_inc(struct percpu_counter *fbc)
130 percpu_counter_add(fbc, 1);
133 static inline void percpu_counter_dec(struct percpu_counter *fbc)
135 percpu_counter_add(fbc, -1);
138 static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
140 percpu_counter_add(fbc, -amount);
143 #endif /* _LINUX_PERCPU_COUNTER_H */