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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); | |
aa0dff2d | 35 | void percpu_counter_add(struct percpu_counter *fbc, s32 amount); |
0216bfcf | 36 | s64 percpu_counter_sum(struct percpu_counter *fbc); |
1da177e4 | 37 | |
0216bfcf | 38 | static inline s64 percpu_counter_read(struct percpu_counter *fbc) |
1da177e4 LT |
39 | { |
40 | return fbc->count; | |
41 | } | |
42 | ||
43 | /* | |
44 | * It is possible for the percpu_counter_read() to return a small negative | |
45 | * number for some counter which should never be negative. | |
0216bfcf | 46 | * |
1da177e4 | 47 | */ |
0216bfcf | 48 | static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc) |
1da177e4 | 49 | { |
0216bfcf | 50 | s64 ret = fbc->count; |
1da177e4 LT |
51 | |
52 | barrier(); /* Prevent reloads of fbc->count */ | |
0216bfcf | 53 | if (ret >= 0) |
1da177e4 LT |
54 | return ret; |
55 | return 1; | |
56 | } | |
57 | ||
58 | #else | |
59 | ||
60 | struct percpu_counter { | |
0216bfcf | 61 | s64 count; |
1da177e4 LT |
62 | }; |
63 | ||
0216bfcf | 64 | static inline void percpu_counter_init(struct percpu_counter *fbc, s64 amount) |
1da177e4 | 65 | { |
0216bfcf | 66 | fbc->count = amount; |
1da177e4 LT |
67 | } |
68 | ||
69 | static inline void percpu_counter_destroy(struct percpu_counter *fbc) | |
70 | { | |
71 | } | |
72 | ||
73 | static inline void | |
aa0dff2d | 74 | percpu_counter_add(struct percpu_counter *fbc, s32 amount) |
1da177e4 LT |
75 | { |
76 | preempt_disable(); | |
77 | fbc->count += amount; | |
78 | preempt_enable(); | |
79 | } | |
80 | ||
0216bfcf | 81 | static inline s64 percpu_counter_read(struct percpu_counter *fbc) |
1da177e4 LT |
82 | { |
83 | return fbc->count; | |
84 | } | |
85 | ||
0216bfcf | 86 | static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc) |
1da177e4 LT |
87 | { |
88 | return fbc->count; | |
89 | } | |
90 | ||
0216bfcf | 91 | static inline s64 percpu_counter_sum(struct percpu_counter *fbc) |
e2bab3d9 AM |
92 | { |
93 | return percpu_counter_read_positive(fbc); | |
94 | } | |
95 | ||
1da177e4 LT |
96 | #endif /* CONFIG_SMP */ |
97 | ||
98 | static inline void percpu_counter_inc(struct percpu_counter *fbc) | |
99 | { | |
aa0dff2d | 100 | percpu_counter_add(fbc, 1); |
1da177e4 LT |
101 | } |
102 | ||
103 | static inline void percpu_counter_dec(struct percpu_counter *fbc) | |
104 | { | |
aa0dff2d | 105 | percpu_counter_add(fbc, -1); |
1da177e4 LT |
106 | } |
107 | ||
108 | #endif /* _LINUX_PERCPU_COUNTER_H */ |