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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> | |
11 | #include <linux/threads.h> | |
12 | #include <linux/percpu.h> | |
0216bfcf | 13 | #include <linux/types.h> |
1da177e4 LT |
14 | |
15 | #ifdef CONFIG_SMP | |
16 | ||
17 | struct percpu_counter { | |
18 | spinlock_t lock; | |
0216bfcf MC |
19 | s64 count; |
20 | s32 *counters; | |
1da177e4 LT |
21 | }; |
22 | ||
23 | #if NR_CPUS >= 16 | |
24 | #define FBC_BATCH (NR_CPUS*2) | |
25 | #else | |
26 | #define FBC_BATCH (NR_CPUS*4) | |
27 | #endif | |
28 | ||
0216bfcf | 29 | static inline void percpu_counter_init(struct percpu_counter *fbc, s64 amount) |
1da177e4 LT |
30 | { |
31 | spin_lock_init(&fbc->lock); | |
0216bfcf MC |
32 | fbc->count = amount; |
33 | fbc->counters = alloc_percpu(s32); | |
1da177e4 LT |
34 | } |
35 | ||
36 | static inline void percpu_counter_destroy(struct percpu_counter *fbc) | |
37 | { | |
38 | free_percpu(fbc->counters); | |
39 | } | |
40 | ||
0216bfcf MC |
41 | void percpu_counter_mod(struct percpu_counter *fbc, s32 amount); |
42 | s64 percpu_counter_sum(struct percpu_counter *fbc); | |
1da177e4 | 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 | ||
79 | static inline void | |
0216bfcf | 80 | percpu_counter_mod(struct percpu_counter *fbc, s32 amount) |
1da177e4 LT |
81 | { |
82 | preempt_disable(); | |
83 | fbc->count += amount; | |
84 | preempt_enable(); | |
85 | } | |
86 | ||
0216bfcf | 87 | static inline s64 percpu_counter_read(struct percpu_counter *fbc) |
1da177e4 LT |
88 | { |
89 | return fbc->count; | |
90 | } | |
91 | ||
0216bfcf | 92 | static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc) |
1da177e4 LT |
93 | { |
94 | return fbc->count; | |
95 | } | |
96 | ||
0216bfcf | 97 | static inline s64 percpu_counter_sum(struct percpu_counter *fbc) |
e2bab3d9 AM |
98 | { |
99 | return percpu_counter_read_positive(fbc); | |
100 | } | |
101 | ||
1da177e4 LT |
102 | #endif /* CONFIG_SMP */ |
103 | ||
104 | static inline void percpu_counter_inc(struct percpu_counter *fbc) | |
105 | { | |
106 | percpu_counter_mod(fbc, 1); | |
107 | } | |
108 | ||
109 | static inline void percpu_counter_dec(struct percpu_counter *fbc) | |
110 | { | |
111 | percpu_counter_mod(fbc, -1); | |
112 | } | |
113 | ||
114 | #endif /* _LINUX_PERCPU_COUNTER_H */ |