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 */
24 s32 __percpu
*counters
;
27 extern int percpu_counter_batch
;
29 int __percpu_counter_init(struct percpu_counter
*fbc
, s64 amount
,
30 struct lock_class_key
*key
);
32 #define percpu_counter_init(fbc, value) \
34 static struct lock_class_key __key; \
36 __percpu_counter_init(fbc, value, &__key); \
39 void percpu_counter_destroy(struct percpu_counter
*fbc
);
40 void percpu_counter_set(struct percpu_counter
*fbc
, s64 amount
);
41 void __percpu_counter_add(struct percpu_counter
*fbc
, s64 amount
, s32 batch
);
42 s64
__percpu_counter_sum(struct percpu_counter
*fbc
);
44 static inline void percpu_counter_add(struct percpu_counter
*fbc
, s64 amount
)
46 __percpu_counter_add(fbc
, amount
, percpu_counter_batch
);
49 static inline s64
percpu_counter_sum_positive(struct percpu_counter
*fbc
)
51 s64 ret
= __percpu_counter_sum(fbc
);
52 return ret
< 0 ? 0 : ret
;
55 static inline s64
percpu_counter_sum(struct percpu_counter
*fbc
)
57 return __percpu_counter_sum(fbc
);
60 static inline s64
percpu_counter_read(struct percpu_counter
*fbc
)
66 * It is possible for the percpu_counter_read() to return a small negative
67 * number for some counter which should never be negative.
70 static inline s64
percpu_counter_read_positive(struct percpu_counter
*fbc
)
74 barrier(); /* Prevent reloads of fbc->count */
82 struct percpu_counter
{
86 static inline int percpu_counter_init(struct percpu_counter
*fbc
, s64 amount
)
92 static inline void percpu_counter_destroy(struct percpu_counter
*fbc
)
96 static inline void percpu_counter_set(struct percpu_counter
*fbc
, s64 amount
)
102 percpu_counter_add(struct percpu_counter
*fbc
, s64 amount
)
105 fbc
->count
+= amount
;
110 __percpu_counter_add(struct percpu_counter
*fbc
, s64 amount
, s32 batch
)
112 percpu_counter_add(fbc
, amount
);
115 static inline s64
percpu_counter_read(struct percpu_counter
*fbc
)
120 static inline s64
percpu_counter_read_positive(struct percpu_counter
*fbc
)
125 static inline s64
percpu_counter_sum_positive(struct percpu_counter
*fbc
)
127 return percpu_counter_read_positive(fbc
);
130 static inline s64
percpu_counter_sum(struct percpu_counter
*fbc
)
132 return percpu_counter_read(fbc
);
135 #endif /* CONFIG_SMP */
137 static inline void percpu_counter_inc(struct percpu_counter
*fbc
)
139 percpu_counter_add(fbc
, 1);
142 static inline void percpu_counter_dec(struct percpu_counter
*fbc
)
144 percpu_counter_add(fbc
, -1);
147 static inline void percpu_counter_sub(struct percpu_counter
*fbc
, s64 amount
)
149 percpu_counter_add(fbc
, -amount
);
152 #endif /* _LINUX_PERCPU_COUNTER_H */
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