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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); | |
3a587f47 | 35 | void percpu_counter_set(struct percpu_counter *fbc, s64 amount); |
20e89767 | 36 | void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch); |
52d9f3b4 | 37 | s64 percpu_counter_sum_positive(struct percpu_counter *fbc); |
1da177e4 | 38 | |
20e89767 | 39 | static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount) |
252e0ba6 PZ |
40 | { |
41 | __percpu_counter_add(fbc, amount, FBC_BATCH); | |
42 | } | |
43 | ||
0216bfcf | 44 | static inline s64 percpu_counter_read(struct percpu_counter *fbc) |
1da177e4 LT |
45 | { |
46 | return fbc->count; | |
47 | } | |
48 | ||
49 | /* | |
50 | * It is possible for the percpu_counter_read() to return a small negative | |
51 | * number for some counter which should never be negative. | |
0216bfcf | 52 | * |
1da177e4 | 53 | */ |
0216bfcf | 54 | static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc) |
1da177e4 | 55 | { |
0216bfcf | 56 | s64 ret = fbc->count; |
1da177e4 LT |
57 | |
58 | barrier(); /* Prevent reloads of fbc->count */ | |
0216bfcf | 59 | if (ret >= 0) |
1da177e4 LT |
60 | return ret; |
61 | return 1; | |
62 | } | |
63 | ||
64 | #else | |
65 | ||
66 | struct percpu_counter { | |
0216bfcf | 67 | s64 count; |
1da177e4 LT |
68 | }; |
69 | ||
0216bfcf | 70 | static inline void percpu_counter_init(struct percpu_counter *fbc, s64 amount) |
1da177e4 | 71 | { |
0216bfcf | 72 | fbc->count = amount; |
1da177e4 LT |
73 | } |
74 | ||
75 | static inline void percpu_counter_destroy(struct percpu_counter *fbc) | |
76 | { | |
77 | } | |
78 | ||
3a587f47 PZ |
79 | static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount) |
80 | { | |
81 | fbc->count = amount; | |
82 | } | |
83 | ||
252e0ba6 PZ |
84 | #define __percpu_counter_add(fbc, amount, batch) \ |
85 | percpu_counter_add(fbc, amount) | |
86 | ||
1da177e4 | 87 | static inline void |
20e89767 | 88 | percpu_counter_add(struct percpu_counter *fbc, s64 amount) |
1da177e4 LT |
89 | { |
90 | preempt_disable(); | |
91 | fbc->count += amount; | |
92 | preempt_enable(); | |
93 | } | |
94 | ||
0216bfcf | 95 | static inline s64 percpu_counter_read(struct percpu_counter *fbc) |
1da177e4 LT |
96 | { |
97 | return fbc->count; | |
98 | } | |
99 | ||
0216bfcf | 100 | static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc) |
1da177e4 LT |
101 | { |
102 | return fbc->count; | |
103 | } | |
104 | ||
52d9f3b4 | 105 | static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc) |
e2bab3d9 AM |
106 | { |
107 | return percpu_counter_read_positive(fbc); | |
108 | } | |
109 | ||
1da177e4 LT |
110 | #endif /* CONFIG_SMP */ |
111 | ||
112 | static inline void percpu_counter_inc(struct percpu_counter *fbc) | |
113 | { | |
aa0dff2d | 114 | percpu_counter_add(fbc, 1); |
1da177e4 LT |
115 | } |
116 | ||
117 | static inline void percpu_counter_dec(struct percpu_counter *fbc) | |
118 | { | |
aa0dff2d | 119 | percpu_counter_add(fbc, -1); |
1da177e4 LT |
120 | } |
121 | ||
3cb4f9fa PZ |
122 | static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount) |
123 | { | |
124 | percpu_counter_add(fbc, -amount); | |
125 | } | |
126 | ||
1da177e4 | 127 | #endif /* _LINUX_PERCPU_COUNTER_H */ |