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_positive(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_read(struct percpu_counter *fbc)
50 * It is possible for the percpu_counter_read() to return a small negative
51 * number for some counter which should never be negative.
54 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
58 barrier(); /* Prevent reloads of fbc->count */
66 struct percpu_counter {
70 static inline void percpu_counter_init(struct percpu_counter *fbc, s64 amount)
75 static inline void percpu_counter_destroy(struct percpu_counter *fbc)
79 static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
84 #define __percpu_counter_add(fbc, amount, batch) \
85 percpu_counter_add(fbc, amount)
88 percpu_counter_add(struct percpu_counter *fbc, s64 amount)
95 static inline s64 percpu_counter_read(struct percpu_counter *fbc)
100 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
105 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
107 return percpu_counter_read_positive(fbc);
110 #endif /* CONFIG_SMP */
112 static inline void percpu_counter_inc(struct percpu_counter *fbc)
114 percpu_counter_add(fbc, 1);
117 static inline void percpu_counter_dec(struct percpu_counter *fbc)
119 percpu_counter_add(fbc, -1);
122 static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
124 percpu_counter_add(fbc, -amount);
127 #endif /* _LINUX_PERCPU_COUNTER_H */