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 void percpu_counter_init(struct percpu_counter *fbc, s64 amount);
34 void percpu_counter_destroy(struct percpu_counter *fbc);
35 void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
36 void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
37 s64 __percpu_counter_sum(struct percpu_counter *fbc);
39 static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
41 __percpu_counter_add(fbc, amount, FBC_BATCH);
44 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
46 s64 ret = __percpu_counter_sum(fbc);
47 return ret < 0 ? 0 : ret;
50 static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
52 return __percpu_counter_sum(fbc);
55 static inline s64 percpu_counter_read(struct percpu_counter *fbc)
61 * It is possible for the percpu_counter_read() to return a small negative
62 * number for some counter which should never be negative.
65 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
69 barrier(); /* Prevent reloads of fbc->count */
77 struct percpu_counter {
81 static inline void percpu_counter_init(struct percpu_counter *fbc, s64 amount)
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 */