Commit | Line | Data |
---|---|---|
3cbc5640 RT |
1 | /* |
2 | * Fast batching percpu counters. | |
3 | */ | |
4 | ||
5 | #include <linux/percpu_counter.h> | |
c67ad917 AM |
6 | #include <linux/notifier.h> |
7 | #include <linux/mutex.h> | |
8 | #include <linux/init.h> | |
9 | #include <linux/cpu.h> | |
3cbc5640 RT |
10 | #include <linux/module.h> |
11 | ||
c67ad917 AM |
12 | #ifdef CONFIG_HOTPLUG_CPU |
13 | static LIST_HEAD(percpu_counters); | |
14 | static DEFINE_MUTEX(percpu_counters_lock); | |
15 | #endif | |
16 | ||
3a587f47 PZ |
17 | void percpu_counter_set(struct percpu_counter *fbc, s64 amount) |
18 | { | |
19 | int cpu; | |
20 | ||
21 | spin_lock(&fbc->lock); | |
22 | for_each_possible_cpu(cpu) { | |
23 | s32 *pcount = per_cpu_ptr(fbc->counters, cpu); | |
24 | *pcount = 0; | |
25 | } | |
26 | fbc->count = amount; | |
27 | spin_unlock(&fbc->lock); | |
28 | } | |
29 | EXPORT_SYMBOL(percpu_counter_set); | |
30 | ||
20e89767 | 31 | void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch) |
3cbc5640 | 32 | { |
20e89767 | 33 | s64 count; |
0216bfcf | 34 | s32 *pcount; |
3cbc5640 RT |
35 | int cpu = get_cpu(); |
36 | ||
37 | pcount = per_cpu_ptr(fbc->counters, cpu); | |
38 | count = *pcount + amount; | |
252e0ba6 | 39 | if (count >= batch || count <= -batch) { |
3cbc5640 RT |
40 | spin_lock(&fbc->lock); |
41 | fbc->count += count; | |
42 | *pcount = 0; | |
43 | spin_unlock(&fbc->lock); | |
44 | } else { | |
45 | *pcount = count; | |
46 | } | |
47 | put_cpu(); | |
48 | } | |
252e0ba6 | 49 | EXPORT_SYMBOL(__percpu_counter_add); |
3cbc5640 RT |
50 | |
51 | /* | |
52 | * Add up all the per-cpu counts, return the result. This is a more accurate | |
53 | * but much slower version of percpu_counter_read_positive() | |
54 | */ | |
bf1d89c8 | 55 | s64 __percpu_counter_sum(struct percpu_counter *fbc) |
3cbc5640 | 56 | { |
0216bfcf | 57 | s64 ret; |
3cbc5640 RT |
58 | int cpu; |
59 | ||
60 | spin_lock(&fbc->lock); | |
61 | ret = fbc->count; | |
b4ef0296 | 62 | for_each_online_cpu(cpu) { |
0216bfcf | 63 | s32 *pcount = per_cpu_ptr(fbc->counters, cpu); |
3cbc5640 RT |
64 | ret += *pcount; |
65 | } | |
66 | spin_unlock(&fbc->lock); | |
bf1d89c8 | 67 | return ret; |
3cbc5640 | 68 | } |
bf1d89c8 | 69 | EXPORT_SYMBOL(__percpu_counter_sum); |
c67ad917 | 70 | |
dc62a30e PZ |
71 | static struct lock_class_key percpu_counter_irqsafe; |
72 | ||
833f4077 | 73 | int percpu_counter_init(struct percpu_counter *fbc, s64 amount) |
c67ad917 AM |
74 | { |
75 | spin_lock_init(&fbc->lock); | |
76 | fbc->count = amount; | |
77 | fbc->counters = alloc_percpu(s32); | |
833f4077 PZ |
78 | if (!fbc->counters) |
79 | return -ENOMEM; | |
c67ad917 AM |
80 | #ifdef CONFIG_HOTPLUG_CPU |
81 | mutex_lock(&percpu_counters_lock); | |
82 | list_add(&fbc->list, &percpu_counters); | |
83 | mutex_unlock(&percpu_counters_lock); | |
84 | #endif | |
833f4077 | 85 | return 0; |
c67ad917 AM |
86 | } |
87 | EXPORT_SYMBOL(percpu_counter_init); | |
dc62a30e PZ |
88 | |
89 | int percpu_counter_init_irq(struct percpu_counter *fbc, s64 amount) | |
90 | { | |
91 | int err; | |
92 | ||
93 | err = percpu_counter_init(fbc, amount); | |
94 | if (!err) | |
95 | lockdep_set_class(&fbc->lock, &percpu_counter_irqsafe); | |
96 | return err; | |
97 | } | |
c67ad917 AM |
98 | |
99 | void percpu_counter_destroy(struct percpu_counter *fbc) | |
100 | { | |
833f4077 PZ |
101 | if (!fbc->counters) |
102 | return; | |
103 | ||
c67ad917 | 104 | free_percpu(fbc->counters); |
cf0ca9fe | 105 | fbc->counters = NULL; |
c67ad917 AM |
106 | #ifdef CONFIG_HOTPLUG_CPU |
107 | mutex_lock(&percpu_counters_lock); | |
108 | list_del(&fbc->list); | |
109 | mutex_unlock(&percpu_counters_lock); | |
110 | #endif | |
111 | } | |
112 | EXPORT_SYMBOL(percpu_counter_destroy); | |
113 | ||
114 | #ifdef CONFIG_HOTPLUG_CPU | |
115 | static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb, | |
116 | unsigned long action, void *hcpu) | |
117 | { | |
118 | unsigned int cpu; | |
119 | struct percpu_counter *fbc; | |
120 | ||
121 | if (action != CPU_DEAD) | |
122 | return NOTIFY_OK; | |
123 | ||
124 | cpu = (unsigned long)hcpu; | |
125 | mutex_lock(&percpu_counters_lock); | |
126 | list_for_each_entry(fbc, &percpu_counters, list) { | |
127 | s32 *pcount; | |
d2b20b11 | 128 | unsigned long flags; |
c67ad917 | 129 | |
d2b20b11 | 130 | spin_lock_irqsave(&fbc->lock, flags); |
c67ad917 AM |
131 | pcount = per_cpu_ptr(fbc->counters, cpu); |
132 | fbc->count += *pcount; | |
133 | *pcount = 0; | |
d2b20b11 | 134 | spin_unlock_irqrestore(&fbc->lock, flags); |
c67ad917 AM |
135 | } |
136 | mutex_unlock(&percpu_counters_lock); | |
137 | return NOTIFY_OK; | |
138 | } | |
139 | ||
140 | static int __init percpu_counter_startup(void) | |
141 | { | |
142 | hotcpu_notifier(percpu_counter_hotcpu_callback, 0); | |
143 | return 0; | |
144 | } | |
145 | module_init(percpu_counter_startup); | |
146 | #endif |