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/threads.h>
12 #include <linux/percpu.h>
13 #include <linux/types.h>
17 struct percpu_counter {
24 #define FBC_BATCH (NR_CPUS*2)
26 #define FBC_BATCH (NR_CPUS*4)
29 static inline void percpu_counter_init(struct percpu_counter *fbc, s64 amount)
31 spin_lock_init(&fbc->lock);
33 fbc->counters = alloc_percpu(s32);
36 static inline void percpu_counter_destroy(struct percpu_counter *fbc)
38 free_percpu(fbc->counters);
41 void percpu_counter_mod(struct percpu_counter *fbc, s32 amount);
42 s64 percpu_counter_sum(struct percpu_counter *fbc);
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)
80 percpu_counter_mod(struct percpu_counter *fbc, s32 amount)
87 static inline s64 percpu_counter_read(struct percpu_counter *fbc)
92 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
97 static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
99 return percpu_counter_read_positive(fbc);
102 #endif /* CONFIG_SMP */
104 static inline void percpu_counter_inc(struct percpu_counter *fbc)
106 percpu_counter_mod(fbc, 1);
109 static inline void percpu_counter_dec(struct percpu_counter *fbc)
111 percpu_counter_mod(fbc, -1);
114 #endif /* _LINUX_PERCPU_COUNTER_H */