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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - include/linux/percpu_counter.h
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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>
15 #include <linux/gfp.h>
19 struct percpu_counter
{
22 #ifdef CONFIG_HOTPLUG_CPU
23 struct list_head list
; /* All percpu_counters are on a list */
25 s32 __percpu
*counters
;
28 extern int percpu_counter_batch
;
30 int __percpu_counter_init(struct percpu_counter
*fbc
, s64 amount
, gfp_t gfp
,
31 struct lock_class_key
*key
);
33 #define percpu_counter_init(fbc, value, gfp) \
35 static struct lock_class_key __key; \
37 __percpu_counter_init(fbc, value, gfp, &__key); \
40 void percpu_counter_destroy(struct percpu_counter
*fbc
);
41 void percpu_counter_set(struct percpu_counter
*fbc
, s64 amount
);
42 void percpu_counter_add_batch(struct percpu_counter
*fbc
, s64 amount
,
44 s64
__percpu_counter_sum(struct percpu_counter
*fbc
);
45 int __percpu_counter_compare(struct percpu_counter
*fbc
, s64 rhs
, s32 batch
);
47 static inline int percpu_counter_compare(struct percpu_counter
*fbc
, s64 rhs
)
49 return __percpu_counter_compare(fbc
, rhs
, percpu_counter_batch
);
52 static inline void percpu_counter_add(struct percpu_counter
*fbc
, s64 amount
)
54 percpu_counter_add_batch(fbc
, amount
, percpu_counter_batch
);
57 static inline s64
percpu_counter_sum_positive(struct percpu_counter
*fbc
)
59 s64 ret
= __percpu_counter_sum(fbc
);
60 return ret
< 0 ? 0 : ret
;
63 static inline s64
percpu_counter_sum(struct percpu_counter
*fbc
)
65 return __percpu_counter_sum(fbc
);
68 static inline s64
percpu_counter_read(struct percpu_counter
*fbc
)
74 * It is possible for the percpu_counter_read() to return a small negative
75 * number for some counter which should never be negative.
78 static inline s64
percpu_counter_read_positive(struct percpu_counter
*fbc
)
82 barrier(); /* Prevent reloads of fbc->count */
88 static inline int percpu_counter_initialized(struct percpu_counter
*fbc
)
90 return (fbc
->counters
!= NULL
);
93 #else /* !CONFIG_SMP */
95 struct percpu_counter
{
99 static inline int percpu_counter_init(struct percpu_counter
*fbc
, s64 amount
,
106 static inline void percpu_counter_destroy(struct percpu_counter
*fbc
)
110 static inline void percpu_counter_set(struct percpu_counter
*fbc
, s64 amount
)
115 static inline int percpu_counter_compare(struct percpu_counter
*fbc
, s64 rhs
)
117 if (fbc
->count
> rhs
)
119 else if (fbc
->count
< rhs
)
126 __percpu_counter_compare(struct percpu_counter
*fbc
, s64 rhs
, s32 batch
)
128 return percpu_counter_compare(fbc
, rhs
);
132 percpu_counter_add(struct percpu_counter
*fbc
, s64 amount
)
135 fbc
->count
+= amount
;
140 percpu_counter_add_batch(struct percpu_counter
*fbc
, s64 amount
, s32 batch
)
142 percpu_counter_add(fbc
, amount
);
145 static inline s64
percpu_counter_read(struct percpu_counter
*fbc
)
151 * percpu_counter is intended to track positive numbers. In the UP case the
152 * number should never be negative.
154 static inline s64
percpu_counter_read_positive(struct percpu_counter
*fbc
)
159 static inline s64
percpu_counter_sum_positive(struct percpu_counter
*fbc
)
161 return percpu_counter_read_positive(fbc
);
164 static inline s64
percpu_counter_sum(struct percpu_counter
*fbc
)
166 return percpu_counter_read(fbc
);
169 static inline int percpu_counter_initialized(struct percpu_counter
*fbc
)
174 #endif /* CONFIG_SMP */
176 static inline void percpu_counter_inc(struct percpu_counter
*fbc
)
178 percpu_counter_add(fbc
, 1);
181 static inline void percpu_counter_dec(struct percpu_counter
*fbc
)
183 percpu_counter_add(fbc
, -1);
186 static inline void percpu_counter_sub(struct percpu_counter
*fbc
, s64 amount
)
188 percpu_counter_add(fbc
, -amount
);
191 #endif /* _LINUX_PERCPU_COUNTER_H */