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Commit | Line | Data |
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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 | static LIST_HEAD(percpu_counters); |
13 | static DEFINE_MUTEX(percpu_counters_lock); | |
c67ad917 | 14 | |
3a587f47 PZ |
15 | void percpu_counter_set(struct percpu_counter *fbc, s64 amount) |
16 | { | |
17 | int cpu; | |
18 | ||
19 | spin_lock(&fbc->lock); | |
20 | for_each_possible_cpu(cpu) { | |
21 | s32 *pcount = per_cpu_ptr(fbc->counters, cpu); | |
22 | *pcount = 0; | |
23 | } | |
24 | fbc->count = amount; | |
25 | spin_unlock(&fbc->lock); | |
26 | } | |
27 | EXPORT_SYMBOL(percpu_counter_set); | |
28 | ||
20e89767 | 29 | void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch) |
3cbc5640 | 30 | { |
20e89767 | 31 | s64 count; |
0216bfcf | 32 | s32 *pcount; |
3cbc5640 RT |
33 | int cpu = get_cpu(); |
34 | ||
35 | pcount = per_cpu_ptr(fbc->counters, cpu); | |
36 | count = *pcount + amount; | |
252e0ba6 | 37 | if (count >= batch || count <= -batch) { |
3cbc5640 RT |
38 | spin_lock(&fbc->lock); |
39 | fbc->count += count; | |
40 | *pcount = 0; | |
41 | spin_unlock(&fbc->lock); | |
42 | } else { | |
43 | *pcount = count; | |
44 | } | |
45 | put_cpu(); | |
46 | } | |
252e0ba6 | 47 | EXPORT_SYMBOL(__percpu_counter_add); |
3cbc5640 RT |
48 | |
49 | /* | |
50 | * Add up all the per-cpu counts, return the result. This is a more accurate | |
51 | * but much slower version of percpu_counter_read_positive() | |
52 | */ | |
02d21168 | 53 | s64 __percpu_counter_sum(struct percpu_counter *fbc) |
3cbc5640 | 54 | { |
0216bfcf | 55 | s64 ret; |
3cbc5640 RT |
56 | int cpu; |
57 | ||
58 | spin_lock(&fbc->lock); | |
59 | ret = fbc->count; | |
b4ef0296 | 60 | for_each_online_cpu(cpu) { |
0216bfcf | 61 | s32 *pcount = per_cpu_ptr(fbc->counters, cpu); |
3cbc5640 RT |
62 | ret += *pcount; |
63 | } | |
64 | spin_unlock(&fbc->lock); | |
bf1d89c8 | 65 | return ret; |
3cbc5640 | 66 | } |
bf1d89c8 | 67 | EXPORT_SYMBOL(__percpu_counter_sum); |
c67ad917 | 68 | |
dc62a30e PZ |
69 | static struct lock_class_key percpu_counter_irqsafe; |
70 | ||
833f4077 | 71 | int percpu_counter_init(struct percpu_counter *fbc, s64 amount) |
c67ad917 AM |
72 | { |
73 | spin_lock_init(&fbc->lock); | |
74 | fbc->count = amount; | |
75 | fbc->counters = alloc_percpu(s32); | |
833f4077 PZ |
76 | if (!fbc->counters) |
77 | return -ENOMEM; | |
c67ad917 AM |
78 | #ifdef CONFIG_HOTPLUG_CPU |
79 | mutex_lock(&percpu_counters_lock); | |
80 | list_add(&fbc->list, &percpu_counters); | |
81 | mutex_unlock(&percpu_counters_lock); | |
82 | #endif | |
833f4077 | 83 | return 0; |
c67ad917 AM |
84 | } |
85 | EXPORT_SYMBOL(percpu_counter_init); | |
dc62a30e PZ |
86 | |
87 | int percpu_counter_init_irq(struct percpu_counter *fbc, s64 amount) | |
88 | { | |
89 | int err; | |
90 | ||
91 | err = percpu_counter_init(fbc, amount); | |
92 | if (!err) | |
93 | lockdep_set_class(&fbc->lock, &percpu_counter_irqsafe); | |
94 | return err; | |
95 | } | |
c67ad917 AM |
96 | |
97 | void percpu_counter_destroy(struct percpu_counter *fbc) | |
98 | { | |
833f4077 PZ |
99 | if (!fbc->counters) |
100 | return; | |
101 | ||
c67ad917 AM |
102 | #ifdef CONFIG_HOTPLUG_CPU |
103 | mutex_lock(&percpu_counters_lock); | |
104 | list_del(&fbc->list); | |
105 | mutex_unlock(&percpu_counters_lock); | |
106 | #endif | |
fd3d664f ED |
107 | free_percpu(fbc->counters); |
108 | fbc->counters = NULL; | |
c67ad917 AM |
109 | } |
110 | EXPORT_SYMBOL(percpu_counter_destroy); | |
111 | ||
179f7ebf ED |
112 | int percpu_counter_batch __read_mostly = 32; |
113 | EXPORT_SYMBOL(percpu_counter_batch); | |
114 | ||
115 | static void compute_batch_value(void) | |
116 | { | |
117 | int nr = num_online_cpus(); | |
118 | ||
119 | percpu_counter_batch = max(32, nr*2); | |
120 | } | |
121 | ||
c67ad917 AM |
122 | static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb, |
123 | unsigned long action, void *hcpu) | |
124 | { | |
179f7ebf | 125 | #ifdef CONFIG_HOTPLUG_CPU |
c67ad917 AM |
126 | unsigned int cpu; |
127 | struct percpu_counter *fbc; | |
128 | ||
179f7ebf | 129 | compute_batch_value(); |
c67ad917 AM |
130 | if (action != CPU_DEAD) |
131 | return NOTIFY_OK; | |
132 | ||
133 | cpu = (unsigned long)hcpu; | |
134 | mutex_lock(&percpu_counters_lock); | |
135 | list_for_each_entry(fbc, &percpu_counters, list) { | |
136 | s32 *pcount; | |
d2b20b11 | 137 | unsigned long flags; |
c67ad917 | 138 | |
d2b20b11 | 139 | spin_lock_irqsave(&fbc->lock, flags); |
c67ad917 AM |
140 | pcount = per_cpu_ptr(fbc->counters, cpu); |
141 | fbc->count += *pcount; | |
142 | *pcount = 0; | |
d2b20b11 | 143 | spin_unlock_irqrestore(&fbc->lock, flags); |
c67ad917 AM |
144 | } |
145 | mutex_unlock(&percpu_counters_lock); | |
179f7ebf | 146 | #endif |
c67ad917 AM |
147 | return NOTIFY_OK; |
148 | } | |
149 | ||
150 | static int __init percpu_counter_startup(void) | |
151 | { | |
179f7ebf | 152 | compute_batch_value(); |
c67ad917 AM |
153 | hotcpu_notifier(percpu_counter_hotcpu_callback, 0); |
154 | return 0; | |
155 | } | |
156 | module_init(percpu_counter_startup); |