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1da177e4 LT |
1 | #ifndef _LINUX_PERCPU_COUNTER_H |
2 | #define _LINUX_PERCPU_COUNTER_H | |
3 | /* | |
4 | * A simple "approximate counter" for use in ext2 and ext3 superblocks. | |
5 | * | |
6 | * WARNING: these things are HUGE. 4 kbytes per counter on 32-way P4. | |
7 | */ | |
8 | ||
1da177e4 LT |
9 | #include <linux/spinlock.h> |
10 | #include <linux/smp.h> | |
c67ad917 | 11 | #include <linux/list.h> |
1da177e4 LT |
12 | #include <linux/threads.h> |
13 | #include <linux/percpu.h> | |
0216bfcf | 14 | #include <linux/types.h> |
1da177e4 LT |
15 | |
16 | #ifdef CONFIG_SMP | |
17 | ||
18 | struct percpu_counter { | |
19 | spinlock_t lock; | |
0216bfcf | 20 | s64 count; |
c67ad917 AM |
21 | #ifdef CONFIG_HOTPLUG_CPU |
22 | struct list_head list; /* All percpu_counters are on a list */ | |
23 | #endif | |
0216bfcf | 24 | s32 *counters; |
1da177e4 LT |
25 | }; |
26 | ||
27 | #if NR_CPUS >= 16 | |
28 | #define FBC_BATCH (NR_CPUS*2) | |
29 | #else | |
30 | #define FBC_BATCH (NR_CPUS*4) | |
31 | #endif | |
32 | ||
c67ad917 AM |
33 | void percpu_counter_init(struct percpu_counter *fbc, s64 amount); |
34 | void percpu_counter_destroy(struct percpu_counter *fbc); | |
252e0ba6 | 35 | void __percpu_counter_add(struct percpu_counter *fbc, s32 amount, s32 batch); |
0216bfcf | 36 | s64 percpu_counter_sum(struct percpu_counter *fbc); |
1da177e4 | 37 | |
252e0ba6 PZ |
38 | static inline void percpu_counter_add(struct percpu_counter *fbc, s32 amount) |
39 | { | |
40 | __percpu_counter_add(fbc, amount, FBC_BATCH); | |
41 | } | |
42 | ||
0216bfcf | 43 | static inline s64 percpu_counter_read(struct percpu_counter *fbc) |
1da177e4 LT |
44 | { |
45 | return fbc->count; | |
46 | } | |
47 | ||
48 | /* | |
49 | * It is possible for the percpu_counter_read() to return a small negative | |
50 | * number for some counter which should never be negative. | |
0216bfcf | 51 | * |
1da177e4 | 52 | */ |
0216bfcf | 53 | static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc) |
1da177e4 | 54 | { |
0216bfcf | 55 | s64 ret = fbc->count; |
1da177e4 LT |
56 | |
57 | barrier(); /* Prevent reloads of fbc->count */ | |
0216bfcf | 58 | if (ret >= 0) |
1da177e4 LT |
59 | return ret; |
60 | return 1; | |
61 | } | |
62 | ||
63 | #else | |
64 | ||
65 | struct percpu_counter { | |
0216bfcf | 66 | s64 count; |
1da177e4 LT |
67 | }; |
68 | ||
0216bfcf | 69 | static inline void percpu_counter_init(struct percpu_counter *fbc, s64 amount) |
1da177e4 | 70 | { |
0216bfcf | 71 | fbc->count = amount; |
1da177e4 LT |
72 | } |
73 | ||
74 | static inline void percpu_counter_destroy(struct percpu_counter *fbc) | |
75 | { | |
76 | } | |
77 | ||
252e0ba6 PZ |
78 | #define __percpu_counter_add(fbc, amount, batch) \ |
79 | percpu_counter_add(fbc, amount) | |
80 | ||
1da177e4 | 81 | static inline void |
aa0dff2d | 82 | percpu_counter_add(struct percpu_counter *fbc, s32 amount) |
1da177e4 LT |
83 | { |
84 | preempt_disable(); | |
85 | fbc->count += amount; | |
86 | preempt_enable(); | |
87 | } | |
88 | ||
0216bfcf | 89 | static inline s64 percpu_counter_read(struct percpu_counter *fbc) |
1da177e4 LT |
90 | { |
91 | return fbc->count; | |
92 | } | |
93 | ||
0216bfcf | 94 | static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc) |
1da177e4 LT |
95 | { |
96 | return fbc->count; | |
97 | } | |
98 | ||
0216bfcf | 99 | static inline s64 percpu_counter_sum(struct percpu_counter *fbc) |
e2bab3d9 AM |
100 | { |
101 | return percpu_counter_read_positive(fbc); | |
102 | } | |
103 | ||
1da177e4 LT |
104 | #endif /* CONFIG_SMP */ |
105 | ||
106 | static inline void percpu_counter_inc(struct percpu_counter *fbc) | |
107 | { | |
aa0dff2d | 108 | percpu_counter_add(fbc, 1); |
1da177e4 LT |
109 | } |
110 | ||
111 | static inline void percpu_counter_dec(struct percpu_counter *fbc) | |
112 | { | |
aa0dff2d | 113 | percpu_counter_add(fbc, -1); |
1da177e4 LT |
114 | } |
115 | ||
3cb4f9fa PZ |
116 | static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount) |
117 | { | |
118 | percpu_counter_add(fbc, -amount); | |
119 | } | |
120 | ||
1da177e4 | 121 | #endif /* _LINUX_PERCPU_COUNTER_H */ |